特低渗透注水砂岩油藏采收率确定方法

摘要

The methods of estimating recovery factor of newly added measured reserves in existing petroleum reserves standardization of China are unsuitable for sandstone oil reservoirs of extra-low permeability with water flooding, so new empirical formula method and analogous method for estimating recovery factor of the reservoirs are studied. The key parameters influencing recovery factor are permeability, formation oil viscosity, porosity, mobility and well spacing density. Based on the requirements such as longer development time, reliable reserves and available reservoir parameters, 37 sandstone oil reservoirs of extra-low permeability were selected, and 19 recovery factor models were summarized. With consideration of high multiple regression coefficient and low standard error, 4 empirical formulae suitable for reservoir of water-flood development with vertical well were established. Comparison of calculated results from the empirical formulae and calibrated recovery factors of PetroChina recently shows that the formulae match well. It is important to choose reservoir with successful pilots and/or developed in large scale as benchmark reservoirs in the analogy estimation. Based on the principle of keeping consistent of analogous method with production performance, a practical example of Chang 8 reservoir, Triassic, FX oilfield was given to illustrate the determination of recovery factor of extra-low permeability reservoir. Empirical formula method and analogous method have their advantages and disadvantages, reserves estimators should pay great attention to the reliability of data, to application condition for empirical formulae method and to the avoidance of single reservoirs in analogous method.%针对中国现行石油储量标准新增探明储量估算采收率方法不适用于特低渗透水驱砂岩油藏的问题，研究了标定其采收率的新经验公式和类比法。经统计分析，影响采收率的关键参数为渗透率、地层原油黏度、孔隙度、流度和井网密度。根据开发时间较长、储量可靠和油藏参数齐全等条件筛选出37个特低渗样本油藏，提出19个采收率经验公式模型，考虑相关系数高和标准误差低等原则，选出适用于直井注水开发的4个采收率经验公式，经与近年可采储量标定结果检验，符合率高。类比法应选择成功开发试验区和随后大规模开发油藏作为类比的标杆油藏。依据采收率选值与生产动态一致的原则，采用类比法确定了FX油田三叠系长8特低渗透油藏标定采收率。经验公式法和类比法各有优缺点，储量评估时尤其应注意资料可靠性，经验公式法应注意适用条件，类比法中避免油藏单一性。图3表7参20