Study On Policy Limit Of The Development Technology In Medium To Deep Reservoir With Low Permeability

Low permeability reservoirs are widely distributed in the world, and its resources are rich, and its exist in various oil-producing countries. With the continuous development of exploration technology, development of the objects is from high permeability reservoirs become low permeability reservoirs, from shallow reservoirs become medium to deep reservoirs. Medium to deep reservoirs with low permeability are reservoirs with low permeability, and its burial depth is over2000meters, and some even up to3000meters. According to the statistical results of the burial depth in low permeability reservoirs, among the current provened reservoirs, the proportion of reservoirs that burial depth is less than1000meters is about5.2%; the proportion of reservoirs that burial depth is from1000meters to2000meters is about43.1%, the proportion of reservoirs that burial depth is from2000meters to3000meters is about36.2%, and the proportion of reservoirs that burial depth is over3000meters is about15.5%, that is to say medium to deep reservoirs with low permeability accounted the main part of low permeability reservoirs. With the further development of the oil field, many problems during production process appear gradually. Such as the rate of production decline began faster, and the increase of the water cut become faster, and the effect of development on oil field is becoming less effective, while the the contradiction between input and output are increasing day by day. What’s more, medium to deep reservoirs with low permeability have the characteristics with deep buried depth, high formation pressure, high formation temperature and poor reservoir conditions, and it’s more difficult to develop these reservoirs. Therefore, formulating a set of reasonable development policy in connection with the characteristics of medium to deep reservoirs with low permeability is not only important for guiding the development of such reservoirs, and it can also provide practical experience for developing these reservoirs that discovered in future.Qian43oil group on Huangchang oil-field is a reservoir with14.84square kilometers proved oil area, and its reserves is2.59million tons, its average effective porosity is16.3%, its average permeability is34mD, and its burial depth is from2000meters to3300meters。It is a typical medium to deep reservoir with low permeability. Currently, the technology policy for developing medium to deep reservoirs with low permeability including the study of the type of drive on the oil-field, reasonable well spacing density, reasonable injection pressure and formation pressure, reasonable injection-production ration and so on. The paper analyzes the development conditions and evaluates the development affection of Qian43oil group on Huangchang oil-field combining relevant information of the oil-field and making full use of existing results of geological researching and dynamic data of development, and then to find the main problems and contradictions during development process on the oil-field. The paper applying reservoir engineering and combining mechanism model study the policy limit of the development technology of Qian43oil group on Huangchang oil-field from aspects including the type of drive, reasonable well spacing density, reasonable pressure, reasonable injection pressure, reasonable injection-production well ration and soon.For the type of reservoir drive, Huanchang oil field is a reservoir with poor natural energy, and its rocks are not water-sensitive or weak water-sensitive, the paper suggest the development way of injecting water to supplement formation energy for the oil field; For the study of well spacing density, the paper apply B.H.(?) formula, analysis method of reasonable production rate and so on, and then determine the suitable well spacing density of Huanchang oil field is from16to18well per square kilometers, and corresponding well spacing is from235.7to250meters; For the reasonable pressure, the paper analyse that the highest injection pressure on wellhead of the oil group can not exceed10.18MPa, and suitable fomation pressure is23.32MPa, and allowable minimum bottomhole is3.872MPa, and then the paper establish mechanism model to study reasonable formation pressure and at last summarize the suitable formation pressure is about20MPa, and corresponding level of pressure maintainion is75.7percent; At parameters of injection and production, by using method of balanced injection and production and equation of material balance, the paper suggest reasonable injection-production ration is from under1.3, and suitable ration of oil and water wells is1.75to1, what’s more, it determines suitable production rate on Huanchang oil field is from0.9percent to2.1percent, and then conbined with numericial simulation and make a conclusion that the oil group will obtain a higher degree of recovery with production rate less than1.625percent. At last, the paper prefer the reasonable deployment solution of the oil group. Practice has proved that the result of policy limits for reservoir development in the paper is reliable, applied and operational, and it is important for guiding development of similar reservoirs.