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Method for recognizing sweet spots in shale stratum

A shale and formation technology, applied in the field of identifying sweet spots in gas-bearing shale formations, can solve the problems of parameter description and definition of engineering sweet spots, undifferentiated geological sweet spots and engineering sweet spots, etc.

Active Publication Date: 2016-10-05
CHINA PETROLEUM & CHEM CORP +1
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Problems solved by technology

However, usually only the brittleness index is used to characterize engineering sweets, and there are no reasonable parameters to describe and define engineering sweets
[0007] In addition, at present, geostatistical methods are usually used to describe sweet spots, mainly counting parameters such as brittle mineral content, thermal maturity, organic matter content, net thickness, burial depth, gas content and water saturation of shale formations, but these parameters are not distinguished Geological Sweets and Engineering Sweets

Method used

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  • Method for recognizing sweet spots in shale stratum
  • Method for recognizing sweet spots in shale stratum
  • Method for recognizing sweet spots in shale stratum

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Embodiment 1

[0099] Firstly, the technical idea of ​​identifying geological sweet spots is explained.

[0100] figure 1 A technical idea for identifying geological sweet spots in this embodiment is shown. The ideal identification method of geological sweet spot parameters requires accurate evaluation of each geological sweet spot parameter with existing logging methods. The porosity of shale formations is small, and conventional three-porosity logging methods (acoustic, neutron and density logging) are difficult to accurately evaluate the porosity of shale formations due to the influence of multi-mineral and organic matter instability , NMR logging methods are needed to accurately evaluate formation porosity and irreducible water content, wherein formation porosity includes movable gas porosity and movable water porosity. The element logging method can effectively judge the complex mineral types and contents of shale formations, and obtain other geological sweet spot parameters that are ...

Embodiment 2

[0191] In this embodiment, the logging data of a well in a shale formation in a block in southwest China is used as an example to illustrate the identification result of a shale formation sweet spot.

[0192] The lithology of high-quality shale in this block is mainly composed of yellow-gray shale and silty shale interbedded with thin lenticular limestone. Geological sweet spot parameters and engineering sweet spot parameters are shown in Table 1. In Table 1, TOC is total organic carbon content, Φg is gas-bearing pores; Vk is kerogen volume; Sg is gas saturation; BRI is brittleness index; σ is effective stress, and b is pore structure index.

[0193] Table 1 Statistical table of sweet spot coefficients in Jiaoshiba shale formation

[0194]

[0195] according to Figure 9 As shown in the radar map, the geological sweet spot coefficient can be determined to be 0.72, according to Figure 10 As shown in the radar chart, the engineering sweet spot coefficient can be determine...

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Abstract

The invention discloses a method for recognizing sweet spots in a shale stratum. The method includes the following steps that the kerogen volume content, the gas-bearing porosity, the gas saturation and the total organic content of the shale stratum are determined according to logging information, and the geological sweet spot coefficient of the shale stratum is obtained through a radar map analyzing method; the maximum horizontal effective stress value, the pore structure index and the brittleness index of the shale stratum are determined according to the logging information, and the engineering sweet spot coefficient of the shale stratum is obtained through the radar map analyzing method; and the sweet spots in the shale stratum are recognized according to the geological sweet spot coefficient and the engineering sweet spot coefficient. According to the method, the geological sweet spots and the engineering sweet spots in the shale stratum are quantitatively represented according to the geological sweet spot coefficient and the engineering sweet spot coefficient, and the sweet spots in the shale stratum can be determined through comprehensive analysis of the two coefficients; and the development cost can be lowered by exploration and development in sweet spot areas, and the development efficiency of shale gas is improved.

Description

technical field [0001] The invention relates to the technical field of geological exploration, in particular to a method for identifying sweet spots in gas-bearing shale formations. Background technique [0002] The sweet spot in the shale formation refers to the part of the formation that has good reservoir geological quality and is relatively easy to perform fracturing engineering. The sweet spot is very important to the development of shale formations. Finding the sweet spot is conducive to reducing the cost of shale exploration and development and increasing the productivity of gas-bearing shale formations. [0003] The term "sweet spot" first appeared in relation to difficult-to-develop reservoirs, and refers to a small fault block in conventional oil and gas layers with good reservoir quality. It was subsequently used in coalbed methane, where sweet spots are high potential gas producing areas with better natural fractures and coal seam thickness, and higher formation...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B49/00
Inventor 廖东良曾义金
Owner CHINA PETROLEUM & CHEM CORP
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