基于资源性与可压性的深部煤层气“甜点”预测  

Predicting the“sweet spot”of deep coalbed methane based on resource conditions and fracability

作　　者：赵志刚 朱学申 王存武 祝彦贺 吕玉民 陈思路 齐宇 田永净 ZHAO Zhigang;ZHU Xueshen;WANG Cunwu;ZHU Yanhe;LYU Yumin;CHEN Silu;QI Yu;TIAN Yongjing(CNOOC Research Institute Co.,Ltd.,Beijing 100028,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028

出　　处：《煤田地质与勘探》2024年第8期22-31,共10页Coal Geology & Exploration

基　　金：中国海油“十四五”重大科技项目(KJGG2022-1001)。

摘　　要：【目的】我国在鄂尔多斯盆地东缘获得多个大型深部煤层气藏的勘探突破,然而如何有效地将储量转化为产量并实现高效开发尚不明确。【方法】以神府南区为例,综合应用地质、测试、压裂及生产动态资料,围绕深部煤层气藏资源性和可压性,开展地质−工程“双甜点”评价研究。【结果和结论】结果表明:(1)研究区成煤相带适宜,以三角洲沉积为主,8+9号煤层厚度大、分布稳定,热演化程度介于0.7%~1.5%,生烃条件较好;孔−裂隙系统发育,储集空间优越,为煤层气的赋存提供了储集空间;煤层顶板以封盖能力较强的泥岩为主,位于地下水滞流区,使得区内煤层气具备良好的保存条件,煤层含气性好,具有游离气与吸附气共存的特征。(2)利用井震结合的地球物理技术刻画了煤层脆性、水平主应力差和煤层裂缝的分布特征,建立了深部煤层气地质−工程“双甜点”识别指标体系,划分了3类地质−工程“甜点”区:Ⅰ类“甜点”区位于东部,Ⅱ类“甜点”区位于中西部,Ⅲ类“甜点”区位于西北部。(3)针对区内煤层埋藏深、孔渗性差、割理裂隙发育等特征,提出以“高排量大规模注入+变黏滑溜水造缝携砂+高强度加砂+全尺度裂缝支撑”为核心的体积压裂技术。压后试采评价显示Ⅰ类“甜点”区投产井上产快,峰值产量8000 m^(3)/d左右,生产稳定在7000~8000 m^(3)/d。研究成果有效指导并推动了神府区块深部煤层气勘探开发有利区优选与先导试验区方案实施,对该区深部煤层气的规模建产具有积极意义。[Objective]China has made breakthroughs in the exploration of large-scale deep coalbed methane(CBM)reservoirs along the eastern margin of the Ordos Basin.However,effectively converting the reserves of these reservoirs into production and achieving their efficient exploitation remain unclear.[Methods]Based on the geological,tests,fracturing,and production performance data,this study conducted research into the assessment of geological-engineering dual“sweet spots”of deep CBM in the southern Shenfu block by focusing on the resource conditions and fracability of deep CBM reservoirs.[Results and Conclusions]Key findings are as follows:(1)The study area hosts suitable coalforming facies zones dominated by deltaic sediments.In this block,the Nos.8 and 9 coal seams exhibit substantial thicknesses,stable distributions,and thermal maturity ranging from 0.7%to 1.5%,suggesting favorable hydrocarbon generation conditions.Furthermore,both coal seams feature well-developed pore-fracture systems,providing superior reservoir space for CBM.The roofs of both coal seams,composed primarily of mudstones with a high sealing capacity,are located in groundwater stagnation zones,creating favorable conditions for CBM preservation in the southern Shenfu block.With excellent gas-bearing properties,both coal seams show the coexistence of free gas and adsorbed gas.(2)This study characterizes the distributions of the brittleness,horizontal principal stress differences,and fractures of the coal seams using geophysical techniques that integrate logs and seismic data.Based on this,it constructs an indicator system for identifying the geological-engineering dual“sweet spots”of deep CBM,and accordingly,identifies three types of geological-engineering dual“sweet spots”in the southern Shenfu block:type I located in the eastern portion,type II in the west-central portion,and type III in the northwestern portion.(3)Considering the substantial burial depths,low porosity and permeability,and well-developed cleats and fractures of coal seams i

关 键 词：深部煤层气 成藏特征 资源条件 可压性 地质−工程“双甜点” 

分 类 号：TE122[石油与天然气工程—油气勘探]