Research Of Methods Of Tapping Potential Oil In Thick Sandstone Layers Of Da Wangzhuang Oilfield

The development of thick sandstone formation has been the focus and key point in oilfield development, and many achievements have been made on formation correlation, barrier identification, water flooding experiment and EOR methods. A complete research technique has been developed for low-permeability formation improvement and remaining oil recovery in high-water cut stage. In this paper, studies are performed on the thick sandstone formation in Dawangzhuang oilfield. The formation characteristics are studied for different types of thick oil formation. Refined formation correlations are made based on the data of well drilling, well logging and core observation, thereby, the distribution of barriers, continuity of oil formations, distribution of sand bodies and sedimentary facies, depositional and structural characteristics are obtained. Based on the detailed formation studies, water flooding experiments are performed on cores from different depositional sandbodies, which are used together with the performance analysis to study the movement of oil and water and its according controlling factors, as well as the status of developed reserve. Numerical reservoir simulation technique is used to study the water flooding trend and remaining oil distribution. The distribution and amount of remaining oil are obtained which are used to study the method to tapping the remaining oil to improve oil recovery factor.The studies show that the remaining oil can be divided into the following types: remaining oil formed by incomplete well pattern, remaining oil formed in unswept zone, remaining oil in low-permeability zone, remaining oil formed by areal heterogeneity, etc. According development methods are designed which include drilling horizontal wells, drilling infill wells, completing well pattern, injector or producer conversion, drilling new injecting wells, deep profile controlling method, etc. Field application shows that these methods can improve the recovery factor of the remaining oil efficiently. Totally 51 wells are adjusted and obvious effect are observed: the oil production increment is 3.7×104t, and the recoverable oil reserve is increased by 14.4×104t, the natural declining ratio is decreased by 2%, and the increasing rate of water cut is reduced by 2.2%. Oil recovery factor is successful improved.