固井水泥浆对裂缝割理发育型煤层气储层的伤害机理
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摘要
我国滇东黔西地区煤层气储层割理、裂缝发育,破裂压力低,固井水泥浆(以下简称水泥浆)容易侵入煤层气储层,造成储层伤害以及储层改造破裂压力异常升高等现象。为了揭示水泥浆伤害该类煤储层的机理,在分析煤岩的理化性能和潜在伤害方式的基础上,通过CT扫描、电镜扫描等技术手段,直观分析煤心内部污染前后裂缝、孔隙结构发育情况与水泥浆在裂缝、孔隙中的侵入、堵塞情况,进而计算得到水泥浆和裂缝在煤心中的体积占比关系,建立了水泥浆伤害煤储层的定量评价方法。研究结果表明:(1)水泥浆及其滤液在压差作用下沿煤储层的裂缝侵入储层内部,其侵入程度随裂缝、孔隙发育程度变化,裂缝、孔隙越发育,侵入程度越高;(2)侵入储层内部的水泥浆经胶结固化后,形成的水泥产物在裂缝、孔隙中致密填充,并致密覆盖煤心表面,严重堵塞煤层气流通通道,表现出固化后的水泥产物使煤心渗透率降低、煤岩抗压强度升高,使后续压裂破裂压力异常升高,影响压裂改造效果;(3)水泥浆滤液对煤岩的碱敏、速敏影响程度远小于水泥浆侵入对煤岩的伤害程度。结论认为,所建立的水泥浆污染煤储层的定量评价方法对提高煤储层固井质量、保证煤层气高效开发等都具有指导作用。
The coalbed methane(CBM) reservoirs in the areas of eastern Yunnan and western Guizhou are characterized by developed cleats and fractures and low fracturing pressures, so cementing slurry( "slurry" for short) can invade into CBM reservoir easily, resulting in reservoir damage and abnormal increase of reservoir transformation fracturing pressure. In order to reveal the damage mechanisms of slurry to this type of coal reservoirs, we analyzed the physical and chemical properties and potential damage modes of coal rocks. Then, the development situations of fractures and pores before and after the coal core samples were internally contaminated and the invasion and plugging situations of slurry in fractures and pores were analyzed intuitively by means of CT scanning and scanning electron microscope(SEM), and the percentage of slurry and fractures in coal core volume was calculated. In this way, a method to quantitatively evaluate the damage of slurry to coal reservoirs was established. And the following research results were obtained. First, under the effect of differential pressure, slurry and its filtrate invade into coal reservoirs along the fractures. The invasion degree varies with the development degree of fractures and pores. The more developed the fractures and pores, the higher the invasion degree. Second, the cement products formed after the slurry in the reservoirs gets cemented and solidified fill the fractures and pores tightly and cover the surface of coal core samples densely, so CBM flowing channels are blocked severely. Consequently, the permeability of coal core samples decreases and the compressive strength of coal rocks increase, leading to the abnormal increase of subsequent fracturing pressure and impacting the fracturing stimulation effects. Third, the effect of slurry filtrate on the alkali sensitivity and speed sensitivity of coal rocks is much less than the damage degree of slurry invasion to coal rocks. In conclusion, this newly developed quantitative evaluation method for the damage of slurry to coal reservoirs is of guiding significance to improving the cement job quality of coal reservoirs and ensuring the efficient CBM development.
The coalbed methane(CBM) reservoirs in the areas of eastern Yunnan and western Guizhou are characterized by developed cleats and fractures and low fracturing pressures, so cementing slurry( "slurry" for short) can invade into CBM reservoir easily, resulting in reservoir damage and abnormal increase of reservoir transformation fracturing pressure. In order to reveal the damage mechanisms of slurry to this type of coal reservoirs, we analyzed the physical and chemical properties and potential damage modes of coal rocks. Then, the development situations of fractures and pores before and after the coal core samples were internally contaminated and the invasion and plugging situations of slurry in fractures and pores were analyzed intuitively by means of CT scanning and scanning electron microscope(SEM), and the percentage of slurry and fractures in coal core volume was calculated. In this way, a method to quantitatively evaluate the damage of slurry to coal reservoirs was established. And the following research results were obtained. First, under the effect of differential pressure, slurry and its filtrate invade into coal reservoirs along the fractures. The invasion degree varies with the development degree of fractures and pores. The more developed the fractures and pores, the higher the invasion degree. Second, the cement products formed after the slurry in the reservoirs gets cemented and solidified fill the fractures and pores tightly and cover the surface of coal core samples densely, so CBM flowing channels are blocked severely. Consequently, the permeability of coal core samples decreases and the compressive strength of coal rocks increase, leading to the abnormal increase of subsequent fracturing pressure and impacting the fracturing stimulation effects. Third, the effect of slurry filtrate on the alkali sensitivity and speed sensitivity of coal rocks is much less than the damage degree of slurry invasion to coal rocks. In conclusion, this newly developed quantitative evaluation method for the damage of slurry to coal reservoirs is of guiding significance to improving the cement job quality of coal reservoirs and ensuring the efficient CBM development.
