库车坳陷东部异常流体压力特征及其对构造变形的控制

Characteristics of abnormal fluid pressure in eastern Kuqa depression and its control on tectonic deformation

为探究库车坳陷东部异常流体压力特征及其对构造变形的影响，在研究区25口井的钻井、完井及测井资料基础上，利用“等效深度法”计算出泥岩段流体压力，并结合实测流体压力对其进行校正，从而刻画出该地区依奇克里克构造带、秋里塔格构造带以及阳霞凹陷超压发育特征，在此基础上拟合流体压力随深度的变化规律，估算出在依奇克里克构造带以及秋里塔格构造带基底滑脱层有效摩擦系数为0．138—0．238；通过解释过井的地震剖面，运用构造楔相关理论计算出基底滑脱层强度F=0．1．034-0．1729，将其与利用基底滑脱层流体压力比计算出来的有效摩擦系数进行比较，发现两者之间存在比较好的吻合性，以此证明估算基底滑脱层有效摩擦系数的可信度；计算出若研究区不发育流体超压，则基底滑脱层有效摩擦系数应为0．342—0．485，说明研究区广泛发育的流体超压有效降低了原基底滑脱层有效摩擦系数的59．1％-69.8％，意味着在研究区沿基底滑脱层发生剪切作用所需要的构造应力大幅度减小。

In order to study the characteristics of abnormal fluid pressure in eastern Kuqa depression and its influence on tectonic deformation, we calculated the fluid pressure in mudstone interval of 25 wells in study area by using ＂equivalent depth method＂, based on the drilling data, logging data and well completion data. Correcting the calculated fluid pressure according to the measured fluid pressure and depicting the characteristics of abnormal fluid pressure of different tectonic belts in study area, by which, we fitted the relationship between fluid pressure and depth and estimated the effective coefficient of friction of the basal fault g~~ is 0.138 ~ 0.238. Calculated the strength of basal fault F （should be equal to pb＇） is 0.103 4 ~ 0.172 9 by using ＂critical-taper wedge mechanics＂, based on the seismic section A-A＇, B-B＇. There is a good agreement between effective coefficient of friction of basal fault gb＊ and basal fault strength F, which indicated that calculated effective friction coefficient of the basal fault is dependable. If there is no fluid overpressure in study area, the effective coefficient of friction of the basal fault should is 0.342- 0.485, explained that it is the widely developed fluid overpressure in the study area that effectively reduced the effective friction coefficient of the basal fault 59.1% 69.8%, which means the required shear stress to make shear failure occurred reduce by a large margin in Yiqikelike belt and Qiulitage tectonic belt.