气井井下节流器压降模型的建立

井下节流器在天然气生产中有着重要作用,在气田尤其是苏里格气田有着大规模应用.节流器可以减少水合物生成,避免生产管线堵塞,降低井底压力激动,能有效提高气流携液能力并简化地面设备.与其他水合物预防方法相比,井下节流器成本较低,具有很好的经济效益.但同时也给生产带来一些不便,比如无法将压力计下到节流器以下,导致获得压力数据与实际井底流压相比存在节流压差,影响生产动态分析和试井解释的结果,导致解释结果有误差甚至错误,从而影响决策的正确性.以能量守恒为基础,假设气体通过节流器为等熵绝热过程,采用Peng-Robinson状态方程描述天然气节流的相平衡过程状态方程,结合其他经验公式建立井下节流器压降计算模型,并通过编程实现,化计算压差,经过实际案例验证,结果精确度较高.

Building the model for pressure drop of choke in gas-well downhole

Downhole choke plays an important role in natural gas production. It can reduce gas hydrate which will block production line. Other advantages include avoiding pressure surge and improving lifting water from downhole, etc. So this technology can Minimize the cost but bring some disadvantages as well. Such as pressure gauge can not be able reach middle depth of reservoir,so the pressure dada for production analysis and welltest is not real BHP. This paper is based on energy conservation, assuming process of gas flowing through choke is isentropic, applying PR state equation and other formula related to build the model of choke pressure drop. The program has been developed, and the result of model calculation was accurate with example.