GEOLOGICAL CHARACTERISTICS AND DISCUSSION ABOUT TECHNICAL DEVELOPMENT STRATEGIES FOR ORDOVICIAN HEAVY-OIL RESERVOIRS IN TAHE OILFIELD

Based on the analysis of the features of the karst fissuredcave typed Ordovician carbonate reservoirs in Tahe oilfield, it is considered that Ordovician reservoir is a kind of special heavy-oil reservoir and the fluids in the reservoir have strong heterogeneities both in vertical and lateral. This karst generated reservoir compartmentalization strongly results in the complexity of the reservoir property. Reservoirs that are controlled by fissures and karst caves causes heavily compartmentalization of underground fluids in different development units and the differences of well production behaviors and performances. The Ordovician reservoir may not be distributed as a whole-block, but distributed as different-sized fissure and cave units in overlapped spaces. The fluids in the reservoir is mostly common heavy oil except for extra heavy oil or ultra heavy oil in some wells with sensitivity oil temperature of about 40℃～60℃. Finally some views are presented that how to conduct further study on Ordovician reservoir, how to improve producing reserves extent and how to make optimum technical strategy etc.