Method and apparatus for facilitating continuous circulation of drilling mud during construction and maintenance of a well

0001The present invention relates to a method and an apparatus for facilitating continuous circulation of drilling mud during construction and maintenance of a well, preferably, but not exclusively for an oil or gas well. The present invention also relates to a system for continuous circulation wellbore operations.

0002In the construction of an oil or gas well, a borehole is drilled. A drill bit is arranged on the end of a drill string and is rotated to bore the borehole. A drilling fluid known as "drilling mud" is pumped through the drill string to the drill bit to lubricate the drill bit. The drilling mud is also used to carry the cuttings produced by the drill bit and other solids to the surface through an annulus formed between the drill string and the borehole and/or casing lining the borehole. The drill string is usually made up from a number of sections of threaded drill pipe.

0003In one prior art method of drilling a borehole with a drilling rig is to use a kelly bar having a square or other multisided cross-section, connected to a top joint of the drill string, which is used to rotate the drill string. A rotary table at the derrick floor level rotates the kelly bar while simultaneously the kelly bar can move vertically through a drive bushing within the rotary table at the rig floor. In another prior art method, a top drive drilling unit is suspended in a derrick grips and rotates the drill string and a kelly bar is not used. It is important to be able to control pressure in the borehole in relation to the pressure in the formation. In certain circumstances the driller may deem that under-balanced drilling is required, wherein the pressure exerted on a formation exposed in a wellbore is below the internal fluid pressure of that formation. Thus, if sufficient porosity and permeability exist, formation fluids enter the wellbore. The drilling rate typically increases as an under-balanced condition is approached. However, the driller may deem that over-balanced drilling is required, wherein the amount of pressure in the wellbore exceeds the pressure of fluids in the formation. This excess pressure is required inter alia to prevent reservoir fluids (oil, gas or water) from entering the wellbore. However, excessive overbalance can dramatically slow the drilling process by effectively strengthening the near-wellbore rock and limiting removal of drilled cuttings under the bit. In addition, high overbalance pressures coupled with poor drilling mud properties can cause differential sticking problems. Because reservoir pressures vary from one formation to another, while the drilling mud is relatively constant density, overbalance varies from one zone to another. The driller is able to vary the drilling condition from under-balanced to over-balanced by altering the density of the drilling mud by using weighting agents to increase or decrease the density of the drilling mud.

0004If the pressure in the well is not controlled properly, the speed of drilling is not maximised. In a worst case scenario, the well may collapse due to lack of pressure in the borehole. This is more likely to happen when drilling through particular types of formation.

0005In the past, circulation of drilling fluid is stopped during make-up or break-out of a single joint or stand of drill pipe. A fill valve or mud saver valve is used to contain pressure in the drill string during the make-up or break-out procedure. However, the valve has to be connected and disconnected each time. Thus there is discontinuous circulation, although pressure is substantially maintained in the well, a pulse of pressure change is noted. The circulation of drilling fluids can be extremely critical to maintaining a steady down hole pressure and a steady and near constant equivalent circulating density. Often when tripping a drill string into or out of a well, the lack of continuous circulation of a drilling fluid can cause pressure changes in the well which increase the probability of undesirable "kicks". The connection of sections of casing in a wellbore present similar problems with circulating fluids.

0006It is often preferable to maintain drilled cuttings in suspension in the drilling fluid to facilitate moving them away from the drill bit and to prevent them from falling back down in a wellbore. Cessation of drilling mud circulation can cause the drilled cuttings to sink. To counter this in many prior art systems additional fluid weighting is attempted, often increasing the viscosity of the fluid. This results in the need for more pumping power at the surface to move the thicker fluid; but such an increase in pump force can result in over pressuring the wellbore which can cause formation damage or loss of fluids.

0007A continuous circulation system has been developed and is disclosed in <patcit id="pcit0001" dnum="WO9816716A"><text>PCT Publication No. WO 98/16716</text></patcit>, which allows circulation of drilling mud to be carried out throughout the making-up and breaking-out of pipe to and from a pipe string. <patcit id="pcit0002" dnum="WO9816716A"><text>WO 98/16716</text></patcit> discloses, inter alia the use of an upper set of pipe rams to apply and seal about a single or stand of pipe to be connected to the string, a lower set of pipe rams to apply and seal about the pipe at the top of the string in the well to create a chamber therebetween and a blind ram to seal off the chamber between the end pin of the pipe to be connected and the box of the pipe at the top of the string to form upper and lower chambers. A drilling mud inlet is arranged in the lower chamber between the set of blind rams and the lower set of pipe rams. A drilling mud supply is also connected to the top end of the pipe to be connected, thus to make a connection, the lower pipe rams are activated and seal about the top end of the string of pipe in the wellbore and the blind rams are activated to form a lower chamber about the top of the drill string. Drilling mud is allowed to flow into the lower chamber and circulate into the top of the drill string. The drilling mud passes through the drill string to the drill bit and returns through an annulus formed by the drill string and the borehole. The drilling mud is processed by shale shakers, centrifuges and the like to remove cuttings therefrom, additives added if needed and then circulated to the lower chamber. Meanwhile, a single or stand of pipe is lowered into the top of the continuous circulation system. The upper pipe rams are activated to seal about the pipe. The upper end of the single or stand of pipe is attached to the supply of drilling mud and drilling mud flows into the upper chamber by activation of a valve. The pressures in the upper and lower chambers are now substantially equal. The blind ram is opened and the pin end of the single or stand of pipe is stabbed into the box in the top end of the string of pipe and spun and torqued to make the connection. The drilling mud in the chamber may be drained and the upper and lower pipe rams opened to allow the pipe string with the added single or stand of pipe to be lowered into the well. Thus a circulation is continuous through the pipe string and annulus whilst the connection is made and broken.

