Main Factors Controlling Hydrocarbon Accumulation of Upper Carboniferous in M Block, Pre-Caspian Basin

The slope zone in M Block is promising zone of lithologic reservoir exploration, whereas the exploration result is low expectation duo to the insufficient knowledge of reservoir forming conditions and controlling factors. In order to solve exploration problem, by using log and oil testing data, the reservoir features, accumulation conditions, hydrocarbon reservoirs genetic types and controlling factors are studied in slope zone of Upper Carboniferous KT-.. The results show there are three types of lithological reservoirs, i.e. reservoir up-dip pinching out reservoirs, lenticular lithologic reservoirs, and fault-lithologic reservoirs. The hydrocarbon reservoirs controlling factors can be summed up as follows: primary sedimentary palaeogeomorphology and later dissolution action control reservoir distribution, unconformity and interlayer fault control hydrocarbon migration and accumulation, reservoir quality controls reservoirs scale, and the barrier of tight reservoir and antithetic faults in up-dip direction control reservoirs formation. Combining reservoir prediction and its up-dip barrier conditions, two appraisal wells were conducted and yield good results.