引文
[1]王成文,郑飞,孙晗森,王德桂,王瑞和,马洪涛.改善煤岩润湿性的强化煤层固井胶结技术[J].天然气工业, 2017, 37(7):83-88.Wang Chengwen, Zheng Fei, Sun Hansen, Wang Degui, Wang Ruihe&Ma Hongtao. Bonding-strengthening technology incoalbed cementing through wettability improvement[J]. Natural Gas Industry, 2017, 37(7):83-88.
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[3]黄文,徐宏杰,张孟江,徐大杰.贵州省织纳煤田煤层特征及煤层气资源潜力[J].天然气工业, 2013, 33(8):25-30.Huang Wen, Xu Hongjie, Zhang Mengjiang, Xu Dajie. Characteristics and CBM potentials of coal seams in the Zhina Coalfield,Guizhou[J]. Natural Gas Industry, 2013, 33(8):25-30.
[4]王瑞和,李明忠,王成文,方群.油气井注水泥顶替机理研究进展[J].天然气工业, 2013, 33(5):69-76.Wang Ruihe, Li Mingzhong, Wang Chengwen&Fang Qun.Research progress in the cementing displacement mechanism[J].Natural Gas Industry, 2013, 33(5):69-76.
[5]雷群,王红岩,赵群,刘德勋.国内外非常规油气资源勘探开发现状及建议[J].天然气工业, 2008, 28(12):7-10.Lei Qun, Wang Hongyan, Zhao Qun&Liu Dexun. Status analysis and advices on exploration and development of unconventional hydrocarbon resources[J]. Natural Gas Industry, 2008, 28(12):7-10.
[6]朱海金,王恩合,王学成,高应祥,田群山,安少辉.水泥浆防窜性能实验评价及其应用[J].天然气工业, 2013, 33(11):79-85.Zhu Haijin, Wang Enhe, Wang Xuecheng, Gao Yingxiang, Tian Qunshan&An Shaohui. Experimental evaluation of gas channeling prevention of cement slurries and its application[J]. Natural Gas Industry, 2013, 33(11):79-85.
[7]王忠勤.煤层气储层保护技术研究[J].中国煤田地质, 2001,13(3):29-30.Wang Zhongqin. Research on protective techniques of coal bed gas reservoir[J]. Coal Geology of China, 2001, 13(3):29-30.
[8]朱庆忠,左银卿,杨延辉.如何破解我国煤层气开发的技术难题——以沁水盆地南部煤层气藏为例[J].天然气工业, 2015,35(2):106-109.Zhu Qingzhong, Zuo Yinqing&Yang Yanhui. How to solve the technical problems in the CBM development:A case study of a CMB gas reservoir in the southern Qinshui Basin[J]. Natural Gas Industry, 2015, 35(2):106-109.
[9]王金,康永尚,姜杉钰,张守仁,叶建平,吴见,等.沁水盆地寿阳区块煤层气井产水差异性原因分析及有利区预测[J].天然气工业, 2016, 36(8):52-59.Wang Jin, Kang Yongshang, Jiang Shanyu, Zhang Shouren, Ye Jianping, Wu Jian, et al. Reasons for water production difference of CBM wells in Shouyang Block, Qinshui Basin, and prediction on favorable areas[J]. Natural Gas Industry, 2016, 36(8):52-59.