0008Various improvements to the continuous circulation system have been made, including conducting continuous circulation whilst drilling. This allows a continuous rotation of the drill string to allow drilling to continue whilst the single or stand of pipe is connected or disconnected from the string. This is useful for drilling with drill pipe or when drilling with casing.

0009<patcit id="pcit0003" dnum="WO2005019596A"><text>WO 2005/019596</text></patcit> discloses a continuous circulating system using a drill string sub having a wall defining a bore, the wall having a port therein and a valve for selectively opening and closing the port.

0010United States Published Patent Application Publication No. <patcit id="pcit0004" dnum="US20030221519A"><text>2003-0221519 published December 4, 2003</text></patcit> (<patcit id="pcit0005" dnum="USSN382080A" dnum-type="L"><text>USSN 382080, filed: March 5, 2003</text></patcit>) discloses an apparatus that permits sections of tubulars to be connected to or disconnected from a string of pipe during a drilling operation. The apparatus further permits the sections of drill pipe to be rotated and to be axially translated during the connection or disconnection process. The apparatus further allows for the continuous circulation of fluid to and through the tubular string during the makeup or breakout process. The apparatus defines a rig assembly comprising a top drive mechanism, a rotary drive mechanism, and a fluid circulating device. Rotation and axial movement of the tubular string is alternately provided by the top drive and the rotary drive. Additionally, continuous fluid flow into the tubular string is provided through the circulation device and alternately through the tubular section once a connection is made between an upper tubular connected to the top drive mechanism and the tubular string. This application also discloses a method for connecting an upper tubular to a top tubular of a tubular string while continuously drilling, the method including steps of: operating a rotary drive to provide rotational and axial movement of the tubular string in the wellbore; positioning the upper tubular above the top tubular of the tubular string, the upper tubular configured to have a bottom threaded end that connects to a top threaded end of the top tubular; changing a relative speed between the upper tubular and the top tubular to threadedly mate the bottom threaded end of the upper tubular and the top threaded end of the top tubular such that the upper tubular becomes a part of the tubular string; releasing the tubular string from engagement with the rotary drive; and operating a top drive to provide rotational and axial movement of the tubular string in the wellbore.

0011In some prior art systems in which a top drive is used for drilling, a stand of drill pipe (for example, a 27m (90 feet) stand comprising three interconnected pieces of drill pipe) is threadedly connected to and below a saver sub. The saver sub is connected to part of a top drive drilling unit and, once drilling has proceeded down to the extent of the length of a stand, the saver sub has entered into and is located within a chamber of a continuous fluid circulation system. In order to add a new stand with this type of prior art system, a connection is broken within a fluid circulating system, the top drive drilling unit is raised and, along with it, the saver sub is raised and exits from the top of the continuous circulation system. In order, then, to connect a new stand of drill pipe, a portion of a top drive drilling unit (for example, an elevator) is, in some prior art methods, moved away from the wellbore. Typically an elevator is associated with the top drive drilling unit, but this elevator often cannot be used to receive and support the new stand because a saver sub interferes with the operation.

0012In many cases, as a top drive drilling unit is raised, it is desirable to backream to circulate fluid and rotate the string coming out of the hole (the wellbore) as the top drive drilling unit is raised, for example, to smooth out the hole and prevent the formation of keyseats.

0013Another problem with such drilling systems is that it is desirable to drill down as far as possible with each new stand of drill pipe; but items and apparatuses (for example, elevators) suspended below a top drive drilling unit prevent further downward progress of the top drive drilling unit unless they are moved out of the way away from the wellbore centreline so that the top drive drilling unit can continue to rotate the drill string as the top drive drilling unit's saver sub enters the continuous circulation system (and the top drive approaches the continuous circulation system). Typically, the elevator is moved in one direction away from the wellbore centerline (and prior art elevators that only open to one side are used).

0014There are a variety of known continuous circulation systems; for example, and not by way of limitation, the following U.S. Patents and application present exemplary systems and components thereof: <patcit id="pcit0006" dnum="US7350587B"><text>7,350,587</text></patcit>; <patcit id="pcit0007" dnum="US7107875B"><text>7,107,875</text></patcit>; <patcit id="pcit0008" dnum="US6412554B"><text>6,412,554</text></patcit>; <patcit id="pcit0009" dnum="US6315051B"><text>6,315,051</text></patcit>; <patcit id="pcit0010" dnum="US6591916B"><text>6,591,916</text></patcit>; <patcit id="pcit0011" dnum="US3298385A"><text>3,298,385</text></patcit>; <patcit id="pcit0012" dnum="US1491986A"><text>1,491,986</text></patcit>; and <patcit id="pcit0013" dnum="US44966206A" dnum-type="L"><text>U.S. Application Serial No. 11/449,662 filed June 9, 2006</text></patcit>.

0015These are a variety of known wellbore, subs, continuous circulation systems, and related components, including, for example, the disclosures of <patcit id="pcit0014" dnum="US2102555A"><text>U.S. Patents: 2,102,555</text></patcit>; <patcit id="pcit0015" dnum="US2158356A"><text>2,158,356</text></patcit>; <patcit id="pcit0016" dnum="US4310050A"><text>4,310,050</text></patcit>; <patcit id="pcit0017" dnum="US4448267A"><text>4,448,267</text></patcit>; <patcit id="pcit0018" dnum="US4646844A"><text>4,646,844</text></patcit>; <patcit id="pcit0019" dnum="US6253861A"><text>6,253,861</text></patcit>; <patcit id="pcit0020" dnum="US6688394A"><text>6,688,394</text></patcit>; <patcit id="pcit0021" dnum="US6739397A"><text>6,739,397</text></patcit>; <patcit id="pcit0022" dnum="US7028787A"><text>7,028,787</text></patcit>; <patcit id="pcit0023" dnum="US7134489A"><text>7,134,489</text></patcit>; and <patcit id="pcit0024" dnum="US7281582A"><text>7,281,582</text></patcit>; and <patcit id="pcit0025" dnum="US20020157838A" dnum-type="L"><text>U.S. Applications Publication Nos. 2002/0157838 published Oct. 31, 2002</text></patcit>; and <patcit id="pcit0026" dnum="US20060254822A" dnum-type="L"><text>2006/0254822 published Nov. 16, 2006</text></patcit>.

