Study On The Potential & Exploitation Of Residual Oil In Lump-shaped Sand Body

In the late period of the oilfield with high water cut, it has been proved that there still exists undeveloped and high oil saturation zones within reservoir layers. The severity of inhomogeneity in these layers leads to widely scattering of the residual oil. Statistics show that 20-35%of producible residual oil is isolated from the underground due to the inhomogeneity of reservoirs, which is dotted in certain areas under the control of inner existence structures of the complex oil sand body. The key study now is how to figure out the construction structures and vadose properties of the oil sand body taking advantages of the results fine geological research. This paper will focus on it.Amid the sedimentary reservoirs of fluvial delta in Sabei oilfield develops various marginal facies tracts with complex conformation and different formation types. In the inner marginal facies tracts various sand bodies have developed there including branch-shaped deltas, transition-shaped deltas, lump-shaped deltas, lump-shaped delta sedimentary sand bodies within estuaries. And there are several other types of sands in the outer marginal facies, they are stable mat-shaped sands which developed from the main facies, mat-shaped sands which spreads with transition-shape, mat-shaped sands which dot unstably. A series of mature technological methods on description of the sand inhomogeneity properties in deltas have been found after several years of exploration and research and have helped much in making development policies of oilfieds during different steps of oilfield development. The main point of this paper will be placed on the study of lump-shaped sand which will be analyzed an researched in different aspects including sediment properties, distribution laws of oil and water, operation conditions, adaptation of well patterns making sure the distribution of lump-shaped sand reserves and the potential of residual oil. It also helps chose reasonable well spacings, well completion ways and fish out developing potential plans of the sand and attaching technics by means of perfecting the relationship between water injection and oil development and shortening well sapcings and polymer drive. All the technics are expected to deal with the super high water cut and the imbalance of reserves and development in Sabei oilfied, this is the main attack of the oilfield in terms of development, adjustment and potential seeking.