摘要
塔里木盆地库车坳陷白垩系超深层储层埋深大于6000 m,地层流体压力系数大于1.6,温度高于130℃,网状缝—垂向缝发育、密度为3～12条/m,基质孔隙度平均为3.8％,基质渗透率平均为0.128 mD,该套超深层储层目前是天然气增储上产的核心领域.为揭示其形成机制及勘探意义,依据声发射法古应力测试、激光共聚焦显微镜、场发射扫描电镜、电子探针、激光碳氧同位素等实验分析,综合研究表明,超深层储层经历了2类典型成岩叠加效应：强构造挤压效应—强溶蚀—中等埋藏压实—中等胶结效应（克深地区）,主要发育裂缝-溶蚀孔型储层;强构造挤压 中等溶蚀 中等埋藏压实—中等胶结效应（大北地区）,主要发育裂缝-粒间孔型储层.有效储层成因机制主要为早—中期长期浅埋藏保存孔隙、中晚期膏盐岩顶蓬构造抑制垂向压实、晚期构造侧向挤压形成缝网体系、多期溶蚀作用持续增孔.有效储层主要受岩相、构造挤压和表生溶蚀作用控制,埋深超过8000m,厚度一般为80～200m.储层致密化与油气充注同期,横向叠置连片发育,为区带连片含油气、局部高丰度富集、万亿立方米天然气储量规模提供了有利条件.
The cretaceous ultra-deep reservoirs in Kuqa depression of Tarim Basin are over 6000 m deep,which have the coefficient of formation fluid pressure greater than 1.6 and the formation temperature higher than 130℃.In these ultra-deep reservoirs,nettedvertical fractures are developed at the density of 3-12 items/m,with average matrix porosity and permeability of 3.8％ and 0.128 mD,respectively.This set of ultra-deep reservoirs is presently the core area of in Kuqa depression for increasing reserve and production of natural gas.To elucidate the formation mechanism and exploration significance of ultra-deep reservoirs in Kuqa depression,experimental analysis was carried out through a combination of acoustic emission,confocal microscopy,field emission scanning electron microscopy,electron microprobe,and laser carbon and oxygen isotope techniques.Results indicated that the ultra-deep reservoirs experienced two types of typical superposition effect of diagenesis：1） strong structure extrusion-strong dissolution-moderate buried compaction-moderate cementation in the Keshen zone associated with the development of fracture-dissolved pore reservoirs;and 2） strong structure extrusion-strong dissolution-moderate dissolution-moderate buried compaction-moderate cementation in the Dabei zone associated with the development of fracture-intergranular pore reservoirs.Effective reservoirs were formed mainly through the following mechanisms：In the early-mid stage,long-term shallow burial preserved pores; in the mid-late stage,internal suspended top structure of gypsum salt rocks restrained vertical compaction; in the late stage,lateral tectonic extrusion formed the seam-net system; and multi-staged dissolution continuously increased pores.The effective reservoirs were controlled by lithofacies,tectonic extrusion and supergene dissolution,with the depth over 8 000 m and a thickness generally between 80 and 200 m.Reservoir densification and hydrocarbon filling concurrently occurred and lateral superposition continuously developed,providing favorable conditions for the formation of continuous petroliferous zones,local hydrocarbon accumulation with high abundance,and natural gas reserves on the scale of thousand-billion square meters.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2014年第6期1057-1069,共13页
Acta Petrolei Sinica
基金
国家重点基础研究发展计划(973)项目(2011CB201106)
国家重大科技专项(2008ZX05046)
中国石油天然气集团公司重大科技专项(2010E-2100)资助
