高阶煤支撑剂嵌入模型  

Proppant Embedment Model of High Rank Coal

作　　者：张遂安[1,2] 曹立虎 谭扬军[1,2] 刘岩 王伟[1,2] 黄兆鑫[1,2] 

机构地区：[1]中国石油大学(北京)煤层气研究中心 [2]气体能源开发与利用教育部工程研究中心,北京102249

出　　处：《科技导报》2014年第14期54-58,共5页Science & Technology Review

基　　金：国家科技重大专项(2011ZX05034-003;2011ZX05061;2011ZX05062;2011ZX05063)

摘　　要：支撑剂嵌入煤层会损害压裂支撑裂缝导流能力。目前关于煤岩支撑剂嵌入的研究主要为实验研究,缺乏相应的理论数值计算模型。为此,对沁水盆地端氏、曲堤和候村高阶煤层的支撑剂进行嵌入实验,分析了闭合压力和煤岩坚固性系数对支撑剂嵌入的影响;根据Langmuir定律,推导出二维多层支撑剂嵌入煤岩的缝宽模型和压嵌模型,利用实验数据对模型进行了验证。结果表明:支撑剂嵌入煤岩时,存在临界嵌入压力,煤岩坚固性系数越小,临界嵌入压力越小,支撑剂越易嵌入煤岩;在闭合压力小于30 MPa时,支撑剂嵌入煤岩程度小于支撑剂粒径的1/2时,模型计算结果与实验测试结果相似程度较高,推导出的缝宽模型和压嵌模型能有效指导沁水盆地高阶煤层的水力压裂施工设计。The successful development of coalbed methane in China is essential to national energy security, coal mining safety and the environment. Creating high conductivity fracture within coal matrix using hydrofracture has been regarded as one of the most effective technologies for coalbed methane development. As a complicated procedure, however, the ability to create fractures with high conductivity is significantly influenced by flowing back, smashing and embedding of the proppant, which can be well represented by the operations in the study area Qinshui basin. The proppant is easily embedded into the surface around the fracture during hydrofracture in highly matured soft coal in Qinshui basin. Hence, conductivity of the generated fracture is dramatically reduced as a result of narrow fracture with embedded proppant. Currently, studies on proppant embedding are mainly conducted in physical experiments, lacking the corresponding numerical models. To analyze the influence of closure pressure and Protodyakonov coefficient on proppant embedding in a numerical method, width formulas and embedded pressure formulas for coal were deduced based on Langmuir law. Experiments for examining the model have been conducted as well. The results show that there is a critical pressure during insertion of the proppant into the coal surface. The smaller the protodyakonov coefficient is, the lower the critical pressure becomes, and the easier the insertion of the proppant is. When the closure pressure was lower than 30 MPa, and only half or even less of the proppant was inserted into the coal, relatively high similarity was obtained between the calculated results from the numerical model and the experimental results. Thereby, the deduced width formulas and embedded pressure formulas are valuable in the hydrofracture design for the high rank coal in Qinshui Basin.

关 键 词：高阶煤 坚固性系数 支撑剂嵌入 缝宽模型 压嵌模型 

分 类 号：TE377[石油与天然气工程—油气田开发工程]