碎软低渗煤层顶板水平井分段压裂裂缝扩展规律及机制研究

发布时间：2018-01-07 23:22

本文关键词：碎软低渗煤层顶板水平井分段压裂裂缝扩展规律及机制研究　出处：《煤炭科学研究总院》2017年博士论文　论文类型：学位论文

【摘要】：碎软低渗煤层的煤层气地面抽采,多年来一直是制约我国煤矿瓦斯灾害防治和煤层气产业化发展的技术瓶颈,也是世界性技术难题。突破碎软低渗煤层的煤层气地面抽采技术,是当今亟待研究的重大科学技术命题。本文依托"十二五"国家油气科技重大专项"两淮矿区煤层群开采条件下煤层气抽采示范工程"项目(2011ZX05064),应用煤地质学、石油天然气地质学、渗流力学、断裂力学、油气藏开发、储层模拟等理论和方法,通过理论研究、分析测试、物理模拟、数值模拟,开展了碎软低渗煤层顶板水平井分段压裂煤层气抽采模式的压裂裂缝扩展规律及机制、高效水力压裂强化增产等理论和技术工艺研究,并通过淮北矿区芦岭煤矿碎软低渗煤层顶板水平井分段压裂煤层气抽采示范工程验证,取得了以下主要研究成果和认识。(1)建立了碎软低渗煤层顶板水平井分段压裂裂缝扩展规律研究分析的、展现顶板--煤层--底板力学性质、地应力特征和水平井层位的地质—工程模型。(2)设计并进行了围压条件下多组表征碎软低渗煤层顶板水平井定向穿层压裂的物理模拟试验,揭示了在合理的水平井层位和合理的泵注排量条件下,顶板水平井压裂裂缝能够从人工顶板岩层向下穿层扩展并贯穿人工煤层,为顶板水平井分段压裂强化改造碎软低渗煤层的可行性提供了实验佐证。(3)揭示了顶板岩层水平井在向下定向射孔约束条件下的水力压裂裂缝扩展规律及机制,并建立了相应的裂缝扩展模型。在紧邻煤层的顶板岩层进行水力压裂,不仅压裂裂缝能够从高应力值的顶板岩层向下伏较低应力值的碎软低渗煤层穿层扩展和贯穿,而且在下伏碎软低渗煤层中形成的裂缝长度,由于相对脆性的顶板岩层压裂缝在横向延伸同时对煤层产生的撕扯作用,要比直接在碎软低渗煤层中进行水力压裂形成的裂缝更长。在给定的地质-储层条件和压裂工艺参数条件下前者缝长是后者缝长的6.7倍。显然,在紧邻煤层的顶板岩层进行水力压裂,大大增加了碎软低渗煤层的强化增产效果。(4)在排量为8m~3/min等模拟条件下,确定出依次压裂的最优压裂分段间距为100m,交替压裂的最优压裂分段间距为70m。(5)研究成果得到了淮北芦岭煤矿碎软低渗突出煤层顶板水平井分段压裂煤层气抽采示范工程的验证,取得了良好效果。该水平井的水平段长586m,分7段压裂,累计注入压裂液6627 m3,石英砂541m3,加砂强度77 m3/段,煤层气最高日产气量10760m3、连续3个月日产气量10000 m3以上、连续17月平均日产量高达7075 m3、已累计产气量401万方,创造了我国碎软低渗煤层的煤层气水平井水力压裂加砂量和产气量的新纪录。我国晚古生代煤田碎软低渗煤层分布广泛,高瓦斯突出矿井众多。本论文研究成果对于该类煤层的煤矿区煤层气地面抽采,尤其是突出煤层的掘进煤巷条带瓦斯地面快速预抽和区域瓦斯消突,瓦斯灾害防治,具有借鉴和指导作用,应用前景良好。
[Abstract]:Broken soft coal and low permeability coalbed gas drainage, over the years has been the technological bottleneck of gas disaster prevention and CBM industry development in China coal mine, is the world difficult problem. Drainage technology breakthrough broken soft low permeability coal seam gas surface, is a major proposition in modern science and technology to research in this paper. Relying on the "great 12th Five-Year" National Science and technology projects of oil and gas in two Huai coal mine coal mining under the condition of gas drainage demonstration project (2011ZX05064), the application of coal geology, petroleum geology, fluid mechanics, fracture mechanics, reservoir, reservoir simulation theory and method, through theoretical research, analysis test, physical simulation, numerical simulation, carried out the broken roof of horizontal wells in low permeability soft fracturing of coalbed methane fracturing production mode propagation and mechanism, hydraulic fracturing theory and technology intensive production Study on the art, and through the roof of coal seam in Luling Coal Mine of Huaibei mining area of horizontal wells in low permeability soft broken mining demonstration project to verify the pumping fracturing of coalbed gas, the main results are as follows. (1) and a broken soft and low permeability coal seam roof horizontal well fracturing crack propagation regularity analysis, show the roof - coal - the mechanical properties of floor, geological engineering model and stress characteristics of horizontal well horizon. (2) design and the confining pressure was broken characterization of physical simulation experiments of coal seam roof horizontal directional wear layer fracturing soft and low permeability, revealed in a reasonable level of well position and reasonable pump output conditions the roof cracks, horizontal well fracturing from artificial roof down wear layer and extended through artificial coal seam roof for horizontal well fracturing to strengthen the feasibility of the transformation of low permeability coal seam broken soft provides experimental evidence. (3) revealed the top Strata of horizontal wells in the downward directional perforation under the constraints of hydraulic fracture propagation law and mechanism, and establishes the corresponding model of crack propagation. The hydraulic fracturing in the roof strata adjacent to the seam, not only from the fractured roof strata of high stress values down v low stress value of broken seam expansion through the soft and low permeability, and the underlying broken crack length formed in soft seam with low permeability, the effect of roof strata tearing relatively brittle fracture in the lateral extension of the coal seam, than in the broken soft and low permeability in longer hydraulic fracturing formation in coal seam. In a given geological reservoir conditions and fracturing process parameters under the condition of the former is 6.7 times the length of slots seam length. Obviously, the hydraulic fracturing in the roof strata adjacent to the seam, greatly increasing the broken coal seam reinforcement yield soft low permeability (4). The displacement of 8m~3/min under simulated conditions, determine the optimal fracturing in fracturing segment spacing 100m, alternate optimal fracturing fracturing segment spacing is 70m. (5) of the Huaibei Luling coal mine broken soft and low permeability outburst coal seam roof horizontal well fracturing of coalbed methane production test and demonstration project, and achieved good results. 586m horizontal section of the horizontal well fracturing, divided into 7 sections, a total fracturing fluid into the 6627 m3, 541m3 of quartz sand, sand strength of 77 m3/, the highest methane gas production 10760m3, 3 consecutive months of daily production of more than 10000 m3, the 17 consecutive monthly average daily output of up to 7075 m3, has been the cumulative gas production 4 million 10 thousand square, creating a new record of China's broken CBM horizontal well hydraulic fracturing sand volume and low permeability and soft coal seam gas production in China. The late Paleozoic coal seam broken soft and low permeability are widely distributed, high gas outburst mine. This paper researches into the many The results are of reference and guidance for the surface drainage of coalbed methane in the coal seam area, especially for the tunneling of the outburst coal seam, the rapid draining of the strip and gas in the coal lane and the elimination of gas in the area, and the prevention and control of the gas disaster.

【学位授予单位】：煤炭科学研究总院
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD712.6

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