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识别气层的普通方法是以中子测井孔隙度与密度测井孔隙度比较为基础。在低孔隙度、变化的骨架地层中,识别气层常常是困难的。本文提出的测井识别气层新方法,首先是用声波测井、密度测井和中子测井信息计算岩石等效弹性模量差比值(EDR),然后用它评价天然气层。计算岩石等效弹性模量差比值的公式如下:EDR=E_(cw)-E_c/E_e式中EDR——岩石等效弹性模量差比值,无量纲;E_c——岩石等效弹性模量,达因/cm~2;E_c——完全含水岩石等效弹性模量,达因/cm~2。在一般情况下,当岩石等效弹性模量小于完全含水岩石等效弹性模量时,岩石等效弹性模量差比值大于零,指示是气层;反之,当岩石等效弹性模量等于完全含水岩石等效弹性模量时,岩石等效弹性模量差比值等于零,指示是非气层。该方法用于评价砂岩气层与碳酸盐岩气层,提高了测井直观识别气层的分辨率和解释精度。
The common method for identifying gas layers is based on a comparison of neutron well logging porosity and density well logging porosity. In low porosity, variable skeleton formations, identifying the gas zone is often difficult. In this paper, a new method of well logging identification gas reservoir is first to calculate the rock equivalent elastic modulus difference (EDR) by using sonic logging, density logging and neutron log information, and then use it to evaluate the gas layer. The formula for calculating the ratio of equivalent elastic modulus of rock is as follows: EDR = E_ (cw) -E_e / E_e where EDR is the ratio of equivalent elastic modulus of rock, dimensionless; E_c is the equivalent elastic modulus of rock, Dyne / cm ~ 2; E_c - equivalent elastic modulus of fully aqueous rock, dyne / cm ~ 2. In general, when the equivalent elastic modulus of rock is less than the equivalent elastic modulus of a completely hydrated rock, the ratio of equivalent elastic modulus of rock is greater than zero, indicating that it is a gas layer. On the contrary, when the equivalent elastic modulus of rock is equal to complete When the equivalent elastic modulus of water-bearing rock is equal, the ratio of equivalent elastic modulus of rock is equal to zero, indicating that it is non-gas-bearing. The method is used to evaluate sandstone gas reservoirs and carbonate gas reservoirs, and to improve the resolution and interpretation precision of log gas reservoirs.