超深碳酸盐岩油气储层岩石弹性性质高温高压超声实验研究

High-temperature and high-pressure ultrasonic experimental studies on elastic properties of ultra-deep carbonate reservoir rocks

面向超深碳酸盐岩油气勘探开发中储层精细地震刻画问题,研发了高温(200℃)、高压(200 MPa)岩石弹性性质超声测量系统.收集塔里木盆地9块奥陶系超深碳酸岩储层岩石样品,通过高温高压条件下超声纵、横波速度测量发现,在围压保持69.0 MPa不变的情况下,当温度从25℃上升到200℃时,干岩石样品的纵、横波速度以及体积模量与剪切模量随着温度的升高而下降,纵波速度与体积模量最大降幅分别达到3.54%和7.54%,横波速度与剪切模量最大降幅分别达到4.57%和8.93%;在温度保持200℃不变情况下,当围压从69.0 MPa上升到137.9 MPa时,干岩石样品的纵、横波速度以及体积模量与剪切模量随着围压的升高而升高,纵波速度与体积模量最大升幅分别达到1.78%和3.39%,横波速度与剪切模量最大升幅分别达到1.95%和5.26%.在超深碳酸盐岩油气储层环境下,温度对碳酸盐岩岩石骨架弹性性质的影响可能超过围压对岩石骨架弹性性质的影响.岩石样品温度与围压循环实验表明,干岩石弹性性质与温度以及围压的变化关系不具可逆性,碳酸盐岩岩石样品弹性模量与温度之间总体上存在线性关系,其截距与斜率由碳酸盐岩岩石中方解石的含量控制.

A high-temperature(200℃)and high-pressure(200 MPa)ultrasonic measurement system of rock elastic velocities is developed for seismic characterization of ultra-deep oil and gas reservoirs.Nine carbonate rock samples of ultra-deep oil and gas reservoir in Tarim basin are collected for high-temperature and high-pressure ultrasonic measurements.It is found that the maximum decreases of P-wave velocity,S-wave velocity,bulk and shear modulus reach 3.54%,4.57%,7.54%and 8.93%,respectively,when temperature rises from 25℃ to 200℃ under the confining pressure of 69.0 MPa.The maximum increases of P-wave velocity,S-wave velocity,bulk and shear modulus reach 1.78%,1.95%,3.39%and 5.26%,respectively,when the confining pressure rises from 69.0 MPa to 137.9 MPa under the temperature of 200℃.In ultra-deep carbonate reservoir,the influence of temperature on the elastic properties of rocks is greater than that of confining pressure.Closed-loop temperature and confining pressure experiments show that elastic properties of carbonate rock samples varying with temperature and confining pressure are irreversible.There is a linear relationship between the elastic moduli of carbonate rock samples and temperature,and its intercept and slope are controlled by the content of calcite in carbonate rock samples.