中国海相页岩气资源潜力及未来勘探方向

Potential and future exploration direction of marine shale gas resources in China

以中国南方上奥陶统五峰组—下志留统龙马溪组页岩气为代表的海相页岩气是国内页岩气勘探开发的主战场。近年来,海相页岩气勘探开发不断面临着新的问题和挑战,开拓页岩气资源新领域和提高页岩气产量仍是重中之重。在梳理前人研究成果的基础上,分析总结国内海相层系页岩气分布特征与资源潜力,并进行有利区预测。四川盆地及其周缘五峰组—龙马溪组页岩气地质资源量和可采资源量分别为(17.50~33.19)×10^(12)m^(3)和(3.50~6.14)×10^(12)m^(3),其中深层页岩气资源占比超过50%,主要分布在川东高陡构造带和川南低陡构造带;二叠系吴家坪组页岩气地质资源量和可采资源量分别为(8.7~24.6)×10^(12)m^(3)和(1.3~3.7)×10^(12)m^(3),在川东开江—梁平、龙驹坝、建南及三星等地区具有勘探潜力;寒武系筇竹寺组页岩气地质资源量和可采资源量分别为(5.69~12.71)×10^(12)m^(3)和(0.89~1.06)×10^(12)m^(3),其有利区主要分布在川西南井研—犍为—威远—资阳、川北南江及中扬子宜昌等地区;震旦系陡山沱组、蓟县系洪水庄组和青白口系下马岭组等海相古老层系具有一定的页岩气资源潜力,是潜在的页岩气资源接续,陡山沱组页岩气有利区主要分布在湘鄂西和渝东南地区,洪水庄组页岩气有利区主要分布在河北承德—宽城一带,下马岭组页岩气有利区主要分布在河北涿州—北京房山—门头沟—昌平一带和兰旗营子一带。基于此,进一步对海相页岩气未来勘探方向提出3点建议:一是聚焦深层—超深层、常压页岩气,走向新区新层系,拓宽页岩气勘探领域;二是深化深层—超深层、完善常压及丰富新区新层系页岩气勘探理论;三是着眼深层—超深层页岩气钻完井和开采技术与配套装备改进与创新,降低常压页岩气单井钻采成本。

Marine shale gas,represented by the shale gas from Wufeng-Longmaxi formations in southern China,is the main field for shale gas exploration and development in China.In recent years,marine shale gas exploration and development have been constantly facing new problems and challenges.Expanding new fields of shale gas resources and increasing shale gas production are still top priorities.The distribution characteristics,resource potential,and favorable area prediction of shale gas in typical marine formations in China are sorted out,with the results as follows.The geological and recoverable resources of shale gas in Wufeng-Longmaxi formations in Sichuan Basin and its peripheral regions are(17.50-33.19)×10^(12)m^(3)and(3.50-6.14)×10^(12)m^(3),respectively,with deep shale gas resources accounting for over 50%,mainly distributed in the high and steep structural belt in eastern Sichuan and in the low steep structural belt in southern Sichuan.The geological and recoverable resources of shale gas in the Permian Wujiaping Formation are(8.7-24.6)×10^(12)m^(3)and(1.3-3.7)×10^(12)m^(3),respectively,with exploration potential in areas such as Kaijiang-Liangping,Longjuba,Jiannan,and Sanxing in eastern Sichuan.The geological and recoverable resources of shale gas in the Qiongzhusi Formation are(5.69-12.71)×10^(12)m^(3)and(0.89-1.06)×10^(12)m^(3),respectively,with favorable areas mainly distributed in areas such as Jingyan-Jianwei-Weiyuan-Ziyang in southwestern Sichuan,Nanjiang in northern Sichuan,and Yichang in the middle Yangtze region.The ancient marine formations such as the Doushantuo Formation,Hongshuizhuang Formation,and Xiamaling Formation have certain potential of shale gas resources,which are potential continuation of shale gas resources.The favorable areas for shale gas in the Doushantuo Formation are mainly distributed in western Hunan and Hubei and southeast Chongqing,while the favorable areas for shale gas in the Hongshuizhuang Formation are mainly distributed in the Chengde-Kuancheng area of Hebei.The favorable areas for shale gas in the Xiamaling Formation are mainly distributed in the areas of Zhuozhou in Hebei,Fangshan,Mentougou,Changping in Beijing,and Lanqi-yingzi.Based on this,three suggestions are further proposed for the future exploration direction of marine shale gas:the first is to focus on deep to ultra-deep and normal pressure shale gas,move towards new layers,and expand the field of shale gas exploration;the second is to deepen and enrich the exploration theory of deep to ultra-deep shale gas,normal pressure shale gas,and shale gas of new layer in the new area;the third is to focus on the improvement and innovation of deep to ultra-deep shale gas drilling and production technology and supporting equipment,and reduce the drilling and production costs of single wells of normal pressure shale gas.