鄂尔多斯盆地DJ区块深部煤储层地质-工程甜点测井评价技术

Logging-based evaluation for geological-engineering sweet spots in deep coal reservoirs of the DJ block， Ordos Basin

王舵 刘之的 王成旺 刘天定 陈高杰 郝晋美 孙博文

Duo WANG Zhidi LIU Chengwang WANG Tianding LIU Gaojie CHEN Jinmei HAO Bowen SUN

深部煤层气由于储层非均质性强、应力大、压力高和可改造性差，因此，其规模化开发要求对甜点开展精细评价。基于层次分析法（AHP法）提出了深部煤储层地质-工程甜点的12项评价指标，建立了测井评价模型，利用该模型对鄂尔多斯盆地DJ区块20余口井的深部煤储层甜点进行了评价。研究结果表明：①煤储层地质-工程甜点主控因素与产能施工压力比（）存在良好的相关性。DJ区块深部煤储层的上部甜点类别普遍优于中、下部，上部主要为Ⅰ类甜点，中部为Ⅲ类甜点，下部为Ⅱ类甜点。②含气量和脆性指数分别是储层及工程品质的主控因素。③煤储层顶、底板发育较厚的灰岩和泥岩，煤储层与灰岩和泥岩的力学特性差异较大，能有效封隔压裂缝在煤储层中扩展。压裂工况和试气结果表明所构建的地质-工程甜点测井评价方法应用效果良好，可用于深部煤储层压裂射孔选段和测井优选评价。

The deep coal seams rich in coalbed methane （CBM） resources feature strong heterogeneity， high stress， high pressure， and challenging stimulation， rendering the accurate sweet spot evaluation crucial to the large-scale production of deep CBM. This study focuses on the logging-based evaluation of integrated geological-engineering sweet spots in deep coal seams， establishing an evaluation model with 12 evaluation indices using the analytic hierarchy process （） method. Employing this model， we carry out sweet spot assessment of deep coal seams in over 20 wells in the DJ block. The results indicate that the major determinants of the geological-engineering sweet spots are strongly correlated with the ratio of a CBM well’s daily gas production to its construction pressure in the proppant transport stage （）. The upper part of deep coal seams in the DJ block generally exhibits superior sweet spots compared to its middle and lower counterparts. Specifically， the upper， middle-lower， and lower parts predominantly exhibit Class Ⅰ， Ⅲ， and Ⅱ sweet spots， respectively. Gas content and brittleness index are identified as the primary factors controlling high-quality reservoirs and engineering sweet spots. The coal seams’ roofs and floors consist of thick limestones and mudstones， which exhibit significantly different mechanical properties from the coal seams and thus effectively block the propagation of induced fractures across the coal seams. The fracturing conditions and production test results indicate promising outcomes of the logging-based evaluation model. Therefore， this model can be applied to the logging-based selection and evaluation of the optimal perforation sections for the hydraulic fracturing of deep coal seams.

10.11743/ogg20240620