0016Various prior systems have a variety of disadvantages and problems associated with their use; for example, in some prior systems valves internal to a sub are sent down a well where they are susceptible to wear and failure. Many items (for example, fishing tool, logging equipment, downhole tools, etc.) to be located in a wellbore beneath a sub are limited in diameter to a diameter which will pass through the sub. In certain aspects, a valve seat portion of a sub will have a relatively small diameter which limits the size of items which can be inserted through the sub.

0017"Iron roughnecks," combine a torque wrench and a spinning wrench to connect and disconnect tubulars, for example, drilling components, for example, drill pipe, in running a string of tubulars into or out of a well. Prior art iron roughnecks are shown for example,, in <patcit id="pcit0027" dnum="US4023449A"><text>U.S. Patents Nos. 4,023,449</text></patcit>; <patcit id="pcit0028" dnum="US4348920A"><text>4,348,920</text></patcit>; <patcit id="pcit0029" dnum="US4765401A"><text>4,765,401</text></patcit>; <patcit id="pcit0030" dnum="US6776070A"><text>6,776,070</text></patcit>; <patcit id="pcit0031" dnum="US7062991A"><text>7,062,991</text></patcit>; <patcit id="pcit0032" dnum="US7188547A"><text>7,188,547</text></patcit>; and <patcit id="pcit0033" dnum="US7313986A"><text>7,313,986</text></patcit>. Certain prior art iron roughnecks have a spinning wrench and a torque wrench mounted together on a carriage. For making or breaking threaded connections between two tubulars, for example, joints of drill pipe, certain iron roughnecks have a torque wrench with two jaw levels. An upper jaw of the torque wrench is used to clamp onto a portion of an upper tubular, and a lower jaw clamps onto a portion of a lower tubular, for example, upper and lower threadedly connected pieces of drill pipe. After clamping onto a tubular, the upper and lower jaws are turned relative to each other to break or make a connection between the upper and lower tubulars. A spinning wrench, mounted on the carriage above the torque wrench, engages the upper tubular and spins it until it is disconnected from the lower tubular (or in a connection operation, spins two tubulars together prior to final make-up by the torque wrench).

0018Certain iron roughnecks are mounted for movement from a wellbore center to a retracted position which does not interfere with or block performance of other operations relative to the well and rotating or driving apparatuses. Such a prior art system can be used for making and breaking joints in a main string or for connecting to or disconnecting from a tubular section located apart from a wellbore center, for example, in a mousehole (or rathole) at a side of a well.

0019Certain prior art iron roughneck systems include a carriage for rolling on the surface of the rig floor along a predetermined path. In certain prior art systems a spinner and torque wrench are mounted for upward and downward movement relative to a carriage, for proper engagement with tubulars, and for tilting movement between a position in which their axis extends directly vertically for engagement with a vertical well pipe and a position in which the axis of the spinner and torque wrench is disposed at a slight angle to true vertical to engage and act against a pipe in an inclined mousehole. In certain prior art systems, a spinner is movable vertically with respect to a torque wrench.

0020There are a variety of known torque wrenches and tongs for use in wellbore operations, for example,, but not limited to, as disclosed in and referred to in <patcit id="pcit0034" dnum="US3892140A"><text>U.S. Patents 3,892,140</text></patcit>; <patcit id="pcit0035" dnum="US4221269A"><text>4,221,269</text></patcit>; <patcit id="pcit0036" dnum="US4425827A"><text>4,425,827</text></patcit>; <patcit id="pcit0037" dnum="US4446761A"><text>4,446,761</text></patcit>; <patcit id="pcit0038" dnum="US6684737A"><text>6,684,737</text></patcit>; <patcit id="pcit0039" dnum="US6971283A"><text>6,971,283</text></patcit>; <patcit id="pcit0040" dnum="US5161438A"><text>5,161,438</text></patcit>; <patcit id="pcit0041" dnum="US5159860A"><text>5,159,860</text></patcit>; <patcit id="pcit0042" dnum="US5842390A"><text>5,842,390</text></patcit>; <patcit id="pcit0043" dnum="US5245877A"><text>5,245,877</text></patcit>; <patcit id="pcit0044" dnum="US5259275A"><text>5,259,275</text></patcit>; <patcit id="pcit0045" dnum="US5390568A"><text>5,390,568</text></patcit>; <patcit id="pcit0046" dnum="US4346629A"><text>4,346,629</text></patcit>; <patcit id="pcit0047" dnum="US5044232A"><text>5,044,232</text></patcit>; <patcit id="pcit0048" dnum="US5081888A"><text>5,081,888</text></patcit>; <patcit id="pcit0049" dnum="US5167173A"><text>5,167,173</text></patcit>; <patcit id="pcit0050" dnum="US5207128A"><text>5,207,128</text></patcit>; <patcit id="pcit0051" dnum="US5409280A"><text>5,409,280</text></patcit>; <patcit id="pcit0052" dnum="US5868045A"><text>5,868,045</text></patcit>; <patcit id="pcit0053" dnum="US6966385A"><text>6,966,385</text></patcit>; <patcit id="pcit0054" dnum="US6138529A"><text>6,138,529</text></patcit>; <patcit id="pcit0055" dnum="US4082017A"><text>4,082,017</text></patcit>; <patcit id="pcit0056" dnum="US6082224A"><text>6,082,224</text></patcit>; <patcit id="pcit0057" dnum="US6213216A"><text>6,213,216</text></patcit>; <patcit id="pcit0058" dnum="US6330911A"><text>6,330,911</text></patcit>; <patcit id="pcit0059" dnum="US6668684A"><text>6,668,684</text></patcit>; <patcit id="pcit0060" dnum="US6752044A"><text>6,752,044</text></patcit>; <patcit id="pcit0061" dnum="US6318214A"><text>6,318,214</text></patcit>; and <patcit id="pcit0062" dnum="US6142041A"><text>6,142,041</text></patcit>; <patcit id="pcit0063" dnum="US6253845A"><text>6,253,845</text></patcit>; and <patcit id="pcit0064" dnum="US7000502A"><text>7,000,502</text></patcit>.

