摘要
煤层气主要以水力压裂的方式来提高产量,压裂过程中入井液与煤岩的接触对煤层气的生产具有较大的影响。与常规气藏不同,煤层气的产出分为解吸—扩散—渗流三个步骤,仅研究压裂液对储层渗透率的伤害不能完全反应压裂液对煤层气生产能力的伤害程度。本文利用自主研制的煤岩解吸分析实验装置,通过逐级降压测试,实时记录不同阶段下压降与解吸速率、解吸量的关系,评价了不同压裂液及添加剂对煤层气解吸扩散过程的影响。结果表明:液体进入煤基质和微割理中,阻碍了煤层气的解吸和运移;由于各种液体表面张力和润湿性的不同,对煤层气解吸伤害最小的是水源水,伤害最大的是微乳剂溶液;与干煤样解吸相比,在压裂液的作用下煤层气的解吸量主要集中在1 MPa以下,解吸速率随着压力的降低不断增大。
Hydraulic fracturing is mainly used to improve the production of coalbed methane（CBM）,which would be obviously influenced by the contact between fracturing fluid and coal in this process.Different from the conventional gas reservoir,CBM production includes three steps of desorption-diffusion-seepage.The damage degree of gas production could not be completely reflected by only investigating the effect of fracturing fluid on permeability damage.Therefore,the influence of different types of fracturing fluids and additives on desorption and diffusion of CBM was investigated by using independent development CBM desorption apparatus.The relationships between pressure drop and desorption rate as well as desorption quantity were recorded in real-time by gradual depressurization tests.The results showed that the liquid entered coal matrix and micro cleat limited the desorption and migration of CBM.Due to the difference in liquid surface tension and wettability,the lowest and highest damage degrees to CBM desorption were source water and microemulsion solution,respectively.Compared with the desorption of dry coal sample,the desorption quantity of CBM using fracturing fluids was mainly below 1MPa.The desorption rate increased with the decrease of the pressure.
出处
《中国科技论文》
CAS
北大核心
2015年第3期354-358,共5页
China Sciencepaper
基金
高等学校博士学科点专项科研基金资助项目(20125122110017)
国家科技重大专项资助项目(2011ZX05037-003)
关键词
煤层气
压裂液
逐级降压
解吸速率
解吸恢复率
coalbed methane
fracturing fluid
gradual depressurization
desorption rate
desorption recovery
