Research On Well Pattern Adjustment Of Low Permeability Reservoir

The development efficiency of low permeability oilfield or reservoir is at a low level due to existence of starting pressure gradient. Therefore, how to improve water flood sweep efficiency has been the main concerned topic of petroleum workers, and it has been proved that infilling well pattern, shorting injector producer distance can greatly enhance oil recovery.This paper is about the technical policies of infilling well pattern in low permeability reservoir with an emphasis on rational spacing between wells, pattern of spacing and the optimization between well space and well pattern. Based on the theory of fluid flow mechanics, an express, by which the change of driving pressure gradient with well spacing under available injector-producer can be determined, was deducted. In addition, the correlation between water flood response time and well space in low permeability reservoir was detailed derived with steady replacement method. According to equilibrium principle and limit recoverable reserves of single well, an expression by which the economical well spacing can be calculated was presented. Besides, the disposition and physical properties of infill well was determined by using mathematical statistics methods. In order to select an suitable infilling pattern for the development of low permeability reservoir, well block Shu 8 in Yushulin oilfield is taken as an example for numerical simulation finally.There are several main innovations in this paper as follows:1. Provided a new method of obtaining starting pressure gradient according to water flooding response time.2. Rectified the expression by which the change of driving pressure gradient with well spacing under available injector-producer can be determined.3. Perfected the calculation formula of water displacement efficiency.4. Based on the theory of fluid flow mechanics, the critical spacing under which reasonable relationship between injector and producer could be established was present.5. The disposition and physical properties of infill well was determined with the emphases on faults controlling oil well deliverability in block-faulted oilfield by using mathematical statistics methods.The study fruits have important realistic meanings and reference value to the next-step well pattern adjustment or modification of the low permeability reservoir.