Activity calculating method suitable for fault of lost upthrown-side stratum

Abstract

The invention provides an activity calculating method suitable for a fault of a lost upthrown-side stratum. The method comprises the steps that the evolutionary process of the fault is recovered through a balanced section method; the target stratum is recovered to a state of the end of the depositional stage by using a back-stripping method; the thickness difference of target strata of two sidesof the fault after reconstruction is regarded as the paleo fall D; the fault dip angle and deposition time are determined; the slipping rate of the fault is obtained through calculation by using a formula to represent the activity of the fault. The quantitative evaluation method is simple and convenient to use, based on construction restoring, the influence of stratum loss is evaded, and meanwhile, three factors including the paleo fall, the fault tip angle and the deposition time are taken into consideration, so that the activity characteristics of the fault are more comprehensively reflected.

Description

technical field [0001] The invention relates to the technical field of oilfield exploration and development, in particular to an activity calculation method suitable for missing faults in upwelling wall formations. Background technique [0002] At present, the commonly used methods of fault activity include growth index method, fault drop method and fault activity rate method. These methods are mainly aimed at the well-developed growth faults inside the basin. For high-level faults such as boundary faults at the edge of the basin, because the upwelling strata are often denuded, the current evaluation methods have certain limitations. The growth index method uses the ratio of the upper and lower walls to the thickness of the strata to represent the activity of the fault, but the growth index cannot be used to evaluate the faults that have been eroded or not deposited in the upper and lower walls. Fault drop can effectively avoid the defect of growth index, but it does not re...

AI Technical Summary

Problems solved by technology

The growth index method uses the ratio of the upper and lower walls to the thickness of the stratum to represent the activity of the fault, but the growth index cannot be used to evaluate the denudation of the upper and lower walls or faults that have not accepted deposition.

Fault drop can effectively avoid the defect of growth index, but it does not reflect the concept of geological time, and cannot well represent the activity characteristics of faults in unit geological time

The fault activity rate method better combines the advantages of the former two, and can reflect the vertical activity intensity of the fault in a certain geological history. The results of the rate are the same, but the distance of the fault displacement is actually different

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