Causes for low CBM production of vertical wells and efficient development technology in northern Zhengzhuang Block in Qinshui Basin
-
摘要: 为了实现沁水盆地郑庄区块北部深部煤层气高效开发，通过深入分析煤储层地质条件和开发资料，并对比浅部煤层气开发数据，以含气量评价资源为基础，综合储层渗透性、地解压差，煤体结构和地应力状态等评价煤层气采出难易程度，明确郑庄区块北部煤层气井低产原因，并提出高效开发的适应技术。结果表明，郑庄北部煤层含气量整体较高，在20 m3/t以上；郑庄北部绝大部分地区裂隙发育指数均小于140，渗透率极低；绝大部分地区地解压差大于6 MPa，导致煤层气井有效解吸范围小，宏观解吸效率低；绝大部分地区煤层中碎煤比例在0.7以上，导致水力压裂裂缝较短；垂向应力大于水平应力，为大地静力场形地应力，水力压裂易形成垂直裂缝，裂缝延伸较短。极低的渗透率、相对较高的地解压差、高碎煤占比和大地静力场形地应力状态耦合导致郑庄北部煤层气开发效果较差。仿树形水平井采用人工井眼实现煤层密切割，缩短了煤层气、水渗流距离，利于实现协同降压增产，有力克服了高地解压差的不利影响；同时采用人工井眼代替压裂裂缝，解决研究区水力压裂造缝短的难题，取得了产量突破，但存在不利于排水降压和井眼易垮塌的风险，且其成本高、收效低。L形水平井密切割分段压裂技术克服了仿树形水平井不利因素。与直井相比，L形水平井成本增加2倍，但煤层气产量增加近100倍；且L形水平井与仿树形水平井产量相当，但其成本仅是后者的 40%。由此可知，L形水平井可以实现郑庄北部深部煤层气的高效开发。Abstract: In order to realize the efficient development of deep CBM in the north of Zhengzhuang block in Qinshui Basin, firstly, the geological conditions and development data of coal reservoir are deeply analyzed, and the development data of shallow CBM are compared. Secondly, based on the evaluation of gas content, the difficulty of coalbed methane recovery is evaluated by comprehensive evaluation of reservoir permeability, reservoir-desorption pressure difference, coal structure and in-situ stress state-Finally, the reasons for low production of CBM wells in the northern Zhengzhuang Block are clarified, and the adaptive technology for efficient development is put forward. The results show that the gas content in northern Zhengzhuang Block is generally higher than 20 m3/t. While the permeability is extremely low, with the fracture development index below 140. And the difference between reservoir pressure and desorption pressure(reservoir-desorption pressure difference) of CBM formation is greater than 6 MPa, resulting in small desorption range of CBM wells. In most areas, the ratio of the thickness of broken coal to that of whole coal seam is above 0.7, leading to shorter hydraulic fracturing fractures. The vertical stress, a geostatic-field-type stress, is greater than horizontal stress and the hydraulic fracturing is prone to form vertical fractures with shorter fracture extension. So the coupling of the extremely low permeability, relatively high reservoir-desorption pressure difference, high broken coal ratio and geostatic-field-type stress, all these factors result in poor production in northern Zhengzhuang Block. Artificial borehole is established by tree type horizontal well to realize high efficient stimulation of coal seam, and the coordinated depressurization is realized and the negative effects are overcome by shortening the seepage distance of CBM and water. At the same time, the artificial borehole is used instead of the relative shorter hydraulic fractures. The production of the tree type horizontal well is over 10 000 m3 per day. But the disadvantages of tree type horizontal well are risks such as unfavorable drainage and depressurization, easy hole collapse and high cost. Multi-stage hydraulic fracturing of L shaped horizontal well can overcome the disadvantages perfectly of tree type horizontal well. Compared with vertical well, the cost of L shaped horizontal well increases by 2 times while the production increases nearly by 100 times. The production of L-shaped horizontal well is as high as that of tree type horizontal well, while the cost of the L shaped horizontal well is only 40% of tree type horizontal well. In conclution, the L shaped horizontal well realize the efficient development of Northern Zhengzhuang Block.
