摘要
低渗透储层具有应力敏感性、启动压力等极其复杂的渗流特征,西南石油大学"油气藏地质及开发工程国家重点实验室"利用长岩心实验验证了低渗透气藏中反渗吸水锁启动压力这一新的特殊渗流机理的存在。在此基础上,通过分析推导了考虑启动压力(反渗吸启动压力和常规启动压力)的低渗透气井产能公式;同时由于低渗透储层普遍具有强或极强的应力敏感性,故而进一步推导了考虑启动压力和渗透率应力敏感性同时存在的低渗透气藏产能公式。在公式推导的基础上对其进行了实例计算分析,以此评价了低渗透气井考虑特殊渗流机理的产能特征。由分析结果可发现:①随着反渗吸水锁程度的加大,气井无阻流量逐渐减小,且在形成了反渗吸水锁后,气井开井不再是一有压差就有产量,而是表现出一定的启动压力现象;②随着应力敏感性指数的增加,气井无阻流量逐渐减小;③同时考虑应力敏感和启动压力后的气井无阻流量较单纯只考虑一个因素的无阻流量要低。
The flow characteristics in low-permeability reservoirs are extremely complex due to their stress-sensitivity and starting pressure, etc. It was proven by long-core experiment at the State Key Laboratory for Oil and Gas Geology and Development Engineering, SWPU, that a special flow mechanism, starting pressure of reverse osmosis, exists in low-permeability reservoirs. Based on this discovery, a deliverability equation for low-permeability gas producers with consideration of the starting pressure (reverse osmosis and conventional starting pressures) was derived; Meanwhile, another equation with consideration of both the starting pressure and the permeability stress-sensitivity was also developed due to the existence of strong or extra-strong stress-sensitivity of permeability in low-permeability reservoirs. Calculation and analysis of practical examples have been done applying these new equations. This paper concluded these results as follows: (1) The open-flow rate of gas producers decreases with increase of water-locking degree in reverse osmosis. In addition, the producer does not produce at any small drawdown once the water-locking develops, then a starting pressure is required. (2) The open flow rate reduces when the stress sensitive index increases. (3) The open flow rate calculated with consideration of either the stress-sensitivity or the starting pressure is lower than that considering both.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2007年第11期76-78,共3页
Natural Gas Industry
关键词
低渗透油气藏
应力
启动压力
渗流
生产能力
评价
low-permeability reservoir, stress, starting pressure, flow through porous media, deliverability, appraisal
