Method of gravel packing well treatment

April 4, 1961 d. r. davis 2,978,024

METHOD OF GRAVEL PACKING WELL TREATMENT Filed Dec. 12, 1957

<img file="US2978024A_D0001.tif" />

United States Patent Office

2,978,024

Patented Apr. 4, 1961

A' &lt; ·: '· 1' A\

2,978,024

METHOD OF GRAVEL PACKING WELL TREATMENT

Douglass R. Davis, Houston, Tex., assignor to Texaco Inc., a corporation of Delaware

Filed Dec. 12, 1957, Ser. No. 702,356

Claims. (Cl. 166—15)

This invention relates to a method for the treatment of wells. In accordance with one embodiment this invention relates to the gravel packing of wells. In accordance with another embodiment this invention relates to an operation, wherein a well is gravel packed and, if desired, fractured in substantially the same operation.

In the production of petroleum from a petroleum producing formation one difficulty sometimes encountered, particularly when the petroleum producing formation is an unconsolidated formation, that the productivity of the well becomes reduced after a period of time due to the “sanding up” or plugging of the well. To avoid this reduction in well productivity due to the well “sanding up” it has been proposed heretofore to gravel pack a well. In a gravel packing operation a filter bed of porous granular material is deposited within the well bore adjacent the petroleum producing formation. This porous gravel bed serves to support the adjacent petroleum producing formation and tends to prevent the well from “standing up” due to the transport of finely divided solid material from the producing formation into the well bore.

Recently it has been proposed, see patent application Serial No. 401,159 filed December 30, 1953, now issued as Patent No. 2,814,347, the disclosure of which is herein incorporated and made part of this disclosure, to carry out a gravel packing operation and formation fracturing operation substantially simultaneously. The operations disclosed therein, however, are complicated and require the use of a rather large amount of equipment and production tubing or conduit.

It is, therefore, an object of this invention to provide an improved method of well treatment.

It is another object of this invention to provide an improved method of effecting gravel packing and formation fracturing substantially simultaneously.

Another object of this invention is to provide an improved method of gravel packing a well.

Still another object of this invention is to provide an improved method and apparatus suitable for use in pressure gravel packing a well.

Yet another object of this invention is to provide an improved well completion assembly or apparatus.

How these and other objects of this invention are accomplished will become apparent in the light of the accompanying disclosure made with reference to the accompanying drawings which schematically illustrate an embodiment of the practice of this invention particularly useful for carrying out a combination well gravel packing and fracturing operation and wherein Fig. 1 schematically illustrates the operation and asembly of apparatus in the initial stages of an operation in accordance with this invention and wherein Fig. 2 schematically illustrates a completed gravel packing-formation fracturing operation carried out in accordance with this invention.

In at least one embodiment of the practice of this invention at least one of the foregoing objects is accomplished.

In accordance with this invention it has now been discovered that an improved well completion operation is 5 obtained by disposing a well screen or liner within a well bore adjacent a petroleum producing formation and then carrying out a subsequent gravel packing operation in such a manner that the material (carrier liquid and granular material) employed in the gravel packing operation 10 is introduced into the well bore into contact with the petroleum producing formation undergoing treatment via the production tubing. The production tubing after completion of the well treatment or gravel packing operation is then employed to carry the produced petroleum 15 from the resulting treated formation.

Referring now to the accompanying drawings and to Fig. 1 which schematically illustrates an operation in accordance with this invention involving gravel packing in combination with formation fracturing there is shown 20 a well bore 11 provided with casing 12. As illustrated in Fig. 1, the casing 12 terminates within well bore 11 above the petroleum producing formation 14. Provided within casing 12 is production tubing 15. Removably attached to the bottom end of tubing 15 is well screen 25 or liner 16 which is disposed within well bore 11 adjacent the petroleum producing formation 14. Well screen 16 is releasably attached to the lower end of tubing 15 which is provided with back pressure foot valve 17 schematically illustrated in Fig. 1. A packer 18 posi30 tioned around the upper end of well screen 16 provides a fluid-tight seal between well screen 16 and casing 12. Further, a packer 19, such as a ring type packer, is provided in the annular space between the interior of the upper end of well screen 16 and tubing 15 and provides 35 a fluid-tight seal therebetween. Also, in fluid communication with the upper end of tubing 15 is production conduit 20.