[10]黄质强,蒋光忠,郑双进,汪伟英,岳前升.煤层气储层保护钻井关键技术研究[J].石油天然气学报, 2010, 32(6):116-118.Huang Zhiqiang, Jiang Guangzhong, Zheng Shuangjin, Wang Weiying&Yue Qiansheng. The key drilling technique of formation protection for coal-bed methane[J]. Journal of Oil and Gas Technology, 2010, 32(6):116-118.
[11]包贵全.煤层气钻井工程中几个重点技术问题的探讨[J].探矿工程(岩土钻掘工程), 2007, 34(12):4-8.Bao Guiquan. Study on some focal technical problems of drilling engineering for coal bed methane[J]. Exploration Engineering(Rock&Soil Drilling and Tunneling), 2007, 34(12):4-8.
[12]冯明,陈力,徐承科,李春凯.中国煤层气资源与可持续发展战略[J].资源科学, 2007, 29(3):100-104.Feng Ming, Chen Li, Xu Chengke&Li Chunkai. Coal-bed methane resources and sustainable development in China[J]. Resources Science, 2007, 29(3):100-104.
[13]顾成亮.滇东—黔西地区晚二叠世煤岩及煤层气储层物性分析[J].贵州地质, 2001, 18(3):163-167.Gu Chengliang. A physical property analysis on the Upper Permian coal rocks and the coalbed gas reservoir, Eastern Yunnan and Western Guizhou[J]. Guizhou Geology, 2001, 18(3):163-167.
[14]桂宝林.滇东黔西煤层气选区及勘探目标评价[J].云南地质,2004, 23(4):410-420.Gui Baolin. The selected area and evaluation of exploration target of seam gas in East Yunnan and West Guizhou[J]. Yunnan Geology,2004, 23(4):410-420.
[15]Dharmesh T, Animesh K, Arindam S, Kuhu P, Vaibhav T, Gaurav G, et al. 200 and counting:unlocking CBM potential with highstrength,low-density cement slurry[C]//SPE/IATMI Asia Pacific Oil&Gas Conference and Exhibition, 17-19 October 2017, Jakarta,Indonesia. DOI:https://doi.org/10.2118/186976-MS.
[16]Wang C, Wang R, Zhou W&Li F. The use of a novel spacer and ultralow-density cement system to control lost circulation in coalbedmethane wells[J]. SPE Drilling&Completion, 2015, 30(1):76-85.
[17]孟召平,张吉昌, Tiedemann J.煤系岩石物理力学参数与声波速度之间的关系[J].地球物理学报, 2006, 49(5):1505-1510.Meng Zhaoping, Zhang Jichang&Tiedemann J. Relationship between physical and mechanical parameters and acoustic velocity of coal measures rocks[J]. Chinese Journal of Geophysics, 2006,49(5):1505-1510.
[2]Mohammad HSG&Shaikh SK. Coalbed methane cementing best practices--Indian case history[C]//International Oil and Gas Conference and Exhibition in China, 8-10 June 2010, Beijing, China.
[3]黄文,徐宏杰,张孟江,徐大杰.贵州省织纳煤田煤层特征及煤层气资源潜力[J].天然气工业, 2013, 33(8):25-30.Huang Wen, Xu Hongjie, Zhang Mengjiang, Xu Dajie. Characteristics and CBM potentials of coal seams in the Zhina Coalfield,Guizhou[J]. Natural Gas Industry, 2013, 33(8):25-30.
[4]王瑞和,李明忠,王成文,方群.油气井注水泥顶替机理研究进展[J].天然气工业, 2013, 33(5):69-76.Wang Ruihe, Li Mingzhong, Wang Chengwen&Fang Qun.Research progress in the cementing displacement mechanism[J].Natural Gas Industry, 2013, 33(5):69-76.
[5]雷群,王红岩,赵群,刘德勋.国内外非常规油气资源勘探开发现状及建议[J].天然气工业, 2008, 28(12):7-10.Lei Qun, Wang Hongyan, Zhao Qun&Liu Dexun. Status analysis and advices on exploration and development of unconventional hydrocarbon resources[J]. Natural Gas Industry, 2008, 28(12):7-10.
