摘要
早期预测气井产能变化规律一直都是天然气开发的技术难点之一,常用的稳定渗流分析方法误差较大,而产量递减分析及压力不稳定试井分析经典方法同样难以有效解决这一问题。为此,基于定压生产试井模型求解,改变过去简化计算指数积分函数的近似做法,精确计算气井绝对无阻流量解析解,并且以均质储层直井为参照基准,定量描述不同类型气井产能不稳定特征;结合新井产能评价的需求,研究形成了重点解决试气分析问题的实用新方法,并在四川盆地天然气开发热点区块的部分重点井进行了现场应用。研究及应用结果表明:①试井模型解析解的精确公式显著增强了对短时测试条件的适应性;②所制作的图版简要地揭示了气井不稳定产能特征与主要影响因素之间的定量关系;③当紊流效应特征参数未知时,根据定压生产试井模型分析气井无阻流量变化趋势需要进行变表皮系数迭代计算;④通过对比分析典型情况的计算结果,能够深化认识不同类型气井无阻流量的递减规律。结论认为,该新方法能够提高气井不稳定产能预测的准确性,可以广泛用于天然气勘探阶段、开发前期评价阶段、开发生产新井投产阶段的气井产能评价,有助于天然气勘探开发决策的制订。
Predicting the deliverability change laws of a gas well in the early stage is one of the technical difficulties in natural gas development.The commonly used steady seepage analysis methods have relatively large errors.And this problem cannot be solved effectively by the classical methods of production decline analysis and pressure transient well test analysis.To solve this problem,this paper did calculation based on the well testing model of constant-pressure production,changed the previous approximate method of simplifying the calculation of the exponential integral function,and accurately calculated the analytical solution of absolute open flow potential of a gas well.In addition,the deliverability instability characteristics of different types of gas wells were quantitatively described by taking vertical wells in homogeneous reservoirs as the reference benchmark.Then,combined with the deliverability evaluation needs of a new well,a new practical method focusing on solving the problems of gas formation testing analysis was researched and developed,and also applied on site at some key wells in the hot spots of natural gas development in the Sichuan Basin.And the following research results were obtained.First,the accurate formula for the analytical solution of well testing model significantly enhances the adaptability to shortterm test conditions.Second,the newly established chart briefly reveals the quantitative relationship between the unstable deliverability characteristics of a gas well and the main influencing factors.Third,if the characteristic parameter of turbulence effect is unknown,it is necessary to perform iterative calculation of the variable skin factor when the well testing model of constant-pressure production is used to analyze the change trend of the absolute open flow potential of a gas well.Fourth,by conducting comparative analysis on the calculation results of typical cases,the decline laws of the absolute open flow potential of different types of gas wells can be understood further.It is concluded that this new method is capable of improving the prediction accuracy of the unstable deliverability of gas wells.Therefore,it can be widely applied to the deliverability evaluation of gas wells in the exploration stage,the evaluation stage of early development and the commissioning stage of new development and production wells,which is conducive to the formulation of natural gas exploration and development decision.
作者
冯曦
彭先
李骞
赵晓亮
张平
潘登
FENG Xi;PENG Xian;LI Qian;ZHAO Xiaoliang;ZHANG Ping;PAN Deng(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China;College of Petroleum Engineering,China University of Petroleum,Beijing 102249,China;Engineering Technology Department,CNPC Chuanqing Drilling Engineering Co.,Ltd.,Chengdu,Sichuan 610051,China;Drilling&Production Technology Research Institute,CNPC Chuanqing Drilling Engineering Co.,Ltd.,Guanghan,Sichuan 618300,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2020年第4期59-68,共10页
Natural Gas Industry
基金
国家科技重大专项“四川盆地大型碳酸盐岩气田开发示范工程”(编号:2016ZX05052)。
关键词
气井绝对无阻流量
非稳态特征
试井模型
解析解
典型曲线图版
迭代计算
产能预测
Absolute open flow potential
Gas well
Unsteady-state characteristics
Well testing model
Analytical solution
Typical curve analysis chart
Iterative calculation
Deliverability prediction
