Research On Comprehensive Adjustment Measures In Peripheral Low Permeability Oilfields Of Daqing

Both at home and abroad, low permeability oilfields were exploited over one hundred years ago. With the increase of energy consumption and the extension of development history, low permeability reservoirs play more important roles to reserves increase and production increase. Due to geologic conditions limit, the development of low permeability oilfields is difficult. According to development practice, water flooding is the most popular production method. The well patterns of low permeability oilfields are relatively dense with the common application of infill drilling. Moreover, based on flood development, some enhanced oil recovery methods, including MEOR, CO2 flooding, have been studied and applied.Developed blocks in Daqing can be divided into 4 types based on geologic conditions, development stages, development degrees and economic benefit. After about 20 years'development, water cut increases quickly and production declines greatly, especially in Fuyang oil reservoir. These problems are caused by some factors, such as the geologic situations of Daqing peripheral oilfields, mismatching of well array directions and fractures orientation, and unreasonable producer/injector ratio. So, development adjustment is needed.The development adjustment modes mainly include infilling and water flooding regime adjustment. In order to improve the efficiency of development adjustment, residual oil distribution is studied with the application of static and dynamic combination method and the intergration of simulation and geologic modeling.Till the end of 2007, infilling wells have been drilled in 29 blocks, and there are 6 kinds of infilling modes. For fissured reservoir, linear flooding can be used; for special low permeable one, even the injector producer distance reducing to 112m, it is difficult to have effective driving system. For SaPu layers, producer infilling between producer arrays and the center infilling in square well pattern is used; in FuYang layers, producer infilling for the well pattern with11.50 included angle, etc. Based on current technical and economical conditions, the economic results of infill in Fuyang oil reservoir with developed fractures and SaPu reservoir with medium to high water cut are better, while the potential of Fuyang oil reservoir without developed fractures is needed to be further studied. Corresponding water flooding regime adjustment modes are also applied in Daqing low permeability oilfields, for example, combine well pattern thickening with water flooding regime adjustment to well pattern with low control degree, and change inverted 9 spot water injection to 5 spot injection to well pattern with high control degree.In the peripheral oilfields, well pattern thickening and flooding regime adjustment are used to control WOR and stabilize production. 660 conversion wells and 810 infill wells are planned in 3 years hereafter to improve the development effect. These techniques will ensure the effective development of Daqing peripherial oileilds.