致密砂岩气藏储量难动用影响因素及开发对策

致密砂岩气藏复杂地质特性和特殊渗流机理造成相当一部分储量难以得到有效动用。以川西新场气田Js¹₂、Js³₂气藏为例，在大量室内实验及现场试验的基础上，对致密砂岩气藏渗流机理进行了深入的研究，认为水锁效应、应力敏感伤害、启动压力效应是影响储量难以动用的主要影响因素。目前的生产压差为10MPa，远大于合理的生产压差7MPa，造成较严重的应力敏感伤害；压裂过程中水锁效应则导致压裂液返排率低，压裂液滤失带启动压力高，气相渗透率低，制约了压裂开发的效果。以低伤害为核心，高效返排为手段的大型加砂压裂技术、多层压裂合层套采技术、水平井及水平井压裂技术是开发新场气田Js₂¹、Js₂³气藏难动用储量的主要技术手段。

EXPLOITATION COUNTERMEASURE OF DIFFICULTTO PRODUCE RESERVES IN TIGHT SAND GAS RESERVOIRS

Complicated geologic characteristics and special flow mechanism of tight sand gas reservoirs make a lot of reserves difficult to be developed.The exploitation of difficulttoproduce reserves is an important subject.In this paper，based on a lot experiment，the flow mechanism of tight sand gas reservoirs of Js¹₂ and Js³₂ in Xinchang gas field are studied，and the factors influencing the exploitation of difficulttoproduce reserves are analyzed.Accordingly，corresponding development strategies are put forward.As a result，water lock，stress sensitivity and threshold pressure effect are main influencing factors as to difficulttoproduce reserves.The present production pressure difference is 10MPa，much higher than reasonable pressure difference 7MPa，which results in severe stress sensitivity damage.Massive hydraulic fracturing technology with low harmful and high fracturing fluid back flow technology，multilayer fracturing technology and horizontal well technology are main exploitation strategies as to difficulttoproduce reserves in Xinchang Js₂¹、Js₂³ gas reservoir.