新疆石油地质

›› 2018, Vol. 39 ›› Issue (3): 1-1.doi: 10.7657/XJPG20180305

• 论文 •    

川东北部异常流体压力对构造变形的控制作用

范慧达，何登发，张旭亮   

  1. (中国地质大学 能源学院,北京 100083)
  • 出版日期:2019-01-01 发布日期:1905-07-16

Controls of Abnormal Fluid Pressure on Tectonic Deformation in Northeastern Sichuan Basin

FAN Huida, HE Dengfa, ZHANG Xuliang   

  1. (School of Energy Resources, China University of Geosciences, Beijing 10083, China)
  • Online:2019-01-01 Published:1905-07-16

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摘要： 为探究川东北部异常流体压力对构造变形的影响，以研究区40口井钻井、完井及测井资料为基础，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，从而刻画出研究区超压发育特征，拟合流体压力随深度的变化规律，计算不同滑脱层流体压力比：下三叠统嘉陵江组膏盐岩滑脱层流体压力比为0.38~0.72，下志留统龙马溪组页岩滑脱层流体压力比为0.48~0.78，下寒武统龙王庙组膏盐岩滑脱层流体压力比为0.61~0.87，基底滑脱层流体压力比为0.71~0.84，整体呈现东低西高的特征。利用各滑脱层流体压力比计算得到有效摩擦系数，嘉陵江组膏盐岩滑脱层有效摩擦系数为0.170~0.530，龙马溪组页岩滑脱层有效摩擦系数为0.130~0.320，龙王庙组膏盐岩滑脱层有效摩擦系数为0.110~0.330，基底滑脱层有效摩擦系数为0.090~0.180.通过解释过井地震剖面，运用构造楔相关理论计算出基底滑脱层强度为0.060~0.110，将其与有效摩擦系数进行对比发现，两者之间存在较好的吻合性，证明计算得到的基底滑脱层有效摩擦系数较可靠。研究区不发育流体超压时，基底滑脱层有效摩擦系数应为0.372~0.527，说明研究区广泛发育的流体超压导致原基底滑脱层有效摩擦系数降低了79.1%~83.9%，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。

Abstract: To investigate the influences of abnormal fluid pressure on structural deformation in the northeastern Sichuan basin, on the basis of drilling and logging data obtained from 40 wells in the study area, the paper uses equivalent depth method to calculate fluid pressure in the shale section and corrects the pressure by combining with the actual measured fluid pressure to characterize the characteristics of the overpressure development in the study area and to match the variations of the fluid pressure with depth. The pore-fluid pressure ratio of different detachment layers in the northeastern Sichuan basin are calculated. The calculated pore-fluid pressure ratio is 0.38~0.72 for the gypsum-salt detachment layer in the Lower Triassic Jialingjiang formation, 0.48~0.78 for the shale detachment layer in the Lower Silurian Longmaxi formation, 0.61~0.87 for the gypsum-salt detachment layer in the Lower Cambrian Longwangmiao formation and 0.71~0.84 in the basement detachment layer, showing a feature of “lower in the east and higher in the west”. The pore-fluid pressure ratio of each detachment layer is used to obtain effective friction coefficient and the calculated effective friction coefficient of each detachment layer is 0.170~0.530, 0.130~0.320, 0.110~0.330 and 0.090~0.180 for Jialingjiang formation, Longmaxi formation, Longwangmiao formation and basement, respectively. Based on the through-well seismic profile interpretation, the intensity of the basement detachment layer is calculated as 0.060~0.110 by using structural wedge-related theories. Comparing the intensity with the effective friction coefficient, it is found that they are identical with each other, which can prove that the calculated effective friction coefficient of the basement detachment layer is reliable. When the fluid overpressure is not developed in the study area, the effective friction coefficient of the basement detachment layer should be 0.372~0.527, which indicates that the widely-developed fluid overpressure in the study area results in the reduction of the effective friction coefficient of the basement detachment layer by 79.1%~83.9%, indicating that the tectonic stress needed by shear action along the basement detachment layer significantly decreases

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