The Study Of Karstic Reservoir Of Ordovician Carbonate Of Akekule Convex In Tarim Basin, Xingjiang

Lower ordorician are mainly production strata in Tahe oilfield. At present, important breakthroughs have been gained in the middle-upper Ordovician. Oil and gas were mainly storaged in the karstic fissure-cave. Thus, the study of karstic reservoir are very important. In this research, some conclusions are followed:l)In the Tahe oilfield, multiphase tectonic movement and pleokarst were so deeply worked on the diagenesis that the types of diagenesis are various, and the relation of those are complicated. Three diagenesis types are help to differentiate the middle Caledonian and early Hercynian karst, which are stylolite, dolomitization and dedolomitization.2)Karst identification symbols and karst reservoir of Ordovician in bores, logging, well logging and FMI have been established. Karst reservoir have been identified and evaluated in the Tahe oilfield.3)On the basis of the geochemistry methods of cathodoluminescencean, strontium isotope, carbon and oxygen isotope, trace element, inclusion, etc, pleokarst mechanism have been deeply studied. Pleokarst had been brought about in the meteoric water of earths surface , and mainly in the early hercynian movement.4)Through making maps of cave section correlation in the pleokast topography of the early Hercynian movement, three karstic circle are recognized in Tahe oilfield, and each circle were produced one cave layer, the top cave are earlier than the down caves. Karst cycle II could reconstructed the middle and upper ordorician, and the cave preservation of the karst cycle IK III are better than the cave of the karst cycle I.5)The genetic forecast mode of karst reservoir in the Tahe oilfield are founded on the basis of the research of pleokarst topography, pleodrainage system and karst cycle.6)Through the study of the karst reservoir distribution on the plane, pleokarst topography, pleodrainage system and the preservation of cave, the distribution evaluation of karstreservoir in the Tahe oilfield has been done. The most developed areas of karst reservoir are 3, 4 and 6 area.