Isochronal interface recovery method in last phase of mid-term deposition cycle of fluvial facies stratum

Abstract

The invention relates to an isochronal interface recovery method in the last phase of mid-term deposition cycle of the fluvial facies stratum. The method comprises the following steps that 1) an undercutting sign is identified, and an undercutting position of a post river is determined; 2) the undercutting depth of the post river is obtained; and 3) an isochronal stratum interface in last phase of mid-term deposition cycle is recovered. According to the invention, the undercutting position of the post river is identified according to logging and earthquake integrated response and sand body growth characteristics by taking a reference surface cycle theory in high-resolution sequence stratigraphy as guidance, an identification result is objective and reasonable, and and the multiplicity of solutions is reduced.

Description

technical field [0001] The invention relates to a method for recovering an isochronous interface at the end of a mid-sedimentary cycle of a fluvial stratum, and belongs to the field of oil and gas field development. Background technique [0002] Fluvial facies strata change rapidly laterally and have strong heterogeneity. The isochronous division and correlation of the strata has always been the focus and difficulty in the development of oil and gas fields. [0003] In recent years, with the introduction of the principle of high-resolution sequence stratigraphy into China, the sequence division and stratigraphic isochronal correlation technology based on base-level cycles and the ratio of accommodating space to sediment recharge flux has been gradually applied. The isochronism of flooded mudstone interfaces and internal sequence boundaries at the end of sedimentary cycles, and their control on sandbody types, superposition styles, sedimentary sequences, and geometries in sho...

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Problems solved by technology

[0004] However, a complete sedimentary cycle consists of an ascending half-cycle and a descending half-cycle. When the base level falls, the river has a strong ability to erode and cut down. After a middle-term sedimentary cycle ends, the late flood mudstone is often eroded by the later-stage river downcutting. Destroyed, the preserved flooded mudstone interface is not isochronous, so it is difficult to be used as a benchmark for isochronous stratigraphic comparison

For the restoration of the isochronous interface at the end of the mid-sedimentary cycle, domestic theoretical circles have done some research work, but no substantial progress has been made

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