Study On The Development Mode Of Chang 2 Reservoir In Gaojiata Oilfield

Gaojiatao oil field belongs to ultra-low permeability reservoir,the main production horizon is Chang 2 reservoir.So far,only natural energy has been used for production and development.The natural energy of ultra-low permeability reservoirs in the study area is insufficient.In addition,the formation energy consumed with the reservoir development,the serious shortage of energy leads to the low production and rapid decline of the production in the study area.Obviously,the way of natural energy development can not bring beneficial economic benefits to the study area.Based on the geological characteristics and production characteristics of the study area,this paper comprehensively uses the knowledge of reservoir engineering,seepage physics and numerical simulation to research the secondary oil recovery development mode of the study area.Combining with reservoir engineering method,reservoir dynamic analysis and effect evaluation are carried out.It is clear that the reason of low production in the study area is insufficient formation energy supply,which requires the adjustment of development mode.Aiming at the adjustment of development mode,the oil displacement mechanism of water injection,gas injection and water-gas alternate development and its application effect in Ordos Basin are comprehensively analyzed,and the reasonable development mode of water injection development is optimized.According to reservoir engineering calculation,empirical method and analogy method,the technical policy boundaries of water injection development in the study area are formulated.The recovery factor of water flooding is demarcated at 13.29%.The water injection development adopts the rhombic nine-point pattern.The reasonable well pattern density is 30 wells/km~2,and the reasonable production pressure difference is 1.73MPa.On the basis of geological modeling,the history fitting is carried out,the distribution characteristics of remaining oil are analyzed,and the waterflooding development plan is designed.The mechanism of remaining oil production,the change of seepage characteristics and the recovery factor are comprehensively analyzed by using reservoir numerical simulation method,and then the waterflooding development plan is optimized.The optimum scheme shows that the recovery rate(recovery degree)reaches 12.496%after 20 years,which is higher than the natural energy development scheme by 5.34%.The increasing cumulative oil production is 24.445 million square meters.The water injection development effect is obvious and has good economic benefits.The research results can provide guidance for the improvement of water injection technology policy in the study area,contribute to the efficient development and long-term stable production of Chang 2 reservoir in the study area,and help to improve oil recovery.