0021In accordance with the present invention, there is provided a method for facilitating continuous circulation of drilling mud during construction and maintenance of a well, the method comprising the steps of moving a housing of a continuous circulation tool to a sub having a bore therethrough, the sub in or for connection in a string of tubulars in the well and selectively allowing drilling mud to flow between the housing and a side opening in the sub, the continuous circulation tool further comprising a closure apparatus, activating a closure mechanism to insert a closure member of the closure apparatus through the side opening in the sub to isolate of drilling fluid through at least a portion of the bore. Preferably, the closure mechanism applies the closure member at an angle to the direction of flow of drilling mud through the bore of the sub, the angle not being perpendicular and preferably between five and eighty-nine degrees and advantageously between forty five and eighty-nine degrees. Preferably, the closure member has a substantially planar face which prevents flow through the bore.

0022Preferably, the flow of drilling fluid into the well is directed from the housing by the closure member. Advantageously, the closure apparatus comprises a channel for channelling drilling fluid through the closure member and to or from the bore of the sub. Fluid in the bore above the closure member may be drained off through the channel and returned to an Active mud Recovery System (ARS) or to be processed before being sent back to the Active mud Recovery System to remove solids and other contaminates therefrom.

0023Preferably, the method further comprises the step of removing a plug from the side opening before inserting the closure member through the side opening. Advantageously, the step of removing the plug is carried out by inserting a stinger into the plug to facilitate removal of the plug. Preferably, the stinger is inserted between at least two members to move the at least two member apart to allow the plug to be removed from the side opening. Preferably, the sub further comprises two spaced-apart side opening recesses in communication with the side opening, and a securement mechanism including one or two dogs, the or each of the dogs selectively movable into and out of one of the two spaced-apart side opening recesses. Advantageously, the method further comprises the step of activating a plug movement device to remove and replace the plug. Preferably, the method further comprises the steps of removing the closure member from the bore through the side opening and replacing the plug. Preferably, the sub is a stand of tubular, such as drill pipe. Advantageously, once the plug is replaced, the sub is sent down the well in the string of tubulars. Advantageously, the closure mechanism comprises at least one selectively extendible member. Preferably, the closure mechanism comprises a powered extendible member. Advantageously, the powered extendible member is at least one of: a hydraulically actuated piston and cylinder; a pneumatically actuated piston and cylinder; a rack and pinion; and a linear actuator. Preferably, the extendible member has a first and second end and the powered extendible member has a proximal and distal end, the first end comprising the closure member, the second end movably attached to the distal end and the proximal end attached to the housing. Preferably, the proximal end of the powered extendible member is attached to the housing on a pin, wherein the extendible member is movable on the pin. Alternatively, a ball and socket joint may be used. Preferably, at least part of the extendible member is located inside the housing of the continuous circulation tool and part outside of the housing. Advantageously, the extendible member passes through the housing in a rotatable seal. Advantageously, the powered extendible member is located outside the housing.

0024Preferably, the sub comprises a shoulder, the method comprising the step of abutting the closure member against the shoulder. Preferably, a seal is formed between the closure member and shoulder. Advantageously, the bore has a region of an enlarged diameter in an area adjacent the side opening, the shoulder formed by a transition zone between the region and the bore.

0025Advantageously, the continuous circulation tool is arranged on an arm for facilitating movement of the continuous circulation tool to and from the sub. Preferably, the other end of the arm is fitted on a post connected to the drill floor.

0026Advantageously, a tubular manipulation apparatus is arranged above the continuous circulation tool, the method comprising the step of using the tubular manipulation apparatus to facilitate a connection of the sub with a tubular, preferably, a single or a stand of two, three or more tubulars. The tubulars may be drill pipe, tool pipe, casing, liner, premium tubular or any tool or downhole tool for connection with the string of tubulars. Preferably, the tubular manipulation apparatus is arranged on an arm. Preferably, the continuous circulation tool moves in concert with the tong apparatus. Advantageously, the tubular manipulation apparatus is at least one of: a power tong; back-up tong; pipe spinner; spinning wrench; and iron roughneck.

0027The present invention also provides an apparatus for carrying out the method of the invention, the apparatus comprising a sub for connection in a string of tubulars and a continuous circulation tool, the sub comprising a body having a bore therethrough, and a side opening, the continuous circulation tool comprising a housing in fluid communication with the side opening and a closure apparatus comprising a closure mechanism and a closure member selectively insertable into and removable from the side opening to selectively isolate flow of drilling fluid through at least a portion of the bore.

0028Advantageous and preferable features of the apparatus are set out in claim 12 to 15 for carrying out the method of the invention.

0029The sub permits continuous circulation of drilling fluid and the continuous circulation tool provides selective opening of a sub side opening and selective prevention of fluid flow from the top of the sub to and through the sub, while fluid is flowable from the side of the sub down into a tubular string below the sub; and any such system and method used with tubular manipulation apparatus, for example, but not limited to, a tong, tongs, a tong and back-up, a tong and a spinner, or an iron roughneck.

