Method of judging low-resistivity annulus formed in formation

A low-resistance annular zone and formation water resistivity technology, applied in the field of oil and gas reservoir identification, can solve problems such as unfavorable low-resistance oil and gas exploration and development, inability to intuitively describe mud, low-resistance oil and gas reservoir leakage, etc., and reduce exploration and development costs. , the effect of saving exploration costs and improving the extraction rate

Active Publication Date: 2014-02-19
CHINA PETROLEUM & CHEM CORP +1
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Problems solved by technology

However, due to the very strict conditions for the formation of low-resistivity rings, it cannot be guaranteed that every well will have low-resistivity rings if this method is not used. Other logging methods lead to increased exploration costs. The patent "A Method for Optimizing Drilling Mud to Quickly Identify Low-resistivity Oil and Gas Layers" proposes a mud design method, which cannot intuitively describe the relationship between mud resistivity and the conditions for forming low-resistance zones. , so the existing technology is not conducive to the exploration and development of low-resistivity oil and gas layers

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  • Method of judging low-resistivity annulus formed in formation
  • Method of judging low-resistivity annulus formed in formation

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example 1

[0031] Example 1: Identification of low-resistivity oil and gas reservoirs in mature areas

[0032] A well is located in an old exploration block, and the deep detection resistivity value is very low, the resistivity value is less than 1.5Ω·m, and the low resistivity is caused by high salinity, which is a typical low-resistivity oil and gas reservoir caused by high salinity. The irreducible water saturation of the core is 31.6%, and the residual oil saturation is 20%. The formation water analysis report shows that the water type is calcium chloride, and the total salinity is 154232mg / L, which translates into a formation water resistivity of 0.034Ω·m. According to the chart, find out that the condition for forming a low-resistance ring is R mf / R w >5.5, the actual drilling mud resistivity is 0.45Ω·m, then the mud resistivity R mf and formation water resistivity R w The satisfying relation between is: R mf / R w =13.2>5.5, far satisfying the conditions for forming a low-res...

Embodiment 2

[0033] Example 2: Discovery of low-resistivity oil and gas reservoirs in new areas

[0034] The resistivity value of the reservoir in a certain well is lower than that of the upper and lower surrounding rocks, which belongs to the low-resistivity oil-gas layer with lower resistivity than the surrounding rocks. It is difficult to identify the oil-water layer, and no judgment has been made before this layer. Inductive logging of parameters such as high frequency in array induction shows that the resistivity of the flushing zone is 10Ω·m, and the resistivity of the formation is 8Ω·m. The resistivity of the flushing zone is greater than the resistivity of the formation. However, the resistivity of the intrusion zone is 6.5 Ω·m, and the resistivity of the intrusion zone is the lowest, indicating that a low-resistance ring zone is formed in the formation, and the reservoir contains oil and gas, and the comprehensive analysis judges that oil and water are in the same layer. The test ...

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Abstract

The invention belongs to the technical field of petroleum exploration and development, in particular to an oil and gas reservoir recognition method applied to qualitatively analyzing existence of oil reservoirs through detection data, and provides a method of judging a low-resistivity annulus formed in a formation. The method includes: acquiring core data and determining irreducible water saturation Swb and residual oil saturation Sor of a core; acquiring a ratio of drilling fluid resistivity Rmf and formation water resistivity Rw according to the irreducible water saturation Swb and residual oil saturation Sor of the core; detecting a target formation to acquire the formation water resistivity Rw and the drilling fluid resistivity Rmf; if an actual physical value is larger than a calculated value, determining the low-resistivity annulus is formed. Through the application of the method in low-resistivity oil and gas fields, efficiency of exploiting low-resistivity oil and gas reservoirs can be improved effectively, the low-resistivity oil and gas reservoirs are recognized visually and quickly, exploration cost is reduced, and economic benefit is increased. As China possesses many low-resistivity oil and gas reservoirs, the method has promising application prospect.

Description

technical field [0001] The invention belongs to the technical field of petroleum exploration and development, and in particular relates to a method for identifying oil and gas reservoirs, that is, how to qualitatively analyze the existence of oil layers through detection data. Background technique [0002] In the technology of judging low-resistivity oil and gas layers, the low-resistivity ring refers to the resistivity of the flushing zone in the reservoir, the resistivity of the transition zone and the resistivity of the original formation. When the resistivity of the transition zone is the lowest, the transition zone of the reservoir is called low-resistivity. ring belt. When a low-resistance ring zone is detected in the formation, it means that there is oil and gas in the formation. This has long been confirmed by the logging community. Some people have also verified through experiments that during the process of mud invasion into the formation, there will be a low-resis...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B49/00
Inventor 廖东良陆黄生赵文杰吴海燕张元春王卫刘江涛李永杰刘双莲
Owner CHINA PETROLEUM & CHEM CORP
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