摘要
针对酸压过程中形成的蚓孔区,根据压后气体渗流规律变化,基于稳定渗流理论,建立了考虑启动压力梯度、应力敏感共同影响下低渗气藏有限导流垂直酸压裂缝井产能预测模型。通过实例分析各因素对产能特征的影响。研究结果表明:气井产能随启动压力梯度和渗透率变形系数的增加下降趋势;其中考虑基于Terzaghi有效应力的应力敏感对气井产能的影响作用显著,而考虑基于岩石本体有效应力的应力敏感的影响作用小;气井产能随裂缝半长的增加而增加,且在一定裂缝长度下,裂缝导流能力存在一个最佳值,其随裂缝半长增加而增加;蚓孔区系统的蚓孔长度越长,气井产能下降幅度也越大,而蚓孔区渗透率越大,气井产能下降幅度也越小。
In view of the acid wormholing zone, based on the change of fluid flow rule after fracturing, using the steady seepage theory, with the influence of the start-up pressure gradient and stress sensitivity in the low-per- meability gas reservoirs taken into account, a gas well productivity prediction model was established for the finite conductivity vertical acid fracture wells. The influence of some factors on productivity is analyzed by using exam- pies. The result shows that the gas well productivity continues to decrease with the increasing of the start-up pres- sure gradient and the permeability deformed coefficient. The stress sensitivity based on the Terzaghig effective stress has greater effect on the gas well productivity, while the stress sensitivity based on the primary effective stress has little effect on the gas well productivity. Along with the crack length enlargement, the gas well production continues to increase, and the increasing extent is decline. Under a certain crack length, there is an optimum fracture diversion capacity, which continues to increase along with the crack length enlargement. The longer the length of acidi- zing wormhole is in the acid wormholing zone, the more the decreasing extent of the gas well productivity is. The more the permeability is in the acid wormholing zone, the lesser the decreasing extent of the gas well productivity is.
出处
《科学技术与工程》
北大核心
2013年第6期1418-1422,共5页
Science Technology and Engineering
基金
西南石油大学研究生创新基金项目(GIFSS0701)资助
关键词
低渗气藏
酸压井
蚓孔区
有效应力
产能评价
low-permeability gas reservoirs acid fracturing wellstress production evaluationacid wormholing zone effective
