地层压力基本知识

1、目目 录录前言前言一、孔隙压力术语一、孔隙压力术语二、温压场的划分二、温压场的划分三、国内外研究现状三、国内外研究现状四、异常压力预测的发展趋势四、异常压力预测的发展趋势五、异常高压的成因机制五、异常高压的成因机制斜率斜率(slope) 纯水纯水g/cm3 盐水盐水g/cm3) 地层水：地层水：psi/ft 1g/cm3 = .433 pst/ft开放系统开放系统(open system)a column of water固体固体+流体流体美国海湾盆地水饱和的沉积岩密度为g/cm3，静岩压力梯度为：.433psi/ft2.3g /cm3异常高压发生在静岩异常高压发生在静岩压力梯度线和清水静压力

2、梯度线和清水静压梯度线之间的区域压梯度线之间的区域PressureDepthThe “pore pressure” is the pressure of the fluid in the pore space of the rock.The point at which pore pressures exceed hydrostatic pressures is the “top ofoverpressures.”In overpressure, fluids are trapped in the pores and bear part of the weight of the overlyi

3、ng solids.Any pressure over the hydrostatic pressure is overpressure（超压）. The amount of pore pressure exceeding the hydrostatic line.Effective stress（有效应力） is the amount of overburden stress that is supported by the rock grains.Typical trend curves for resistivity, sonic velocity, and density. Blue

4、curves denote normal compaction trends. Arrows indicate deviations due to overpressure.Cross-section of hypothetical reservoir unit. In the absence of fluid flow, the difference in pore pressure between points A and B is simply the weight of the fluid in the vertical reservoir column.A local pressur

5、e gradient defines how pressure varies over small depth ranges. At the smallest scale, it equals the slope of a pressure versus depth curve. The most basic pressure gradient that we use is equivalent mud weight (EMW).Pressure profile for hypothetical reservoir unitPressure plotted against depth with

6、 mud weight scale added1 lb/gal = .0519 psi/ft*气体气体=84.3%C1+14.4%C2+0.5%CO2+0.8%N2Diagram illustrating pore pressure between hydrostatic gradient and fracture gradientUsing mud weight changes pressure axis to gradient axis. This is the view preferred by drillers.Casing points and mud weight profile

7、for hypothetical situationSimple illustration of lateral transfer when one side of a basin subsides and fills with shale. Overburden in the subsided portion is higher and, if burial is sufficiently fast that the shale cant dewater quickly enough, it becomes overpressured. This is known as disequilibrium compaction. a. 单一型温单一型温压系统压系统 b.高压型复式温高压型复式温压系统压系统 c.低压型复式温低压型复式温压系统压系统 -4 0 4压力系数地温异常（）济阳坳陷温济阳坳陷温压系统平面分区标准压系统平面分区标准Pore structure models used to characterize shale behavior. Pores with aspect ratios in the 0.001-0.1 range undergo most rebound. Higher