Referring now in detail to Fig. 2 of the drawing wherein the same reference numerals employed with re40 spect to Fig. 1 have been employed to designate the same elements, there is schematically illustrated the petroleum producing formation 14 after having been treated in accordance with the practice of this invention. More particularly, Fig. 2 schematically illustrates that ⁴³ petroleum producing formation 14 has been fractured to produce a fracture 21 extending radially outwardly from the well bore 11. The fracture 21 is shown as having been filled with a mass of porous gravel 22. This mass of porous gravel material also occupies that ³⁰ portion of the well bore surrounding the outside of well screen 16. As illustrated, well packer 18 is positioned to provide a fluid-tight seal between the outside of well screen 16 and casing 12. Well screen ring type packer 19, however, although in substantially the same position ³³ as illustrated in Fig. 2 now provides a fluid-tight seal between the inside of the upper end of well screen 16 and the outside of the lower end of tubing 15. Further, as illustrated in Fig. 2 the one way check valve or back pressure foot valve 17 at the bottom of the well screen ³³ is closed.

In an operation in accordance with the practice of this invention wherein a petroleum producing formation is gravel packed a mixture of carrier liquid and granular material, such as sand or finely divided gravel, is intro⁶⁵ duced via production conduit 20 into tubing 15. This mixture is discharged from tubing 15 via back pressure foot valve 17 located at the bottom of well screen 16. A sufficient amount of liquid, together with granular material, is introduced to fill the annular space between well 70 screen 16 and the well bore 11. The carrier liquid will fill the interior of well screen 16 since well screen 16 is slotted or perforated and therefore is in direct fluid com

2,978,024 munication with the surrounding annular space. The granular material, however, remains outside well screen 16 within the annular space since this material is too large to pass through the^- slots or perforations of well screen 16. Further, since packer 18 and well screen ring type packer 19 are closed back flow of the mixture of carrier liquid and granular material upwardly into casing 12 is prevented. Pressure, by suitable means such as a pump (not shown), such as fluid pressure exerted by liquid filling tubing 15, is then exerted upon the liquid filling the interior of well screen 16 and the surrounding annular space. The exerted pressure is sufficient to force at least a portion of the mixture of carrier liquid and granular material within the annular space surrounding well screen 16 into the petroleum producing formation 14.

Desirably the pressure exerted upon the mixture within the annular space surrounding well screen 16 is sufficient to fracture the petroleum producing formation 14. When a fracture occurs, as illustrated in Fig. 2, at least a portion of the mixture of carrier liquid and granular material is forced into the formation, the granular material occupying fracture 21. Sufficient pressure may be exerted upon the mixture within the annular space surrounding well screen 16 to enlarge the resulting fracture 21 to any desired extent.

Since the interior of well screen 16 and the annular space within the well bore surrounding well screen 16 are in direct fluid communication substantially the same fluid pressure would exist within the well screen interior and the surrounding annular space. Further, with packers 18 and 19 positioned as illustrated in Figs. 1 and 2 the fluid pressure exerted upon the liquid within the well bore surrounding well screen 16 is readily maintained and exerted substantially exclusively against the producing formation 14 undergoing treatment.

When the petroleum producing formation 14 has been gravel packed, and desirably fractured, such that there remains a fracture 21 within the petroleum producing formation with gravel 22 deposited therein, as well as a residue or bed of granular material within the annular space defined between well screen 16 and the adjacent petroleum producing formation 14 as illustrated in Fig. 2, the pressure exerted upon the mixture within the annular space surrounding well screen 16 is released. Tubing 15 is released from the bottom of well screen 16 as by turning tubing 15 at the same time closing the back pressure foot valve 17. Also, the well screen ring type packer 19 is released and the tubing 15 lifted to the desired position illustrated in Fig. 2 and then packer 19 again set to provide a fluid -tight seal between the inside of well screen 16 and the lower end of tubing 15. Following the aforesaid operations the well is swabbed and petroleum production resumed from the resulting treated petroleum producing formation 14 via fracture 21, the mass of gravel 22 therein, well screen 16, tubing 15 and production conduit 20.

Although the drawings show the well bore 11 penetrating the petroleum producing formation 14 to be an open hole it is pointed out that the practice of this invention is applicable to a cased formation wherein the petroleum producing formation is provided with a perforated casing and the like. When the petroleum producing formation is provided with a perforated casing the mixture of granular material and carrier liquid is forced into the petroleum producing formation via the perforations in the casing and the fluid pressure exerted through these perforations is sufficient to fracture said formation.

Various fluids may be utilized as the carrier liquid employed in the gravel packing operations in accordance with the practices of this invention. These fluids include the normally liquid hydrocarbons, crude petroleum, lease crude, petroleum fractions, crude oil or kerosene, lease crude or petroleum fractions such as diesel oil or kerosene thickened with a suitable thickening or gelling agent such as sodium palmitate (Napalm) and the like. Aqueous liquids, such as water, thickened or unthickened with additives which increase the viscosity thereof and reduce fluid loss, as well as brines, such as formation brines, might be suitably employed as a carrier liquid in a gravel packing operation described herein.

As will be apparent to those skilled in the art many modifications, changes and alterations are possible in the practice of this invention without departing from the 1 spirit or scope thereof. j