高含CO气井产能计算新方法

A new method of productivity prediction for high CO-content gas wells

严谨 刘传喜

Yan Jin Liu Chuanxi

松南火山岩气藏高含CO,这种气体的存在对天然气的高压物性产生很大影响,使得气井产能预测与实际相差较大。在高含CO气体高压物性分析(PVT)实验的基础上,研究了温度、压力和CO含量对天然气高压物性参数的影响规律,建立了不同CO含量下天然气粘度和偏差因子与压力的相关关系,并结合气体渗流理论建立了考虑高含CO天然气高压物性变化的产能预测新模型。实例计算表明:①气井产能随着CO含量的增高而降低;②当CO含量大于20%时,气井产能评价必须考虑值(天然气粘度与偏差因子的乘积)变化的影响;③开发中后期可以忽略CO含量对气井产能的影响。新的产能计算方法能反映CO含量对产能计算的影响,精确度更高,对于高含CO天然气田的产能评价和生产制度的制定具有重要的指导意义。

Productivity of gas wells in Songnan volcanic gas reservoir is difficult to predict as high CO content has great influences on PVT of natural gas,resulting in large difference between the measured and predicted productivity.Based on laboratory experiments,this paper studied the effects of temperature,pressure and CO content on PVT of gas with high CO content and established the relational expressions of gas viscosity and Z-facto to pressure for gas with different CO contents.A new prediction model considering PVT variations of gas with high CO content was built based on gas percolation theory.The case study results indicate that the productivity reduces with the CO content increasing;the effect of factor changes on productivity prediction should be considered when CO content is above 20%;and the impacts of CO content on productivity lowers to a level that can be neglect in late production period.The new method is accurate and practical for the high CO-content gas reservoirs.

10.11743/ogg20110518