摘要
弹性二相法作为计算气驱、低渗气藏单井控制范围内地质储量、技术可采储量的方法,在天然气勘探阶段估算探井控制储量或投产初期核实气藏储量时发挥着重要的作用,但标准中常用的简化公式未给出适用条件,导致气井单井控制储量出现偏差。为此,基于有界气藏中一口直井在拟稳定流动阶段的无量纲解析解,详细推导给出了气井弹性二相法压力法、压力平方法、拟压力法和规整化拟压力法形式的有量纲计算公式,对表达式简化过程中存在的问题进行了分析,并提出了解决方案,最后分别进行了模拟实例和矿场实例的综合验证。研究结果表明:①当地层压力低于20.1 MPa时气体压缩系数可简化为1/pi,弹性二相法计算公式可进行简化;②当地层压力高于20.1 MPa时,应直接采用原始压力或计算最高压力情形下的气体压缩系数值,或采用1/pi简化与修正系数并举的方式;③(规整化)拟压力法是首选方法,低压(<13.8 MPa)情形不宜采用压力法。结论认为:①对于低渗、致密气藏,经常出现流压与时间呈线性关系但未达到拟稳定流动的现象,此时应慎用弹性二相法;②若有压力恢复数据,建议将压降与压力恢复数据(反褶积分析)结合起来评价储量。
The elastic two-phase method,as a way to calculate the geological reserves and technically recoverable reserves within the single-well control range of low-permeability gas reservoir by gas driving,plays an important role in estimating the controlled reserves of exploration wells in the natural gas exploration stage or verifying the reserves of gas reservoirs in the early stage of production.However,the applicable conditions of the commonly used simplified formulas are not defined,which causes deviations in the single-well controlled reserves of gas well.Based on the dimensionless analytical solution of a vertical well in a bounded gas reservoir during the pseudo-steady flow stage,this paper derives and presents in detail the dimensional calculation formulas in the forms of pressure method,pressure square method,pseudo-pressure method and normalized pseudo-pressure method of the elastic two-phase method for gas wells.In addition,the problems and their solutions in the process of formula simplification are analyzed.Finally,comprehensive verification is carried out based on simulation case and field case,respectively.The following results are obtained.First,when the pressure is lower than 20.1 MPa,the gas compressibility factor can be simplified to 1/pi,and the calculation formula of the elastic two-phase method can be simplified.Second,when the pressure is higher than 20.1 MPa,the original pressure should be directly used or the value of the gas compressibility factor under the condition of the maximum pressure should be adopted,or the combination of 1/pi and correction factor should be used.Third,the(normalized)pseudo-pressure method is the preferred method,and the pressure method should not be used in the case of low pressure(<13.8 MPa).In conclusion,for low-permeability and tight gas reservoirs,the flowing pressure has a linear relationship with time,but pseudo-steady flow does not occur.In this condition,the elastic two-phase method should be used with caution.Moreover,if there is pressure build-up data,it is recommended to combine the pressure drop data with the pressure build-up data(deconvolution analysis)to evaluate the reserves.
作者
孙贺东
朱松柏
姚超
赵龙飞
曹雯
曹文
杨小英
李梦勤
SUN Hedong;ZHU Songbai;YAO Chao;ZHAO Longfei;CAO Wen;CAO Wen;YANG Xiaoying;LI Mengqin(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China;PetroChina Tarim Oilfield Company,Korla,Xinjiang 841000,China;CNPC R&D Center for Ultra-Deep Complex Oil&Gas Reservoir Exploration and Development,Korla,Xinjiang 841000,China;Xinjiang Engineering Research Center for Ultra-deep Complex Reservoir Exploration and Development,Korla,Xinjiang 841000,China)
出处
《天然气工业》
北大核心
2025年第5期79-86,共8页
Natural Gas Industry
基金
中国石油天然气集团有限公司科技项目“海相碳酸盐岩油气规模增储上产与勘探开发技术研究——超深断控碳酸盐岩油藏效益开发与提高采收率研究”(编号:2023ZZ16YJ02)。
关键词
有界气藏
拟稳定流动
弹性二相法
压力法
压力平方法
拟压力法
规整化拟压力法
气体压缩系数
Bounded gas reservoir
Pseudo-steady flow
Elastic two-phase method
Pressure method
Pressure square method
Pseudopressure method
Normalized pseudo-pressure method
Gas compressibility factor
