煤层气储层压裂现状及展望

Status and prospects of coalbed methane reservoir fracturing

为了深入研究煤层压裂,提高煤层压裂效果,总结分析了煤层压裂液、压裂支撑剂、压裂裂缝数值模拟、裂缝监测、煤层压裂设计及施工工艺的现状。通过对比分析得出,活性水与石英砂组合是浅层煤层气压裂的主要组合方式,但随着深度的增加,储层地质复杂性的增强,该组合压裂后的效果逐渐变差;传统的二维和拟三维裂缝模拟方法在煤层应用中具有局限性,需要根据煤储层地质特征对裂缝模拟方法进行优化;多种裂缝监测方法在煤层应用中的结果表明,煤储层压裂后主要呈现出贯穿煤层的垂直裂缝、垂直裂缝与水平裂缝组合的复杂裂缝和非对称网络裂缝3种形态。我国已探索出以活性水直井压裂为主,水力波及压裂和间接压裂等多种压裂工艺为辅的压裂工艺技术。最后对煤层压裂提出了展望,即在低成本和高效环保的前提下,从增加煤层改造体积和增大解吸面积的压裂机理出发,结合煤岩工程地质特征,优选压裂材料及配套压裂技术,为煤层气的合理高效开发提供理论指导。

In order to deeply study the seam fracturing and to improve the fracturing effect of the seam,the paper summarized and analyzed the seam fracturing fluid,fracturing proppant,numerical simulation of the fractured cracks,crack monitoring and measuring,seam fracturing design and construction technique status.The comparison analysis showed that the activated water combined with the quartz sand would be the major combination mode of the coalbed methane fracturing in the shallow depth seam.But with the depth increased and the geological complexity of the reservoir enhanced,the after fracturing effect of the major combination mode would be steadily poor.The application of the conventional two dimension and the pseudo-three-dimension crack simulation method would be limited to the seam and the optimization should be conducted on the crack simulation method according to the geological features of the coal reservoir.The results of the multi crack monitoring method to the seam showed that after the coal reservoir fractured,there would be three shape complicated crack and asymmetry network cracks combined with the through seam vertical cracks,vertical cracks and horizontal cracks.Mainly the activated water vertical fracturing,the hydraulic wave and fracturing and indirect fracturing and other multi fracturing techniques as the secondary fracturing technique and technology were discovered in China.Finally,an outlook on the seam fracturing was provided,thus on the premise of the low cost and high efficient environment protection,from a view of the fracturing mechanism to increase the seam reconstruction volume and to increase the desorption area,in combination with the coal and rock engineering geological features,the optimum fracturing material and the matched fracturing technology would provide the theoretical guide to the rational high efficient development of the coalbed methane.