Abstract:

In the northern slope of Tazhong in Tarim Basin, Ordovician is the main hydrocarbon exploration target, and many hydrocarbon reservoirs have been discovered in this horizon. There are multiple reservoir types in this area, with complicated oil/gas/water distribution and various oil/gas characteristics. By analyzing mass wells production performances as well as testing data and discussing the distribution of fluids, faults, reservoir and high capacity or water wells, the oil/gas distribution regularity and its main controlling factors were revealed. The weathered crust unconformity developed in the top of O1y controlled the reservoir depth and reservoir thickness vertically; the horizontal inhomogeneity of the reservoir was the important reason for the oil/gas differential distribution. Height difference caused by fault had apparent impact on fluid accumulation, and structural high in the upside was more apt to oil/gas accumulation; the faults have seriously reformed the reservoirs, and the strikeslip faults as the migration pathway had obvious control action on oil/gas distribution especially, which decided the gas cutting intensity of different fossil reservoirs in the late Himalayan and the different phase reservoirs distribution. The tightlayer located in the upper part of O1y was significant for the fossil reservoirs preservation. This study will serve as an important reference to the hydrocarbon accumulation regularity research and exploratory development in the similar carbonate region.

Key words: marine carbonate, Yingshan formation of Ordovician, strikeslip fault, hydrocarbon distribution regularity, northern slope of Tazhong