Reservoir-forming Characteristics Of Paleogene And Neogene In Alar Fracture Belt

The Alar fault belt is a northwest-southeast trending fault in the Chai Southwest Central of Qaidam Basin, Qinghai Province, north of the fault belt is the Qaidam Basin’s largest Gasi Oilfield and The Yuejin2, Yuejin4, Yuedong, Yuexi and other oilfield growth on the southern.Predecessors, researched the oil and gas transport characteristics of Alar fault belt from Geochemical indicators of hydrocarbon migration power, oil and gas migration pathways et.These studies mainly focused on the analysis of hydrocarbon migration from a single geological factors, derived from insufficient understanding of systematic and comprehensive. but Lack of understanding of comprehensive and Systematic.Based on the Analysis of test data of Geology, Seismology, Drilling, Geochemistry and Rock Mechanics, combined Hydrocarbon migration driving force and Migration pathway, analyzed the characteristics of hydrocarbon migration and accumulation in Alar fault belt. Author achieved those recognize at following:(1)Generally, the Porosity sandstone and Mudstone on both sides of The Alar fault, the Parallel level’s transporting better than the vertical level’s:The Permeability ratio between mudstone parallel to the level and Vertical dimension is1.18-60.3.The Permeability ratio between Sandston parallel to the level and Vertical dimension is1.81-11.01(2)Generally, the Porosity sandstone and Mudstone on both sides of The Alar fault, the fractured sandstone and Mudstone’s transporting better than the Porous sandstone and Mudstone’s:The breakdown of fractured sandstone, mudstone’s rock sample permeability than before, Ratio is1.52-2017.57.(3)The transporting of The Alar fault depends on the Sandstone and mudstone’s evolutionary stage of rock mechanics.In the rigid and strong rupture stage and elastic-plastic compression stage, the cracks formation of Fault activity is hard to closed, its transporting performance depend on transporting of sandstone and Mudstone’s cracks. In the plastic and strong compaction stage, the cracks formation of Fault activity is easy to closed, its transporting performance depend on transporting of sandstone and Mudstone’s Pores.(4)In Alar Fault, Hydrocarbon migration resistance is very low, under Buoyancy-driven, It is easy to float to the top of the fault. It is nearly horizontal on the trend of the scope is limited to fault the top closed boundaries, Oil and gas will be enriched in the top of the fault, It will transport to the formation of the fault on both sides, and traps enrichment. When it enriched to a certain extent, Under the similar conditions in the reservoir reservoir performance, Strata near the fault at the top of the oil and gas rich.(5)Alar fault zone Paleogene-Neogene in hydrocarbon accumulation process is divided into two phases:The first stage oil and gas along the fault on both sides of rock bedding migration to N21late, Alar fault zone, north-northeast toward wear layer transport and accumulation in its footwall. Yuejin2Deep-seated, Yuedong,Yuejin4was formed in this stage. The second stage is the important period of Alar fault zone hydrocarbon accumulation:N22-Q, Oil and gas mainly through vertical fracture to fracture toward the high point of migration. Fault migration to both sides of the rock and accumulation. This stage the formation of reservoir jump oilfield, Yuejin2oilfield shallow.