0030For a better understanding of the present invention, reference will now be made, by way of example, to the accompanying drawings, in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Figure 1A</figref> is a perspective view of an apparatus in accordance with the present invention comprising a sub and a continuous circulation tool;</li><li><figref idref="f0001">Figure 1B</figref> is a side cross-section view of the apparatus shown in <figref idref="f0001">Figure 1A</figref>;</li><li><figref idref="f0002">Figure 2A</figref> is a top view in cross-section of apparatus shown in <figref idref="f0001">Figure 1A</figref> in a first step of operation;</li><li><figref idref="f0002">Figure 2B</figref> is an enlarged view of part of the apparatus in the step shown in <figref idref="f0002">Figure 2A</figref>;</li><li><figref idref="f0003">Figure 3A</figref> is a top view in cross-section of the apparatus shown in <figref idref="f0001">Figure 1A</figref> in a second step of operation;</li><li><figref idref="f0003">Figure 3B</figref> is an enlarged view of part of the apparatus in the step shown in <figref idref="f0003">Figure 3A</figref>;</li><li><figref idref="f0004">Figure 3C</figref> is a view in cross-section of part of the sub shown in <figref idref="f0001">Figure 1A</figref>;</li><li><figref idref="f0004">Figure 3D</figref> is a view in cross-section of part of the sub shown in <figref idref="f0001">Figure 1A</figref>;</li><li><figref idref="f0005">Figure 4A</figref> is a top view in cross-section of the apparatus shown in <figref idref="f0001">Figure 1A</figref> in a third step of operation;</li><li><figref idref="f0005">Figure 4B</figref> is an enlarged view of part of the apparatus in the step shown in <figref idref="f0005">Figure 4A</figref>;</li><li><figref idref="f0006">Figure 5</figref> is a side view in cross-section of the apparatus shown in <figref idref="f0001">Figure 1A</figref> in a fourth step of operation;</li><li><figref idref="f0007">Figure 6</figref> is a side view in cross-section of the apparatus shown in <figref idref="f0001">Figure 1A</figref> in a fifth step of operation;</li><li><figref idref="f0007">Figure 7</figref> is a side view in cross-section of the apparatus as shown in <figref idref="f0001">Figure 1A</figref> in a fifth step of operation;</li><li><figref idref="f0008">Figure 8</figref> is a side view in cross-section of the apparatus shown in <figref idref="f0001">Figure 1A</figref> in a sixth step of operation;</li><li><figref idref="f0008">Figure 9</figref> is a side view in cross-section of the apparatus shown in <figref idref="f0001">Figure 1A</figref> in a seventh step of operation;</li><li><figref idref="f0009">Figure 10</figref> is an enlarged of part of the apparatus in the step shown in <figref idref="f0008">Figure 9</figref>;</li><li><figref idref="f0009">Figure 10A</figref> is a view in cross-section of the part shown in <figref idref="f0009">Figure 10</figref> with a seated closure member;</li><li><figref idref="f0010">Figure 11A</figref> is a side view illustrating an apparatus in accordance with the present invention, the apparatus comprising an iron roughneck;</li><li><figref idref="f0011">Figure 11B</figref> is a side view showing the apparatus shown in <figref idref="f0010">Figure 11A</figref> in an extended position;</li><li><figref idref="f0012">Figure 11C</figref> is a perspective view of the apparatus shown in <figref idref="f0011">Figure 11B</figref>;</li><li><figref idref="f0013">Figure 11D</figref> is a perspective view of the apparatus shown in <figref idref="f0011">Figure 11B</figref>, with the iron roughneck removed;</li><li><figref idref="f0014">Figure 12A</figref> is a top schematic view of an apparatus in accordance with the present invention in a non-extended "parked" position;</li><li><figref idref="f0014">Figure 12B</figref> is a top view showing a first step in a method of using the apparatus shown in <figref idref="f0014">Figure 12A</figref>;</li><li><figref idref="f0015">Figure 12C</figref> is a top view showing a second step in a method using the apparatus shown in <figref idref="f0014">Figure 12A</figref>;</li><li><figref idref="f0016">Figure 12D</figref> is a top view showing a third step in a method using the apparatus shown in <figref idref="f0014">Figure 12A</figref>;</li><li><figref idref="f0017">Figure 13A</figref> is a perspective view of part of the apparatus shown in <figref idref="f0014">Figure 12A</figref> in a first step of operation; and</li><li><figref idref="f0017">Figure 13B</figref> is a perspective view of part of the apparatus shown in <figref idref="f0014">Figure 12A</figref> in a second step of operation.</li></ul>

0031<figref idref="f0001">Figures 1A and 1B</figref> show an apparatus 1 for continuously circulating drilling mud in wellbore, the apparatus 1 comprising a sub 10 and a continuous circulation tool 100. The sub 10 has a body 12 with a flow bore 14 from top to bottom, a threaded pin end 16, and a threaded box end 18. The sub 10 is connected in a string TS of tubulars (parts TS1 and TS2 shown schematically, <figref idref="f0001">Figure 1B</figref>; for example, a string of drill pipe from a rig or platform extending down into the earth). The continuous circulation tool 100 has a housing 102.

0032A plug apparatus 20 is removably secured in an opening 13 of the body 12 of the sub 10. When secured in place, the plug apparatus 20 prevents fluid flow through the opening 13 (for example, see <figref idref="f0001">Figures 1B</figref>, <figref idref="f0002">2B</figref>, <figref idref="f0003">3B</figref>). A plug movement device 15 (shown schematically, <figref idref="f0001">Figures 1A, 1B</figref>) selectively activates and moves the plug apparatus 20. A control system 17 controls the plug apparatus 20 and a closure apparatus 40 (described below). The control system 17, in certain aspects, is directed to the type of controls used for the system; for example, and not by way of limitation, a control system can include: controls for a manual hydraulic valve system that operates the plug apparatus 20 and the closure apparatus 40; an electro-hydraulic control system; and a mechanical control system. In certain aspects the control system can employ linear motion devices (hydraulic, pneumatic, electric) which manipulate the closure apparatus 40 and plug apparatus 20 and other system components. The devices can be functional manually and/or via a computer system. Any such control system can have one or more computers, PLC's, and/or single board computers.

