辽河盆地大民屯凹陷流体压力场研究

综合利用泥岩声波时差、实测地层压力和地震资料 ,分析了辽河盆地大民屯凹陷的地下流体压力场特征 .研究结果表明 :(1)本区泥岩压实类型可划分为正常压实 -常压型、单段欠压实 -弱超压型和双段欠压实 -强超压型三大类 ;(2 )油层压力梯度接近于 1,多属正常压力系统 ;(3)利用地震资料研究平、剖面压力场特征具有较高的可行性与可靠性 ;(4)现今剖面压力系统由浅部正常压力、中部弱超压和深部强超压 3个部分组成 ,断裂系统、不整合面和相互连通的孔隙系统及底辟构造组成了凹陷内流体纵、横向输导的复杂网络系统 ;(5 )规模较大断层两侧的剩余压力和压力系数具较明显的差异性 ,断层对压力的形成、演化与分布起着重要的控制作用 ;(6 )欠压实与烃类生成是本区超压形成的主导机制

RESEARCH INTO FLUID PRESSURE FIELD IN DAMINTUN DEPRESSION, LIAOHE BASIN

The mudstone sonic log interval, measured stratigraphic pressure and seismic data are integrated to analyze the underground fluid pressure fields in Damintun depression, Liaohe basin. The research results show the following six points: (1) The mudstone compaction in this region is classified as the following three types: normal compaction_normal pressure, under_compaction and low overpressure in one single interval, and under_compaction and high overpressure in double intervals. (2) The pressure gradient of the oil layers is approximate to 1, so it is often within the normal pressure system. (3) The characteristics of planes and profile pressure fields obtained through the seismic data are of a higher feasibility and reliability. (4) The current profile pressure system consists of normal pressure, low overpressure, and high overpressure from surface to the deep layers. The fault systems, unconformity surfaces, interconnecting pore systems and diapir structures constitute the complex network system of vertical and horizontal transportation within the depression. (5) A distinctive difference exists between the surplus pressures and pressure coefficients on both sides of the relatively large_scale faults controlling greatly the formation, evolution and distribution of the pressures. (6) The under_compaction and hydrocarbon generation are the leading mechanisms for the formation of the overpressure in this region.