中国南海某盆地A凹陷灰岩潜山有效裂缝预测

中国南海某盆地A凹陷灰岩潜山经历了多期次构造运动,形成了大量构造裂缝.早期形成的构造裂缝经历了漫长地质历史时期的剥蚀、风化,并遭受大气降水、地表径流的淋滤和溶蚀,构造裂缝有的被溶蚀扩大,有的被方解石半充填或完全充填;而后期构造运动产生的裂缝,则往往未被充填,成为沟通溶蚀孔、洞的主要通道.利用应变量分析的方法,对该凹陷的构造发育史进行反演和正演,计算每期构造运动对潜山地层产生的应变量,从地质成因的角度对每期构造运动产生的三维裂缝网络进行预测,从而将早期潜山形成期形成的充填裂缝与后期形成的末充填有效裂缝区分开,达到预测灰岩潜山裂缝型储集层的目的.图5参14

Prediction of effective fractures in a limestone buried hill, South China Sea

Because of the strong tectonic movement during the formation of a limestone buried hill in the A sag, lots of fractures occured. The early formed structural fractures have undergone denudation, demorphism, leaching, dissolution from atmosphere precipitation and surface runoff, which make some of the initial structural fractures enlarged and some half-filled or full filled with calcite. The fractures formed in the later tectonic movement are generally not filled and become the main channel connecting dissolution pores with cavities. This paper calculates the strain magnitude of buried hill formations resulting from every tectonic movement using strain analysis methods such as the inversion and forward modeling of structural evolution history of formations, predicts the 3D fracture network formed in every tectonic movement from the geological genesis standpoint, and therefore, distinguishes the early filled fractures formed in the period of the buried hill formation from the unfilled fractures formed later, achieving the goal of predicting fracture reservoirs in the limestone buried hill.