[6]朱海金,王恩合,王学成,高应祥,田群山,安少辉.水泥浆防窜性能实验评价及其应用[J].天然气工业, 2013, 33(11):79-85.Zhu Haijin, Wang Enhe, Wang Xuecheng, Gao Yingxiang, Tian Qunshan&An Shaohui. Experimental evaluation of gas channeling prevention of cement slurries and its application[J]. Natural Gas Industry, 2013, 33(11):79-85.
[7]王忠勤.煤层气储层保护技术研究[J].中国煤田地质, 2001,13(3):29-30.Wang Zhongqin. Research on protective techniques of coal bed gas reservoir[J]. Coal Geology of China, 2001, 13(3):29-30.
[8]朱庆忠,左银卿,杨延辉.如何破解我国煤层气开发的技术难题——以沁水盆地南部煤层气藏为例[J].天然气工业, 2015,35(2):106-109.Zhu Qingzhong, Zuo Yinqing&Yang Yanhui. How to solve the technical problems in the CBM development:A case study of a CMB gas reservoir in the southern Qinshui Basin[J]. Natural Gas Industry, 2015, 35(2):106-109.
[9]王金,康永尚,姜杉钰,张守仁,叶建平,吴见,等.沁水盆地寿阳区块煤层气井产水差异性原因分析及有利区预测[J].天然气工业, 2016, 36(8):52-59.Wang Jin, Kang Yongshang, Jiang Shanyu, Zhang Shouren, Ye Jianping, Wu Jian, et al. Reasons for water production difference of CBM wells in Shouyang Block, Qinshui Basin, and prediction on favorable areas[J]. Natural Gas Industry, 2016, 36(8):52-59.
[10]黄质强,蒋光忠,郑双进,汪伟英,岳前升.煤层气储层保护钻井关键技术研究[J].石油天然气学报, 2010, 32(6):116-118.Huang Zhiqiang, Jiang Guangzhong, Zheng Shuangjin, Wang Weiying&Yue Qiansheng. The key drilling technique of formation protection for coal-bed methane[J]. Journal of Oil and Gas Technology, 2010, 32(6):116-118.
[11]包贵全.煤层气钻井工程中几个重点技术问题的探讨[J].探矿工程(岩土钻掘工程), 2007, 34(12):4-8.Bao Guiquan. Study on some focal technical problems of drilling engineering for coal bed methane[J]. Exploration Engineering(Rock&Soil Drilling and Tunneling), 2007, 34(12):4-8.
[12]冯明,陈力,徐承科,李春凯.中国煤层气资源与可持续发展战略[J].资源科学, 2007, 29(3):100-104.Feng Ming, Chen Li, Xu Chengke&Li Chunkai. Coal-bed methane resources and sustainable development in China[J]. Resources Science, 2007, 29(3):100-104.
[13]顾成亮.滇东—黔西地区晚二叠世煤岩及煤层气储层物性分析[J].贵州地质, 2001, 18(3):163-167.Gu Chengliang. A physical property analysis on the Upper Permian coal rocks and the coalbed gas reservoir, Eastern Yunnan and Western Guizhou[J]. Guizhou Geology, 2001, 18(3):163-167.
[14]桂宝林.滇东黔西煤层气选区及勘探目标评价[J].云南地质,2004, 23(4):410-420.Gui Baolin. The selected area and evaluation of exploration target of seam gas in East Yunnan and West Guizhou[J]. Yunnan Geology,2004, 23(4):410-420.
[15]Dharmesh T, Animesh K, Arindam S, Kuhu P, Vaibhav T, Gaurav G, et al. 200 and counting:unlocking CBM potential with highstrength,low-density cement slurry[C]//SPE/IATMI Asia Pacific Oil&Gas Conference and Exhibition, 17-19 October 2017, Jakarta,Indonesia. DOI:https://doi.org/10.2118/186976-MS.
[16]Wang C, Wang R, Zhou W&Li F. The use of a novel spacer and ultralow-density cement system to control lost circulation in coalbedmethane wells[J]. SPE Drilling&Completion, 2015, 30(1):76-85.
[17]孟召平,张吉昌, Tiedemann J.煤系岩石物理力学参数与声波速度之间的关系[J].地球物理学报, 2006, 49(5):1505-1510.Meng Zhaoping, Zhang Jichang&Tiedemann J. Relationship between physical and mechanical parameters and acoustic velocity of coal measures rocks[J]. Chinese Journal of Geophysics, 2006,49(5):1505-1510.