Method for quantitatively evaluating sealing ability re-forming time of cap rocks after fault movement

Abstract

The invention relates to a method for quantitatively evaluating the sealing ability re-forming time of cap rocks after fault movement. The cap rocks after fault movement lost self sealing ability, through overburden sediment load compaction, the sealing ability of the cap rocks recovers. According to a fault vertical sealing mechanism, the cap rocks after fault movement can re-form the sealing ability only when displacement pressure of the cap rocks after fault filler compaction is not smaller than displacement pressure of reservior rocks, and sealing ability gradually increases along with increase of a compaction degree of fault rocks. Based on the principle of the method, for a set of determined reservior rocks, required initial displacement pressure of the fault rocks is determined according to the displacement pressure of the reservoir rocks when the cap rocks re-form the sealing ability, burial depths of the fault rocks during formation of the sealing ability and surrounding rocks having the same diagenesis degree as the fault rocks are determined according to relationships between a product of shale content of the fault rocks established in a research zone and compaction diagenetic depth and the displacement pressure, and the sealing ability re-formation time of the cap rocks after fault movement is lastly acquired.

Description

[0001] Technical field: [0002] The invention relates to a quantitative evaluation method for the time of re-forming the sealing ability of the cover layer after being dislocated by a fault, which is applied in the field of geophysical exploration. [0003] Background technique: [0004] A large number of oil and gas exploration practices and theoretical studies of petroleum geology have confirmed that the sealing ability of cap rocks to oil and gas depends not only on their own sealing properties, but more importantly on the sealing ability of their faults. For the cap rocks that have been dislocated by faults but not yet dislocated, although the faults did not cause them to lose the continuity of their lateral distribution, due to the mutual grinding of the upper and lower plates of the fault, the diagenetic rocks that have fallen into the fault zone and have already occurred The affected rocks were fragmented again, and the degree of diagenesis was reduced, resulting in the...

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Problems solved by technology

Based on this, there is no effective method for determining the formation period of fault sealing ability, that is, there is no systematic and effective method for the research on the re-formation sealing ability time of the caprock after being dislocated by faults, which is undoubtedly not conducive to the evaluation of the sealing ability of faults. Faults destroy the sealing ability of cap rocks during the oil and gas accumulation period, which is not conducive to the in-depth oil and gas exploration in fault-developed areas of oil and gas basins

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