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A Calculation Method of Formation Fracture Pressure Gradient in Shale Gas Reservoir

A technology for formation fracture pressure and gradient calculation, which is applied in earth-moving drilling, wellbore/well components, measurement, etc., and can solve problems such as difficulty in adapting to production needs, large calculation errors, and high risks.

Active Publication Date: 2020-08-07
中石化石油工程技术服务有限公司 +1
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  • Application Information

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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, the traditional calculation method of formation fracture pressure gradient is difficult to meet the production needs, and the problem of large calculation errors is becoming more and more prominent

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  • A Calculation Method of Formation Fracture Pressure Gradient in Shale Gas Reservoir

Examples

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example 1

[0046] Example 1: Well JY2-3 in a certain gas field

[0047] 1) Collect the conventional logging curve data (including acoustic wave, density, and neutron curve) of the whole well section of the well, and use the weighted average method to calculate the average rock skeleton density ρma of 2.67g / cm2 using the density logging curve data 3 , the average porosity Φ of the formation is determined to be 0.05, and the fluid density ρw is 1.05g / cm by using the conventional logging curve data of the whole well section and the core porosity analysis data of the core well of the regional exploration well 3 ;

[0048] 2) Determine the well section of the shale gas reservoir to be 2980.0-4490.0m and the vertical depth to be 2448.0-2521.0m, and collect the data of acoustic wave, density and neutron logging curves of the shale reservoir section;

[0049] 3) By ρ=(1-Φ)*ρma+Φ*ρw; calculate the average density ρ of the formation to be 2.589g / cm 3 ;

[0050] 4) Determine the fracture pressur...

example 2

[0055] Example 2: Well JY13-2 in a shale gas field

[0056] Well JY13-2 is a horizontal well with a long horizontal section, the horizontal section of the gas reservoir is 2630-4078m, the vertical depth of the gas reservoir is 2330.0-2412.0m, and the horizontal section passes through the gas reservoir.

[0057] 1) Collect the conventional logging curve data (including acoustic wave, density, and neutron curve) of the whole well section of the well, and use the weighted average method to calculate the average rock skeleton density ρma of 2.67g / cm2 using the density logging curve data 3, the average porosity Φ of the formation is determined to be 0.05, and the fluid density ρw is 1.05g / cm by using the conventional logging curve data of the whole well section and the core porosity analysis data of the core well of the regional exploration well 3 ;

[0058] 2) Determine the well section of the shale gas reservoir to be 2630-4078m, and the vertical depth to be 2332.0-2412.0m, and ...

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Abstract

The invention relates to a shale gas reservoir formation fracture pressure gradient computing method. The method comprises the steps that conventional logging curve data of all sections of a well arecollected, the rock framework density rhoma is calculated, and the formation average porosity phi and fluid density rhow are determined; the depth, vertical depth, sound wave AC, density DEN and neutron CNL logging curve data of a shale gas well reservoir section are collected; the formation average density is calculated through the formula that rho=(1-phi)*rhoma+phi*rhow; and the fracture pressure coefficient K=P0+P1*AC+P2*DEN+P3*CNL through a fitted regression method, the shale gas reservoir formation fracture pressure gradient is computed according to the formula that FRAC=K*rho, then the fracture pressure is calculated through the formula that FP=FRAC*H, and the result is output finally. According to the method, more than 200 shale gas wells are applied to a shale gas field in Fuling,the computed formation fracture pressure gradient is close to the formation fracture pressure gradient obtained during actual construction, and the error is smaller than 15%.

Description

technical field [0001] The invention relates to a method for calculating and determining the fracture pressure of a shale reservoir formation by using conventional logging data, in particular to a method for calculating the fracture pressure gradient of a shale gas 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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B49/00E21B47/06
Inventor 廖勇李新勇石文睿袁明前邓章华毛琳
Owner 中石化石油工程技术服务有限公司