东濮凹陷柳屯洼陷沙三上亚段流体压力场研究

Research into Fluid Pressure Field of Upper Part Es_3 in Liutun Sag,Dongpu Depression

流体压力场分布特征对泥岩裂缝油藏勘探和开发具有非常重要的作用,而盐间地层的压力分布有其特殊性。综合利用钻井、泥岩测井声波时差和地震资料,分析了东濮凹陷柳屯洼陷沙三上亚段的流体压力场特征,为该盐间泥岩裂缝油藏的进一步研究奠定了基础。研究结果表明:①本区沙三上亚段压力结构可划分为正常-渐变-弱超压型和正常-突变-强超压型两大类;②盐间泥岩裂缝油藏位于洼陷超高压力系统内;③现今沙三上亚段压力剖面具有东西分异、上下分带、受控于膏盐岩分布的特点,各类型裂缝和膏盐岩形成的微构造组成了该亚段纵横向的复杂输导网络系统;④膏盐岩封盖和石膏脱水是影响本区超压发育的重要机制之一,并造成了洼陷东西两侧流体压力场特征的差异。

The fluid pressure field distribution plays a very important role on the exploration and development of fractured mud reservoir,while pressure field distribution in inter salt formations has its particularity.The drilling data,acoustic transit time of mudstone and seismic data are integrated to analyze the fluid pressure field of upper part Es3in Liutun Sag,Dongpu Depression,which lay a foundation of further study on this inter salt fractured mud reservoir.Following five points are derived from the research：（1）the pressure structure of upper part Es3in this region is divided into two types：normal-gradual change-low overpressure,and normal-abrupt change-high overpressure.（2）The inter salt fractured mud reservoir is located in the region of ultrahigh pressure system in Liutun Sag.（3）The current pressure profile of upper part Es3in Liutun Sag is characterized by the difference between west and east,zoning from the top to the bottom,and controlled by the distribution of gypsum-salt rock.The various types of fractures,coupled with micro-structures created by gypsum-salt rock,constitute the complex network system of vertical and horizontal transportation within upper part Es3.（4）Sealing with gypsum-salt rock and gypsum dehydration are two leading mechanisms to form the overpressure in the region of interest,and make the difference of fluid field pressure between west and east in Liutun Sag.