Method for measuring stratigraphic in situ static temperature

Method of measuring the static temperature of the formation site

Technical field

The invention relates to measuring the static temperature of the formation site in the well during the drilling phase. Stopping the circulation also means shutting in the well. The circulation is stopped to fill the wellbore with drilling mud, and the temperature of the drilling mud is usually different from the temperature of the undisturbed formation.

Background technique

One way to measure this temperature is to place a thermometer into the borehole filled with drilling mud and record the temperature at a predetermined depth as a function of the time (Δt) after the cycle is stopped. The thermometer can be a self-equipped temperature recorder or a surface recording thermometer. When the temperature does not change with time, the constant temperature can be considered as the static temperature of the formation site. However, the above method is time-consuming.

The following is an improved method of the above method. In this method, the temperature is plotted against log((tk+Δt)/Δt), where tk is the cycle time and Δt is the time after the cycle is stopped. The result of log((tk+Δt)/Δt) obtained by extrapolation is basically equal to zero, which means that the cycle time can be ignored relative to the time after the cycle is stopped. The temperature obtained by the extrapolation method can be regarded as the static temperature of the formation site.

However, if the cycle time is mistaken, it will have a great influence on the extrapolated temperature. And this kind of error is very easy to produce. For example, after the drilling phase is completed, the driller drags the drill bit upwards for hundreds of meters, and before shutting in, in order to clean the drill bit, the cycle lasts for several hours. In this case, the driller will report the sum of the cycle time required for drilling at a specific stage and the time required to clean the drill bit as the cycle time. But in order to obtain the temperature record, the cycle time should be the cycle time required for drilling at a specific stage.

Summary of the invention

An object of the present invention is to provide a more accurate method for measuring the static temperature on site.

To this end, the present invention provides a method for measuring the static temperature of the formation penetrated by the wellbore. The measurement method includes the following steps: a) A tool is lowered to a predetermined position in the well, and the tool includes a A central conduit with an inlet and a temperature sensor in contact with the fluid, a fluid analysis device, and a device for discharging fluid; b) forming a closed fluid communication between the formation and the inlet of the central conduit; c) making the formation fluid Through the central conduit; d) analyze the formation fluid; and e) continuously measure the temperature until the formation fluid is an uncontaminated fluid, and determine the on-site static temperature of the formation as the temperature of the uncontaminated formation fluid.

The present invention will be described in more detail below. The present invention provides a measurement method for measuring the field static temperature of the formation penetrated by a wellbore. The first step of the method is to lower a tool to a predetermined position in the wellbore. The tool includes a The central conduit of the temperature sensor in contact with the fluid, the fluid analysis device, and the fluid discharge device. The predetermined position may be the bottom of the wellbore, or a position in the formation where the static temperature of the formation on-site is to be measured. The tool is lowered into the borehole by, for example, a wire rope.

Then, an exclusive fluid communication is formed between the formation and the central conduit inlet. In order to form a closed fluid communication, a probe is extended into the formation, wherein the outlet of the probe is directly in fluid communication with the inlet of the central conduit of the tool. Since the inlet of the detector is located in the formation, the drilling mud in the wellbore cannot enter the central conduit, thus forming a closed fluid communication between the formation and the central conduit inlet, while the wellbore fluid is isolated.

The formation fluid is then passed through the central conduit. This process is completed by means of a suction pump, which sucks the formation fluid into the central duct through the detector, and discharges the formation fluid from the central duct. It can be understood that during the drilling of the hole, the drilling mud will invade the formation. Therefore, when the formation fluid is pumped out, the drilling mud will be pumped out first, then the mixture of the drilling mud and the original formation fluid will be pumped out, and finally the uncontaminated formation fluid will be pumped out.

When the formation fluid passes through the central conduit, it is analyzed to determine its composition.

The temperature of the formation fluid is then continuously measured until the formation fluid is essentially uncontaminated fluid. The applicant found that the temperature of the uncontaminated formation fluid is not simply the temperature of the fluid, but is indeed the static temperature of the site.

In the actual measurement process, both temperature and composition are recorded, and the on-site static temperature of the formation is the temperature of the formation fluid that is basically uncontaminated.

Since the temperature of the uncontaminated formation fluid is measured in the method of the present invention, this method is more accurate than the known method.

In addition, the method of the present invention can be implemented by a tool for collecting formation fluid samples, such as Schlumberger's Modular Dynamic Formation Tester (Modular Dynamic Formation Tester) tool. The tool also includes an accurate thermometer for calibrating the pressure sensor, and the output signal of the accurate thermometer can be used in the method of the present invention. Other suitable tools known in the art that can be used include Halliburton's repetitive dynamic tester and Western Atlas's reservoir characterization instrument (reservoir characterization instrument).

If the hydrocarbon reservoir fluid is a so-called heavy oil with a higher viscosity, it will be difficult to obtain a representative reservoir fluid sample. In order to obtain a representative sample, the step of forming a closed fluid communication further includes activating a heating device disposed near the probe to heat the formation.

As a suitable embodiment, the detector is connected to the packer pad in the assembly, and the heating device is arranged in the packer pad. As an optional embodiment, the heating device is provided on the tool. The heating device can be a device that generates microwaves, light waves or infrared waves. The heating device can also be an electric heater, a chemical heater or a nuclear heater.

The method of the present invention is also applicable to wells with casing. In this case, the step of lowering the tool into the borehole includes two steps. Firstly, a perforation group that penetrates the casing wall and enters the formation is formed at a position where the temperature needs to be determined, wherein the perforation group includes at least one perforation that extends into the formation. Then lower the tool into the cased hole. The tool also includes an upper packer and a lower packer arranged on both sides of the inlet of the central conduit, wherein the central conduit opens below the lower packer or above the upper packer, and the upper and lower packers The distance between them is greater than the height of a perforation group.

The step of establishing closed fluid communication involves setting up packers so that the perforation group spans between the packers.