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Method for determining formation fracture pressure gradient logging of shale gas reservoir

A technology for formation fracture pressure and determination method, which is applied in earthwork drilling, wellbore/well components, etc., can solve problems such as high risk, high cost of fracturing, difficulty in adapting to shale gas production needs, etc.

Active Publication Date: 2014-07-09
CHINA PETROCHEMICAL CORP +2
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Problems solved by technology

[0004] With the discovery of domestic shale gas fields and the expansion of shale gas exploration and development test scale, the cost and risk of multi-stage fracturing of shale gas horizontal wells are high, and the calculation accuracy of formation fracture pressure gradient and formation fracture pressure of shale gas reservoirs The requirements are getting higher and higher, and the traditional calculation method of formation fracture pressure gradient is difficult to meet the production needs of unconventional oil and gas layers such as shale gas, and the problem of large calculation errors is becoming more and more prominent

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  • Method for determining formation fracture pressure gradient logging of shale gas reservoir

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example 1

[0038] Example 1: Well J in a gas field

[0039] In the first step, choose to calculate according to the value of the layer. The 612.0-648.0m shale gas layer in Well J is calculated as the average value of one layer, and the vertical depth H in the middle of the gas layer is 630m;

[0040] The second step is to obtain the formation pressure gradient, and read the formation pressure gradient result data of the comprehensive mud logging formation pressure detection. The average value of the formation pressure gradient FPG is 1.07MPa / 100m;

[0041] The third step is to obtain the Poisson's ratio of the rock, the lithology density and gas saturation of the overlying strata, and read the data table of the processing results of the logging rock mechanics parameters. The average Poisson's ratio POIS is 0.30; The average density is 2.65g / cm 3 ; Read the log interpretation result data table, the average value of gas saturation Sg is 0.55;

[0042] The fourth step is to calculate the ...

example 2

[0047] Example 2: Well JY8-2 in a shale gas field

[0048] Well JY8-2 is a horizontal well with a long horizontal section, the vertical depth of the gas reservoir is 2340.0-2420.0m, and the horizontal section passes through the gas reservoir.

[0049] In the first step, the calculation is based on the value of the interval. The 2443.0-4150.0m shale gas layer in Well JY8-2 is calculated based on the average value of one interval. Vertical depth 2340.0m;

[0050] The second step is to obtain the formation pressure gradient, and read the formation pressure gradient result data of the comprehensive mud logging formation pressure detection. The average value of the formation pore fluid pressure gradient FPG is 1.45MPa / 100m;

[0051] The third step is to obtain the Poisson's ratio of the rock, the lithology density of the overlying formation and the gas saturation, and read the data table of the processing results of the logging rock mechanics parameters. The average Poisson's rati...

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Abstract

The invention relates to a method for determining formation fracture pressure gradient logging of a shale gas reservoir. The method comprises the following steps of calculating formation fracture pressure gradient of an objective layer of the shale gas reservoir by evaluating according to layers or according to certain step length in the layers; acquiring formation hole fluid pressure gradient of the objective layer through logging or well measuring information; acquiring the rock poisson ratio of the objective layer through logging or indoor core experimental analysis information; acquiring gas saturation through logging or well measuring information; acquiring overlaying formation lithology density through well measuring information; calculating the formation fracture pressure gradient FRAC of the shale gas reservoir according to the formula: FRAC=FPG+POIS / (1-POIS)*(DENb-Sg*FPG); and outputting a result according to a formula: FP=FRAC*H / 100. The method is applied to 32 shale gas wells in the Jiannan gas field of the middle yangtze region, the shale gas field of the Fuling region, the western Hunan region and the western Hubei region; and the error of a calculated value and the actually acquired formation fracture pressure gradient is &1t;10%.

Description

technical field [0001] The invention relates to a method for calculating and determining the rupture pressure gradient of a shale reservoir formation. Background technique [0002] Shale gas is a new type of clean energy and an important unconventional natural gas resource. The development of shale gas requires the drilling of horizontal wells in the "well factory" mode, and the shale gas reservoirs in the horizontal section of horizontal wells need to undergo multi-stage large-scale fracturing, which is costly and risky. The accuracy of calculation or prediction of formation fracture gradient and formation fracture pressure parameters in shale gas reservoirs is very important, which directly affects the effect of reservoir stimulation. [0003] The traditional calculation methods of formation fracture pressure gradient mainly include Eaton method, Matthews and Kelly method, and Christman method. These methods were mainly formed during the 1960s and 1970s to solve the prob...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B49/00
Inventor 张建平冯爱国石元会赵红燕肖世匡任元石文睿李光华田芳
Owner CHINA PETROCHEMICAL CORP
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