-
-
[1] 穆福元,仲伟志,赵先良,等. 中国煤层气产业发展战略思考[J]. 天然气工业,2015,35(6):110-116. MU Fuyuan,ZHONG Weizhi,ZHAO Xianliang,et al. Strategies for the development of CBM gas industry in China[J]. Natural Gas Industry,2015,35(6):110-116.
[2] 鞠玮,姜波,秦勇,等. 多煤层条件下现今地应力特征与煤层气开发[J]. 煤炭学报,2020,45(10):3492-3500. JU Wei,JIANG Bo,QIN Yong,et al. Characteristics of present-day in-situ stress field under multi-seam conditions:Implications for coalbed methane development[J]. Journal of China Coal Society,2020,45(10):3492-3500.
[3] 刘成林,朱杰,车长波,等. 新一轮全国煤层气资源评价方法与结果[J]. 天然气工业,2009,29(11):130-132. LIU Chenglin,ZHU Jie,CHE Changbo,et al. Methodologies and results of the latest assessment of coalbed methane resources in China[J]. Natural Gas Industry,2009,29(11):130-132.
[4] 秦勇,申建. 论深部煤层气基本地质问题[J]. 石油学报,2016,37(1):125-136. QIN Yong,SHEN Jian. On the fundamental issues of deep coalbed methane geology[J]. Acta Petrolei Sinica,2016,37(1):125-136.
[5] 陈刚,李五忠. 鄂尔多斯盆地深部煤层气吸附能力的影响因素及规律[J]. 天然气工业,2011,31(10):47-49. CHEN Gang,LI Wuzhong. Influencing factors and patterns of CBM adsorption capacity in the deep Ordos Basin[J]. Natural Gas Industry,2011,31(10):47-49.
[6] 申建. 论深部煤层气成藏效应[J]. 煤炭学报,2011,36(9):1599-1600. SHEN Jian. CBM-reservoiring effect in deep strata[J]. Journal of China Coal Society,2011,36(9):1599-1600.
[7] 吴双,汤达祯,许浩,等. 深部煤层气井排采特征及产能控制因素分析[J]. 东北石油大学学报,2015,39(2):69-76. WU Shuang,TANG Dazhen,XU Hao,et al. Analysis of the characteristics of deep coalbed methane wells drainage and control factors of productivity[J]. Journal of Northeast Petroleum University,2015,39(2):69-76.
[8] 李松,汤达祯,许浩,等. 深部煤层气储层地质研究进展[J]. 地学前缘,2016,23(3):10-16. LI Song,TANG Dazhen,XU Hao,et al. Progress in geological researches on the deep coalbed methane reservoirs[J]. Earth Science Frontiers,2016,23(3):10-16.
[9] 聂志宏,巢海燕,刘莹,等. 鄂尔多斯盆地东缘深部煤层气生产特征及开发对策:以大宁-吉县区块为例[J]. 煤炭学报,2018,43(6):1738-1746. NIE Zhihong,CHAO Haiyan,LIUYing,et al. Development strategy and production characteristics of deep coalbed methane in the east Ordos Basin:Taking Daning-Jixian block for example[J]. Journal of China Coal Society,2018,43(6):1738-1746.
[10] 顾娇杨,张兵,郭明强. 临兴区块深部煤层气富集规律与勘探开发前景[J]. 煤炭学报,2016,41(1):72-79. GU Jiaoyang,ZHANG Bing,GUO Mingqiang. Deep coalbed methane enrichment rules and its exploration and development prospect in Linxing block[J]. Journal of China Coal Society,2016,41(1):72-79.
[11] 高丽军,谢英刚,潘新志,等. 临兴深部煤层气含气性及开发地质模式分析[J]. 煤炭学报,2018,43(6):1634-1640. GAO Lijun,XIE Yinggang,PAN Xinzhi,et al. Gas analysis of deep coalbed methane and its geological model for development in Linxing block[J]. Journal of China Coal Society,2018,43(6):1634-1640.
[12] 贾慧敏,胡秋嘉,祁空军,等. 高阶煤煤层气直井低产原因分析及增产措施[J]. 煤田地质与勘探,2019,47(5):104-110. JIA Huimin,HU Qiujia,QI Kongjun,et al. Reasons of low yield and stimulation measures for vertical CBM wells in high-rank coal[J]. Coal Geology & Exploration,2019,47(5):104-110.