0033As shown in <figref idref="f0001">Figures 1B</figref> and <figref idref="f0002">2A</figref>, the plug movement device 15 moves a stinger structure 19 toward and away from the plug apparatus 20. The stinger structure 19 has a body 19a and a stinger 19b with a tip 19c.

0034The plug apparatus 20 has a plug 21 with a concave body portion 21a which has no part which projects into the bore 14 (it can be recessed from the inner bore surface of flush with it). Seals 22 (made, for example,, of rubber or of any suitable seal material) seal an opening 13 / plug-apparatus 20 interface. An anti-extrusion steel device 23 is on each side of the seals and helps to maintain the seals in place when pressure is applied to them. Fluid pressure pushing on the plug 21 pushes on the steel devices 23 which in turn push on the seals 22 to enhance sealing at the opening 13 / plug apparatus 20 interface. In one aspect, the outer surface of the plug 21 is flush with the inner surface of the bore (i.e., the curvature of the outer surface of the plug matches the curvature of inner surface of the bore).

0035Two spaced-apart locking dogs 24 are movable into and out of corresponding side opening recesses 13a. With the dogs 24 within the recesses 13a, the plug apparatus 20 is secured in place. Retracting the dogs 24 from the recesses 13a with a dog movement device 25 releases the plug apparatus 20 so it can be removed from the opening 13 (as in <figref idref="f0005">Figures 4A, 4B</figref>, <figref idref="f0006">5</figref>).

0036The plug 21 has an outer part 21o and a bore piece 21b with a bore 21r through which the stinger 19b can pass. Lock pins 21c hold the parts of the plug together.

0037The closure apparatus 40 has a closure structure 42 described in detail below.

0038As shown in <figref idref="f0005">Figures 4A and 4B</figref>, the stinger structure 19 has moved so that the stinger 19b with tip 19c has activated the dog movement device 25, retracting the dogs 24 from the recesses 13a. The stinger structure 19 is movable with respect to the plug apparatus 20. With the plug apparatus 20 freed from the body 12 of the continuous circulation sub 10, the plug movement device 15 can remove the plug apparatus 20 from the opening 13 as shown in <figref idref="f0006">Figure 5</figref>.

0039As shown in <figref idref="f0007">Figure 6</figref> the plug apparatus 20 is rotated away from the opening 13 by the plug movement device 15 and as shown in <figref idref="f0007">Figure 7</figref> the plug apparatus 20 has been rotated out of the way of the opening 13, for example, about ninety degrees from its position in <figref idref="f0006">Figure 5</figref>, and has been retracted so that a portion thereof is in a chamber 102a of the housing 102 of the continuous circulation system 100. Upon removal of the plug apparatus 20 from the opening 13 (for example, see <figref idref="f0006">Figure 5</figref>), fluid is flowable through the opening 13 into the bore 14 of the body 12 of the continuous circulation sub 10.

0040The opening 13 provides access to the bore 14 so that the closure structure 42 can be moved into position to close off flow through the bore 14. As shown in <figref idref="f0008">Figure 8</figref>, the closure apparatus 40 has been activated and has moved a shaft 41 (an extendable shaft, for example,, a telescoping shaft or other extendable shaft) toward the opening 13 so that the closure structure 42 is passing through the opening 13. A piston 43 of a piston/cylinder assembly 44 is retracted to effect this movement of the shaft 41. The shaft 41 moves in a bore 44a of a body 44. The bore 44a is in communication with the interior of the housing 102. The shaft 41 / body 44 interface is sealed with seals 45 and an end 44e of the body 44 is sealing secured in seal 45 in an opening 102b of the housing 102. An end 41e of the shaft 41 is secured to a pivot member 46 which is pivotably connected to an end 44g of the piston/cylinder assembly 44. Another end 44f of the piston/cylinder assembly 44 is pivotably connected to the housing 102. The closure structure 42 is mounted to or integrally formed with to the shaft 41 to rotate therewith. A rotation mechanism 49, shown schematically in <figref idref="f0001">Figure 1B</figref>, rotates the closure apparatus 42 by rotating the shaft 41 of the closure apparatus 42.

0041As shown in <figref idref="f0008">Figure 9</figref>, the closure apparatus 42 has been rotated and the piston and cylinder 44 retracted to slide the closure apparatus 42 along the inner wall of the bore 14t to seat against a shoulder 12s of the body 12 of the sub 10. During this step, the shaft 41 changes angle slightly, which is accommodated by the moveable seal 45.

0042It is within the scope of the present invention for the shaft 41 (and its parts or pieces) to be solid so that no fluid flow through the shaft 41 is possible. Optionally, the shaft 41 has a bore 41r therethrough from one end to the other; with a top end opening 41t and, via a port 46p in the pivot member 46 and a line 51, is in fluid communication with a reservoir system 50 or rig mud system (for example,, like the system ARS, <figref idref="f0001">Fig 1A</figref>). Valve apparatus 52 selectively controls flow in the line 51. Any suitable control system, including, but not limited to the control system 17, can control the valve apparatus 52. Any fluid, for example, drilling fluid, that enters the top of the continuous circulation sub 10 is vented to the reservoir 50.

0043Any suitable seal or seal structure may be used to seal the closure apparatus 42 against the shoulder 12s of the body 12 of the continuous circulation sub 10. Optionally, as shown in <figref idref="f0008">Figures 9</figref> and <figref idref="f0009">10</figref>, a pressure energized seal apparatus 54 may be used which includes a seal member 56 (made, for example, of rubber or of any suitable seal material) on top of which is a hard member 57 (for example, made of metal, steel, hard plastic, composite, etc.). Fluid pressure on the hard member 57 pressurizes and thereby energizes the seal member 56. The snap ring 59 maintains the member 57 and the seal member 57 in place. Optionally, as shown in <figref idref="f0009">Figure 10A</figref>, a closure member such as a plug, seal, or valve member 60 may be located to seal against a seal seat 62 of the body 12 of the sub 10 so that two barriers are provided within the body 12. The member 60 can be inserted from above or through the side opening.

