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Shale reservoir gas saturation determining method based on TOC

A technology for shale reservoirs and determination methods, which is applied in the direction of earthwork drilling and production, wellbore/well components, etc., and can solve the problems of poor reliability, reduced resistivity of shale reservoirs, and gas saturation of shale reservoir resistivity Low accuracy and other problems, to achieve the effect of wide application range and low cost

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

[0004] The prerequisite for calculating the gas saturation of shale reservoirs by the Archie method is that only formation water conducts electricity, and the mineral components constituting the formation framework do not conduct electricity. However, the content of conductive mineral pyrite and formation bound water in shale reservoirs is relatively high , leading to an abnormal decrease in the resistivity of the shale reservoir, and the calculated gas saturation of the resistivity of the shale reservoir has low accuracy and poor reliability

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  • Shale reservoir gas saturation determining method based on TOC
  • Shale reservoir gas saturation determining method based on TOC

Examples

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example 1

[0037] Example 1: Well A in Jiantian gas field

[0038] 1) Obtain TOC data through geochemical logging instrument measurement;

[0039] 2) The data recording step of mud logging TOC curve is 1 point / m;

[0040] 3) In the 610.0-645.0m well section of Jurassic Dongyuemiao section, the lithology is mainly shale. Total hydrocarbons and methane increased from the base value of 0% to 9.85%. According to gas logging total hydrocarbons, drilling time and logging natural gamma ray, density curves, etc., this interval was divided into shale reservoirs, and element logging showed no conductive The mineral pyrite.

[0041] 4) Read the TOC data of the 610.0-645.0m well section, and the value is between 1.0% and 2.0%;

[0042] 5) The 600.0-610.0m shale TOC above 610.0m is 0.1%-0.3%, 0.2% on average, and the TOC background value TOCb of the shale reservoir in the 610.0-645.0m section is 0.2%, that is, TOCb=0.2%;

[0043] 6) The value of n is determined according to the regional experimen...

example 2

[0047] Example 2: Well B in the Fuling shale gas field,

[0048] 1) Obtain TOC data through logging data calculation;

[0049] 2) The logging step of TOC curve data is 1 point / 0.1m;

[0050] 3) The lower part of the Silurian Longmaxi Formation - Ordovician Wufeng Formation 2340.0-2415.0m well section, the lithology is mainly carbonaceous shale, the total hydrocarbon and methane increased from the base value of 0.10% to 2.13%, according to the total hydrocarbon , Drilling time and logging natural gamma ray, density curve, etc. divide this interval into shale reservoirs;

[0051] 4) Read the TOC data of the 2340.0-2377.0m well section, the value is 1.0%-2.0%, and the TOC data of the 2377.0-2415.0m well section, the value is 2.0%-4.6%. The element mud logging shows that the conductive mineral pyrite is locally contained, Pyrite content is 2.0% to 5.0%;

[0052] 5) The 2330.0-2340.0m shale TOC above 2340.0m is 0.1%-0.3%, with an average of 0.2%, and the 2340.0-2415.0m shale res...

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Abstract

The invention relates to a shale reservoir gas saturation determining method based on TOC. The method includes acquiring TOC data through measurement of a geochemical logging instrument or calculation of log data; diving shale gas reservoirs according to formation lithology, gas logging methane, drilling time, logging natural gamma rays, density curve changes, reading shale reservoir TOC curve data, selecting an adjacent non reservoir TOC average in the same shale segment to serve as a TOC background value of the shale reservoir, selecting regional shale reservoir gas saturation index n according to different region classifications, figuring out gas saturation Sg according to a formula that Sg = 1-(TOC t / TOC b)-1 / n, and outputting the result. By the aid of the method, the problem of calculation of formation gas saturation of low-resistant shale reservoirs is solved, cost is low, and the method is facilitated, accurate and wide in the applying range; the method is applied in 26 wells in the Fuling shale gas field and is used for explaining and processing 23 wells of low-resistant shale reservoirs, and accuracy is determined.

Description

technical field [0001] The invention relates to a method for determining the gas saturation of shale reservoirs in the process of mud logging and well logging interpretation, and provides key parameters for interpretation for shale reservoir evaluation to determine the gas saturation of TOC shale reservoirs. Background technique [0002] In the process of mud logging and logging services in shale gas exploration and development, the traditional method for determining the gas saturation of shale gas reservoirs is the Archie method. [0003] The Archie method is used to obtain the gas saturation of shale reservoirs, mainly using the logging data of shale reservoir resistivity, porosity, and regional formation water resistivity, and using Archie's formula to obtain it. The gas saturation of shale and other reservoirs calculated based on the Archie method is called "resistivity gas saturation". [0004] The prerequisite for calculating the gas saturation of shale reservoirs by ...

Claims

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Application Information

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IPC IPC(8): E21B49/00
Inventor 张建平冯爱国石元会任元肖世匡赵红燕田芳石文睿李光华
Owner CHINA PETROCHEMICAL CORP
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