[13] 孙斌,杨敏芳,杨青,等. 准噶尔盆地深部煤层气赋存状态分析[J]. 煤炭学报,2017,42(增刊1):195-202. SUN Bin,YANG Minfang,YANG Qing,et al. Analysis on occurrence state of deep coalbed methane in Junggar Basin[J]. Journal of China Coal Society,2017,42(Sup.1):195-202.
[14] 胡秋嘉,李梦溪,贾慧敏,等. 沁水盆地南部高煤阶煤层气水平井地质适应性探讨[J]. 煤炭学报,2019,44(4):1178-1187. HU Qiujia,LI Mengxi,JIA Huimin,et al. Discussion of the geological adaptability of coal-bed methane horizontal wells of high-rank coal formation in southern Qinshui Basin[J]. Journal of China Coal Society,2019,44(4):1178-1187.
[15] 胡秋嘉,贾慧敏,祁空军,等. 高煤阶煤层气井单相流段流压精细控制方法:以沁水盆地樊庄-郑庄区块为例[J]. 天然气工业,2018,38(9):76-81. HU Qiujia,JIA Huimin,QI Kongjun,et al. A fine control method of flowing pressure in single-phase flow section of high-rank CBM gas development wells:A case study from the Fanzhuang- Zhengzhuang Block in the Qinshui Basin[J]. Natural Gas Industry,2018,38(9):76-81.
[16] 胡奇,王生维,张晨,等. 沁南地区煤体结构对煤层气开发的影响[J]. 煤炭科学技术,2014,42(8):65-68. HU Qi,WANG Shengwei,ZHANG Chen,et al. Coal structure affected to coalbed methane development in Qinnan Region[J]. Coal Science and Technology,2014,42(8):65-68.
[17] 姚艳斌,王辉,杨延辉,等. 煤层气储层可改造性评价:以郑庄区块为例[J/OL]. 煤田地质与勘探. https://kns.cnki.net/kcms/detail/61.1155.p.20210222.1059.002.html" target="_blank"> https://kns.cnki.net/kcms/detail/61.1155.p.20210222.1059.002.html YAO Yanbin,WANG Hui,YANG Yanhui,et al. Evaluation of the hydro-fracturing potential for coalbed methane reservoir:A case study of Zhengzhuang CBM field[J/OL]. Coal Geology & Exploration. https://kns.cnki.net/kcms/detail/61.1155.p.20210222. 1059.002.html [18] 孟召平,田永东,李国富. 沁水盆地南部地应力场特征及其研究意义[J]. 煤炭学报,2010,35(6):975-981. MENG Zhaoping,TIAN Yongdong,LI Guofu. Characteristics of in-situ stress field in southern Qinshui Basin and its research significance[J]. Journal of China Coal Society,2010,35(6):975-981.
[19] 侯明勋,葛修润,王水林. 水力压裂法地应力测量中的几个问题[J]. 岩土力学,2003,24(5):840-844. HOU Mingxun,GE Xiurun,WANG Shuilin. Discussion on application of hydraulic fracturing method to geostress measurement[J]. Rock and Soil Mechanics,2003,24(5):840-844.
[20] 李峰,赵晋斌. 郑庄煤层气井体积压裂裂缝扩展特征研究[J]. 能源与环保,2020,42(8):159-163. LI Feng,ZHAO Jinbin. Study on fracture propagation characteristics of volume fracturing in Zhengzhuang CBM well[J]. China Energy and Environmental Protection,2020,42(8):159-163.
[21] 杨勇,崔树清,倪元勇,等. 煤层气仿树形水平井的探索与实践[J]. 天然气工业,2014,34(8):92-96. YANG Yong,CUI Shuqing,NI Yuanyong,et al. A new attempt of a CBM tree-like horizontal well:A pilot case of well ZS1P-5H in the Qinshui Basin[J]. Natural Gas Industry,2014,34(8):92-96.
计量
- 文章访问数: 312
- HTML全文浏览量: 24
- PDF下载量: 79
下载:
