摘要
沁水盆地太原组深部煤层气资源丰富,勘探开发尚未系统开展。通过解剖沁水盆地西北部古交矿区煤层气钻井、压裂、排采资料和测试数据,揭示太原组煤层厚度、含气量、储层物性等地质条件和见气压力、排采规律等开发特征,结合数值模拟提出了开发井型和井网设计。研究区太原组8号和9号主力煤层分布稳定,累计厚度约5 m,埋深在500~900 m,以低灰和低硫煤为主,生气能力强,含气量约11 m^(3)/t。煤层物性中等,含气饱和度高,临储比高,见气时间早,具有较好的开发潜力。影响煤层气开发因素包括构造运动导致地应力集中,工程改造困难;主力煤层见气压力较低,气体解吸困难;开发过程中间歇性排采,裂缝或孔喉堵塞等。基于资源丰度和见气压力对煤层气产气效果进行模拟,当储量丰度达到0.4×10^(8)m^(3)/km^(2),见气压力大于1.8 MPa时开发效果较好,模拟预测20 a累计产气量达到957×10^(4) m^(3)。研究区水平井最佳开发指标为水平段长度700 m, 8段压裂、井距300 m。当定向井与水平井距离在350 m时,布井开发效率最优。在定向井菱形井网中,短轴距离为200 m、长轴距离为300 m,开发效果最佳。综合上述煤层气开发地质条件分析,结合地质—工程一体化设计,明确了后续开发有利区和工艺选择,为研究区和类似地区煤层气高效开发提供地质支撑。
Coalbed methane(CBM) resources in the deep Taiyuan Formation of the Qinshui Basin is significant, while the development is still not fully conducted. Through systematic analysis of the drilling, fracturing, drainage, and other test data of Gujiao Mining Area in southwest Qinshui Basin, the geological characteristics like coal thickness, gas content and physical property of coal in Taiyuan Formation is revealed, as well as the production characteristics like gas emerging pressure and drainage rules. Combining numerical simulations, the favorable development areas are divided, and the well pattern and well pattern design selection are proposed. The main coal seams in the study area have stable distribution, medium thickness of 5 m, moderate burial depth between 500-900 m, low ash and sulfur, strong gas generating capacity and high gas content of 11 m^(3)/t. The coal seam has medium physical property, high gas saturation, high ratio of near reservoir and early time of gas occurrence, which has good development potential. The factors influencing the development of coalbed methane include the concentration of in-situ stress caused by tectonic movement, the difficulty of engineering reconstruction, the low gas pressure of main coal seams, the difficulty of gas desorption, the interstitial drainage during the development process, and the blockage of fractures or pore throats. Based on the resource abundance and gas pressure, the effect of coalbed methane production is simulated. When the reserve abundance reaches 0.4×10^(8) m^(3)/km^(2) and the gas pressure is greater than 1.8 MPa, the development effect is better and the predicted 20 a cumulative gas production reaches 957×10^(4) m^(3). The optimum horizontal well criteria are horizontal length of 700 m, 8 sections fracturing and 300 m well spacing. When the distance between the directional well and the horizontal well is 350 m, the development efficiency is the best. In the diamond pattern of directional wells, the short axis distance is 200 m, the long axis distance is 300 m, and the development effect is the best. The above-mentioned comprehensive analysis of the geological conditions for CBM development, combined with the integrated geology-engineering design, defines favorable areas and process options for subsequent development, providing geological support for efficient CBM development in the study area and similar areas.
作者
刘一楠
吴翔
李勇
徐立富
LIU Yinan;WU Xiang;LI Yong;XU Lifu(China United Coalbed Methane Ltd.,Beijing100011,China;College of Geosience and Surveying Engineering,China University of Mining and Technology-Beijing,Beijing100083,China)
出处
《煤炭科学技术》
CAS
CSCD
北大核心
2022年第8期125-132,共8页
Coal Science and Technology
基金
国家自然科学基金面上资助项目(41702194)。
关键词
深部煤层气
沁水盆地
井网
有利区评价
地质特征
产能优化
physical characteristics
numerical simulation
well network
favorable development area
production optimization
