A Research On Development Performance And Residual Oil Distribution Of Dongying Formation In Northern Laoyemiao Fault-block Reservoir

Most of the oilfields are complex fault block reservoirs in the eastern part of our country. Jiangsu, Jianghan, Jidong, Liaohe, Shengli oilfields are all typical fault block reservoirs, over25%of the total number of oilfields. Now the fault block reservoirs have been put into the development, and their geological reserves and years of yeild are about a third of the national accounts. Thus fault block reservoir as crude oil reservoir important constituent occupies an important position in the oil field development.The typical characteristics of fault block oil reservoir are the geological structure, oil and water system, the fluid properties are extremely complex; there are a lot of faults and fault blocks are always small; fault-screened conditions are complex, and the reservoir heterogeneity is serious. So the cognition of the fault block oil reservoir is step by step. Because of geological, development conditions and various factors, the remaining oil distribution of fault block oil reservoir in high water cut period is more scattered. In order to enhance the recovery of north of LaoYemiao middle-deep strata high water cut fault block oilfield, groping remaining oil distribution regular rules would play an important role in the further exploring. The north of LaoYemiao middle-deep strata is complicated by fault anticline structure, fan delta front deposition sandstone; the lithology is fine, mainly fine sandstone. Reservoir physical properties are relatively good, and its average porosity is18.59%, and permeability is188.70mD, it is the middle permeability and porosity reservoir. The relations between oil and water is complicated, the strata energy is weak; it is the elastic and dissolved gas drive and middle productivity in small fault block of stratigraphic regionalization reservoir, belong to a normal temperature and pressure system. Oil property is good, underground oil viscosity is commonly1.22mPa·s-3.73mPa·s, belong to low viscosity oil reservoir. This article aims at the north of LaoYemiao middle-deep strata geological characteristics and the development present situation; on the basis of the geological researches, the main complete tasks are:through the understanding of reservoir characteristics, reservoir physical properties, seepage characteristic, the fluid properties, combined with the lab water flooding material and core analysis data, analysing various fault block formation energy, the pressure to keep degree and the oil reservoir permeability of the macro and micro group heterogeneity. After knowing the history and development of reservoir, the features and oil extraction speed, early characteristics were analyzed. Measures for increasing field are compared, oil and water wells profiles of the Lorentz curves were painted; analyzing the water injection effect; and combined with mining characteristics, water cut increasing rules and influence factors of production decline, with the purpose of providing a reference for the next step numerical simulation.The reservoir is small and single, the horizontal distribution is more scattered, oil-bearing areas are small, with a contiguous poor potato-shaped distribution; From the well evaluation of the effectiveness of reservoir performance and development capacity analysis, compared the initial to current mining situation, the study pointed out:the oilfield with a poor status of producing reserves and the formation pressure maintained low level; based on exploitation characteristics of each fault block and the development curves, the overall performance of the fault block oil and gas are of wealth inequality; the recognition of oil and water layers existed of bias in the development stage, most of the wells during the initial production of high water cut, thus a more serious impact on the development effects of the fault block; low formation-saturation pressure difference and lack of stratum energy caused short well stable time, fast production decline; from the effect of water injection analysis, the result is not satisfactory; connectivity contradictions are complex, the formation energy has not been an effective complement to the initial production, reflecting the injection patterns are imperfect, effective time of oil wells benefited is short, and water cut is rising fast; the injection patterns should be adjusted as soon as possible, and increase the point of injection wells to improve the degree of control of water flooding, reducing the rate of water cut rising; from exploitation, there are a lot of wells with low yield, damaged casing, casing deformation wells accounted for a large proportion. Oil wells production declined fast, the fault block oil production rate is low, resulting in a lower degree of recovery. Due to the inherent reservoir geological conditions, reservoir fluid properties and other natural factors, as well as the development method and level of technology and other factors, the low water flooding recovery, and increasing oil production measures got little effect. Above a number of reasons led to the development of the block is not ideal.The water drive characteristic curves, methods of production decline, empirical formula methods, the Tong’s plate method and other reservoir engineering methods were used to predict the recovery. Reasonable development and technology policy for the current problem, it is recommended that a development layer system, to improve injection recovery wells, well take the triangle well pattern, well spacing is200-250m for the best.For the numerical reservoir simulation section, we mainly use black oil simulator Eclipse reservoir simulation software. On the basis of the full history matching, based on numerical simulation studies, the residual oil distribution features have shown, and then analysis and evaluation of the various layers of exploitation of the situation were made. From a regional perspective, the residual oil saturation higher areas are mainly located in M27-25, M26-24and M109x1fault blocks; from vertical side, on each sandstone group, the distribution of residual oil between each layer, there is a big difference. Since each fault block reserves and the main oil-bearing layers and the explored levels of each block are different, the remaining potential target layers are quite diverse. According to the simulation of various programs, extracting liquid and reperforating could improve the recovery to some extent, drilling new wells in the remaining oil parts, the effect is more obvious. It is recommended that well pattern thickening and using closed wells, and completing injection and production patterns should be used in the high structural areas and the high points of the local micro-structure, and internal faults formed near the unused areas; for oil wells in poor property areas, the producing fluid structure should be adjusted, and exploit the remaining oil flexibly.