0044For continuous circulation of fluid down a wellbore WB (<figref idref="f0001">Figure 1B</figref>, shown schematically), for example, when it is desired to add a new piece or stand of pipe above the sub 10, the plug 21 is removed from the opening 13 and then (with the plug 21 moved out of the way and the closure apparatus 42 positioned as shown in <figref idref="f0008">Figure 9</figref>) fluid is pumped from an active rig mud system ARS (<figref idref="f0001">Figure 1A</figref>; shown schematically) into the housing 102 of the system 100 via a channel 11a, through the opening 13 and downhole in the wellbore WB, thus providing continuous circulation.

0045[ It is within the scope of the present invention, among other things, to use an apparatus in accordance with the present invention (for example, like the apparatus 1) in combination with a sub in accordance with the present invention (for example, like the sub 10) with a tong ("tong" including tongs and spinners), with tongs, or with an iron roughneck. In one aspect a system in accordance with the present invention has an independent support and an independent movement apparatus for moving the system with respect to a tubular or a tubular string, and with respect to a tong, tongs, or an iron roughneck. In other aspects, a system in accordance with the present invention is supported from the same support or frame that supports a tong, tongs, or an iron roughneck and an extension apparatus connected to the support or frame moves the system in accordance with the present invention with the iron roughneck, or independently with respect thereto.

0046A system 200 in accordance with the present invention shown in <figref idref="f0010">Figures 11A</figref> and <figref idref="f0011">11B</figref> has, shown schematically, a manipulation apparatus 202 for manipulating tubulars (which may be any such apparatus, including, but not limited to, a tong, tongs, a tong and a back-up tong, a tong and a spinning wrench or spinner, or an iron roughneck) which, in one particular aspect, is an iron roughneck (any suitable known iron roughneck system or apparatus) with an extension apparatus 204 (shown schematically, <figref idref="f0011">Figure 11B</figref>) for extending and retracting the apparatus 202 with respect to a support frame 206.

0047A continuous circulation apparatus 100a in accordance with the present invention (like the continuous circulation apparatus 100 described herein, but not limited thereto) is connected to an extension apparatus 210 for extending and retracting the continuous circulation apparatus 100a with respect to the frame 206. Conduit apparatus 220 is in communication with the continuous circulation apparatus 100a and with an active rig mud system (for example, like the system ARS, <figref idref="f0001">Figure 1A</figref>).

0048A sub 10a (for example, like the sub 10 described above) is used with the system 200. The sub 10a is connected to a string SG extending down into a wellbore.

0049As shown in <figref idref="f0011">Figures 11B</figref> and <figref idref="f0012">11C</figref>, the iron roughneck 202 and the continuous circulation apparatus 100a have been moved toward and then adjacent the sub 10a. The continuous circulation apparatus 100a is operatively coupled to the iron roughneck 202 which is positioned to operate on a tubular above the sub 10a. The iron roughneck 202 can move with or independent of the continuous circulation apparatus 100a.

0050<figref idref="f0014 f0015 f0016">Figures 12A to 12D</figref> show various steps in the extension of a system 300 to move a continuous circulation apparatus 100b (like the continuous circulation apparatus 100a or the continuous circulation apparatus 100). An extension apparatus 230, connected to a support frame, box section or I-beam 228, has a back arm 232 pivotably connected at one end to the frame 228 and at the other end to a front arm 236. The front arm 236 is pivotably connected to the continuous circulation apparatus 100b. A conduit apparatus 250 connects the continuous circulation apparatus 100b to a mud system. The support frame 228, like the frame 206, can support the continuous circulation apparatus 100b and an iron roughneck, or tong(s) and spinner(s). The continuous circulation apparatus 100b may be moved by a separate movement system 100c (shown schematically, <figref idref="f0014">Figure 12A</figref>) or it can be selectively connected to an iron roughneck and move as the iron roughneck moves. With a latch 238 engaged, described below, the arm 232 cannot move and the arm 236 can move.

0051A latch 238, held in a latch engaged position with a latch member 238m on the frame 228 by the force of a spring 234, prevents the back arm 232 from moving when the continuous circulation apparatus 100b is in a "parked" position. The latch 238 has one end pivotably connected to the back arm 232 and another end pivotably connected to a linakge member 240 which is connected to the arm 236. The spring 234 is in the linkage member 240. Until the arm 236 is moved, while the latch 238 is engaged, the arm 232 is prevented from moving and the spring 234 urges an end rod 240a toward the latch 238.

0052As shown in <figref idref="f0015">Figure 12C</figref>, the latch has been disengaged and the continuous circulation apparatus 100b has begun its movement toward a well enter. Continued travel of the continuous circulation apparatus 100b is shown in <figref idref="f0015">Figure 12C</figref>.

0053<figref idref="f0016">Figure 12D</figref> shows the extension apparatus 230 fully extended and the continuous circulation apparatus 100b at well centre engaged with a sub 10b (like the sub 10a; like the sub 10).

0054Via a selective connection apparatus 100d shown schematically in <figref idref="f0014">Figure 12A</figref>), the continuous circulation apparatus 100b is selectively connected to an iron roughneck positioned above the system 100b (for example, like the iron roughneck 202, <figref idref="f0010">Figure 11A</figref>. Any suitable connection or connections can be used between the continuous circulation apparatus 100b and the iron roughneck, for example,/ but not limited to, a latch or latches; selectively projecting pins and/or pistons which project from one of the continuous circulation apparatus 100b and the iron roughneck to corresponding holes and/or recesses in the other; magnetic apparatuses; a roller or rollers on one of the items and selectively move into corresponding slots on the other item; and/or releasably cooperating fastener material.

