致密砂岩启动压力梯度确定方法研究  

Methods for Determining Threshold Pressure Gradient of Tight Sandstone

作　　者：高婧 李聪[1] GAO Jing;LI Cong(CNPC Jidong Oilfield Company,Tangshan 063200,Hebei,China)

机构地区：[1]中国石油冀东油田分公司,河北唐山063200

出　　处：《承德石油高等专科学校学报》2024年第6期13-16,70,共5页Journal of Chengde Petroleum College

摘　　要：低速非达西流是流体在致密砂岩中渗流时普遍存在的一种现象,一般常用启动压力梯度进行表征。为了准确获得南堡陆地岩芯的启动压力梯度,开展了4块岩芯的气水两相启动压力梯度实验,结果发现,气体的渗流速度与压力梯度之间表现出低速非线性渗流特征。通过绘制气体有效渗透率与平均压力倒数、气体流速与压力平方差之间的关系图,计算出启动压力梯度。同时建立4块岩芯对应的数值模型,分别模拟考虑毛管压力与不考虑毛管压力情况下的岩芯启动压力梯度。对比分析发现,实验计算的启动压力梯度大于模拟的启动压力梯度,考虑毛管压力得到的启动压力梯度远大于不考虑毛管压力得到的启动压力梯度,由此表明,毛管压力是引起启动压力梯度的最主要原因。Low-velocity non-Darcy percolation is a common phenomenon when the fluid flow in the tight sandstone,which is often characterized by the threshold pressure gradient.The 2-phase gas-water experiment is conducted on 4 cores to precisely obtain the value of threshold pressure gradient of oil field in Nanpu.Based on the experiment data,nonlinear percolation feature is shown between gas percolation velocity and pressure gradient.The threshold pressure gradient is calculated by plotting the relationship between gas effective permeability and the inverse of mean pressure as well as gas velocity and difference of pressure square curves.Meanwhile,the numerical model of 4 cores are built to model threshold pressure gradient considering and regardless of the capillary pressure.Results show that the measured value of threshold pressure gradient is greater than the simulated value,and the value considering capillary pressure is greater than the value regardless of capillary pressure.Eventually,we can conclude that the capillary pressure is the foremost factor causing the threshold pressure gradient.

关 键 词：低速非达西 启动压力梯度 毛管压力 岩芯数值模拟 

分 类 号：TE37[石油与天然气工程—油气田开发工程]