煤层气储层煤岩性质及其对煤层气开发的影响研究

本文以山西晋城3#煤层的煤样为研究对象,对煤岩化学成分、煤储层裂缝特征、煤岩密度、阳离子交换容量、煤岩吸水性、煤岩对液体吸着量和煤岩分散性进行研究,系统分析了煤岩性质对煤层井壁稳定和储层损害的影响。分析表明,煤层气储层煤岩煤化程度较低,裂缝发育并被粘土等矿物充填,有较强的吸水性,当钻井液滤液进入煤层后,会导致胶结物的溶解和裂缝的扩张,使煤岩强度显著下降;裂缝中粘土矿物的水化膨胀会引起储层渗透率的下降,在钻井施工当中应采用适当的技术措施,尽量避免因为煤岩化学性质而造成的不利影响。

Research on Characteristics of Rock Properties of CBM Reservoir and Their Influences on CBM Development

The paper using the No.3 seam of Jincheng in Shanxi as the object studied the chemical compositions of coal and rocks,features of cleavage and fractures,as well as the density of the coal & rocks,exchange capacity of positive ions,water adsorption property of coal and rocks,quantity of fluid adsorbed by coal and rocks and dispersion of coal and rocks.The paper made a systematic analysis on the influences of the characteristics of coal & rocks on stability of wellbore in coal seams and damages to the reservoir.The analysis showed that due to low rank of CBM reservoir,well-developed fractures which filled with minerals,like clay,etc.and strong water absorbing property,when the drilling fluid entered the coal seam,it caused the cemented materials to revolve and fractures to expand and the strength of coal rocks reduced considerably;and expansion of clay minerals in the fractures again caused reduced permeability of the reservoir.Proper technical measures should be taken in drilling operation to avoid the unfavorable influence of the chemical properties of coal and rocks.