0055<figref idref="f0017">Figures 13A and 13B</figref> illustrate operation of the latch 238. The spring 234 applies latching pressure to maintain the latch in a closed, engaged "parked" position (as in <figref idref="f0014">Figures 12A</figref> and <figref idref="f0017">13B</figref>). As shown in <figref idref="f0017">Figure 13A</figref> (and <figref idref="f0014">Figure 12B</figref>), with the latch disengaged, the arm 232 can move.

0056The conduit apparatus 250 extends and retracts with the system 100b. The conduit apparatus 250 includes sealed, pivotably connected conduits 252, 254 and flow line 256 in fluid communication with a mud system.

0057The present invention, therefore, provides in some, but not in necessarily all, embodiments a system for continuous circulation wellbore operations, the system including a sub system having a sub positionable in fluid communication with a wellbore tubular string, the sub having: a body, the body being generally cylindrical and having a first end, a second end, and an exterior surface, the second end connectible to a wellbore tubular string; a bore through the body from the first end to the second end, the bore having an inner boundary defined by an inner surface of the body, the bore positionable for fluid communication with the wellbore tubular string; a side opening in the body, the side opening extending from the exterior surface of the body to the inner surface; and the sub system further including closure apparatus including a housing in fluid communication with the side opening of the body of the sub, the closure apparatus including a closure mechanism outside the body, the closure mechanism including a closure member within the housing and selectively insertable into the side opening and removable from the bore of the body, the closure member movable to selectively close off flow from the first end of the body. Such a system may one or some, in any possible combination, of the following: tubular manipulation apparatus adjacent the sub system; wherein the tubular manipulation apparatus is one of tong, tongs, tong and back-up, tong and spinning wrench, and iron roughneck; wherein the sub system is selectively movable with the tubular manipulation apparatus; the sub further having a plug removably and sealingly secured in the side opening, the plug having a plug body, and a securement mechanism connected to the plug body for releasably securing the plug in the side opening; plug movement apparatus to which the plug is connected for moving the plug out of the side opening; the plug movement apparatus including stinger apparatus movable to connect with the plug and operate the securement mechanism to release the plug from the side opening; the sub further having two spaced-apart side opening recesses in communication with the side opening, and the securement mechanism including one or two dogs, the or each of the dogs selectively movable into and out of one of the two spaced-apart side opening recesses; wherein the inner surface of the body of the sub is curved and the plug has an outer curved surface, the outer surface of the plug substantially flush with the inner surface of the body; wherein the housing of the closure apparatus has an interior space and wherein fluid is flowable through the interior space of the housing into the bore of the body of the sub and out through the second end of the bore of the body so that continuous fluid circulation can be maintained in the wellbore tubular string; the closure apparatus including an extendable shaft, the extendable shaft extendable to position the closure member with respect to the bore of the body, the extendable shaft having a shaft channel therethrough, the closure member at an end of the extendable shaft, the closure member having a member channel therethrough, the member channel in fluid communication with the shaft channel so that with the closure member blocking fluid flow down to the second end of the sub fluid is flowable from the first end of the sub to and through the member channel of the closure member and then to and through the shaft channel; and/or wherein the fluid is drilling mud being pumped into the sub and flowing down through the first end of the body, and the shaft channel is in fluid communication with a rig mud system so that the drilling mud flowing out through the shaft channel flows to the rig mud system.

0058The present invention, therefore, provides in some, but not in necessarily all, embodiments a system for use in continuous circulation wellbore operations, the system including a sub system having a sub positionable in fluid communication with a wellbore tubular string, the sub having: a body, the body being generally cylindrical and having a first end, a second end, and an exterior surface, the second end connectible to a wellbore tubular string; a bore through the body from the first end to the second end, the bore having an inner boundary defined by an inner surface of the body, the bore positionable for fluid communication with the wellbore tubular string; a side opening in the body, the side opening extending from the exterior surface of the body to the inner surface; and the sub system further including closure apparatus including a housing in fluid communication with the side opening of the body of the sub, the closure apparatus including a closure mechanism outside the body, the closure mechanism including a closure member within the housing and selectively insertable into the side opening and removable from the bore of the body, the closure member movable to selectively close off flow from the first end of the body; plug apparatus having a plug body removably and sealingly secured in the side opening; a securement mechanism connected to the plug body for releasably securing the plug in the side opening; plug movement apparatus to which the plug is connected for moving the plug out of the side opening; the plug movement apparatus including stinger apparatus movable to connect with the plug and operate the securement mechanism to release the plug from the side opening; the housing of the closure apparatus having an interior space and wherein fluid is flowable through the interior space of the housing into the bore of the body of the sub and out through the second end of the bore of the body so that continuous fluid circulation can be maintained in the wellbore tubular string; the closure apparatus including an extendable shaft, the extendable shaft extendable to position the closure member with respect to the bore of the body, the extendable shaft having a shaft channel therethrough; the closure member at an end of the extendable shaft, the closure member having a member channel therethrough, the member channel in fluid communication with the shaft channel so that with the closure member blocking fluid flow down to the second end of the sub fluid is flowable from the first end of the sub to and through the member channel of the closure member and then to and through the shaft channel; wherein the fluid is drilling mud being pumped into the sub and flowing down through the first end of the body; the shaft channel is in fluid communication with a rig mud system so that the drilling mud flowing out through the shaft channel flows to the rig mud system; and tubular manipulation apparatus adjacent the sub system. In such a system, the tubular manipulation apparatus may be one of tong, tongs, tong and back-up, tong and spinning wrench, and iron roughneck.

0059The present invention, therefore, provides in some, but not in necessarily all, embodiments a system for continuous circulation wellbore operations, the system having: a sub system positionable in fluid communication with a wellbore tubular string; the sub system for selectively closing off flow to the wellbore tubular string; tubular manipulation apparatus adjacent the sub; and the tubular manipulation apparatus having one of tong, tongs, tong and back-up, tong and spinning wrench, and iron roughneck.