Underground And Outcrops Comparative Research About The Reservoir In Carbonate Rocks,Tarim Basin

With the deepening of Tarim basin exploration in carbonate reservoir, the importance of the fracture-cave reservoir is obvious. This reservoir often come from the Ordovician carbonate strata, has deeply buried, old, strong heterogeneity and cave complex in filling characteristics. Seriously restricted the oilfield exploration and development. This paper around this topic the characteristics of fracture-cave reservoir in carbonate. Comprehensive utilization of the wild outcrops, core and well logging, geophysical and analysis of test data, research about fracture-cave reservoirs using the comparative study on the underground reservoirs in Tahe oil field and Bachu outcrops.We researched the underground fracture-cave reservoir in Ordovician carbonate of Tahe oilfield in Tarim base.Tahe oilfield developped carbonate platform facies in the Ordovician, mainly by grainstone reservoir, limestone, baiyun ShiSha crumbs erythema shape limestone, algae (reef) limestone, dolomite, karst rock composed of six rock. The diagenesis phenomenon is complicated, weak cementation, late early compaction pressure and related to dissolve the formation, dissolve seam and karstification, mixed dolomitization in uplift period, broken and the formation of crack are conducive to the formation of good reservoir. Main diagenetic evolution characteristics of complex, the experience of subsea diagenesis, freshwater surface diagenesis environment and deeply buried diagenetic environment. There are mainly three types of reservoir spaces, inclued large cave, solution pores and crack. Fracture-cave reservoir can be divided into the hole, crack-type and fractured reservoir type. The big cave reservoir is the most important research area of fracture-cave reservoir. According to the distance form the top of cave to the surface layer of T74, three belts in vertical, including 0-60m, 60-150m and greater than 150m, and on the plane, reservoir can be divided into two layers. The fracture-cave reservoir in Ordovician carbonate of Tahe oilfield be controled by karst paleogeomorphology , palaeodrainage system and fault. In ancient landform and fault fracture zone and the fracture-cave reservoirs are more development. Through researched the fracture-cave reservoir in Ordovician carbonate of Bachu field outcrops in the Tarim basin in detail.We found that cave fillings can be divided into four types by lithology and causes,including Mechanical sediments, algal limestones (reef), chemical deposition and breccia landslide. Among them, seven kinds of cave fillings may be devoleped good reservoirs,including weakly cemented breccia, layered algae (reef) limestone, cavernous algae (reef) limestone, granular algae (reef) limestone, luminal algae (reef) limestone, layer distribution of sugar shape deposition. There are two kinds of combination patterns in fracture-cave reservoi mainly.One is devoleped be controlled by weathering profile, the other is devoleped along the fracture.The comprehensive the comparative study on cave in Ordovician carbonate in Tahe oilfield underground reservoir and Bachu field outcrop, we found there are four zones from bottom to top in fracture-cave reservoirs in Ordovician carbonate of Tarim basin, includingâ‘ Physical and biological chemical interaction with sedimentary belt,including mechanical deposition belt(â… ), algal limestones and (reef) belt (â…¡),and collapse breccia accumulation(â…¢).â‘¡Chemical deposition rocks, including deposition rocks(â…£), the empty layer between deposition (â…¤) and gravel sandstone containing calcite shell (â…¥).â‘¢the surrounding rocks belt be influenced by caves, including rupture zone(â…¦) and fracture zone(â…§).â‘£Normal surrounding rock strata(â…¨). In a reference type carbonate rocks, comprehensive vertical sequence according to surrounding rock of the core of the missing interval, combined with the characteristics of well logging curves and topographical features can predict the rock characteristics of the core of the missing interval. The found that algal limestones (reef) is a good reservoir in the cave filling of outcrops, and some evidence about algal limestones reservoirs (reef) in Ordovician carbonate reservoir in Tahe oilfield, these might mean that algal limestones (reef) is a good reservoir in Tarim basin, there are probably guidance the further exploration and find new oil reservoir. The date of rock porosity testing in Outcrop fracture-cave reservoir in Ordovician can provide good parameters for oil reserves evaluation and calculation.