摘要
四川盆地川西北双鱼石地区雷口坡组雷三3亚段发育厚层藻白云岩储层,平面分布范围广。但其储层含气性一直存在较大争议,原因在于处于相同沉积环境的中坝地区已发现中坝气田雷三3亚段发育相同的藻白云岩储层,且储层物性好,但其气层电阻率下限值却高达1000Ω·m,远高于传统认识的气层下限值200Ω·m。为了明确雷三3亚段气层异常高电阻率原因,在综合运用薄片、全直径核磁共振和岩电实验、常规测井等资料基础上,针对中坝气田雷三3亚段储层开展实验研究。结果表明,雷三3亚段储层物性整体较好,全直径核磁共振T2谱表现为明显的双峰或三峰特征,其中,大孔隙占比约30%~60%;胶结指数m值能有效反映储层孔隙结构复杂性,其中,孤立大孔隙的增加导致胶结指数增大;当储层总孔隙度小于10%时,胶结指数随大孔隙占比增大而增大,岩心薄片上见孤立溶孔发育;当储层总孔隙度大于10%,胶结指数则随着大孔隙占比增大而逐渐减小,岩心薄片见明显微裂缝沟通溶蚀孔洞。通过岩石物理实验分析,明确了中坝地区气层高孔隙度高电阻率特征是由于孤立孔隙发育、孔隙结构复杂所导致,这为后续川西北地区雷口坡组储层及含气性认识提供指导。
The thick layer algal dolomite reservoirs developed in the 3rd member of the middle triassic leikoupo fomation(Lei-33)in the Shuangyushi area of northwestern Sichuan Basin,with a wide planar distribution.But there has been much controversy over the fluid property of the reservoir,the main reason is that the physical properties of the reservoirs in the Zhongba area which are adjacent and in the same sedimentary environment to Shuangyushi area are good,but the lower limit of the gas layer resistivity is as high as 1000Ω·m,is much higher than the traditionally recognized lower limit of the gas layer.In order to clarify the reason for the abnormal high resistivity of the gas layer,based on the comprehensive use of thin slice,full-diameter nuclear magnetic resonance,rock electrical experiment,conventional logs and other data,experimental analysis was carried out for the reservoir of Lei-33 in the Zhongba area.The results show that the physical properties of Lei-33 are relatively good.The full-diameter NMR T2 spectrum shows obvious bimodal or trimodal characteristics,of which the proportion of macropores is about 30%~60%.The cementation exponent m can effectively reflect the complexity of the pore structure of the reservoir.The increase of isolated large pores leads to an increase of the cementation exponent m.Then the total porosity of the reservoir is less than 10%,the cementation exponent m increases with the increase of the proportion of large pores,and the development of isolated dissolved pores is seen on the core slice.However when the total porosity of the reservoir is more than 10%,the cementation exponent m gradually decreases with the increase of the proportion of large pores,obvious microcracks are seen in the core thin slice which communicate the dissolved pores.Through petrophysical experiment analysis,it is clear that the high porosity and high resistivity of the gas layer in the Zhongba area are caused by the development of isolated pores and complex pore structures.
作者
田瀚
冯庆付
辛勇光
张豪
TIAN Han;FENG Qingfu;XIN Yongguang;ZHANG Hao(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Research Institute of Petroleum Exploration&Development,Beijing 100083,China;Petrochina Hangzhou Research Institute of Geology,Hangzhou,Zhejiang 310023,China)
出处
《测井技术》
CAS
2020年第5期438-442,共5页
Well Logging Technology
基金
国家科技重大专项“大型油气田及煤层气开发”(2017ZX05008-005)
中国石油天然气股份有限公司科技部重点项目“深层-超深层油气富集规律与区带目标评价”(2018A-0105)。
关键词
雷口坡组
核磁共振
岩电实验
孔隙结构
高孔隙度高电阻率储层
Leikoupo formation
nuclear magnetic resonance
rock electrical experiment
pore structure
high porosity and high resistivity reservoir
