砂岩气顶油藏改建储气库库容计算方法

A METHOD FOR CALCULATING UNDERGROUND GAS STORAGE CAPACITY RECONSTRUCTED FROM SAND GAS-CAP RESERVOIR AT THE LATE WATER-DRIVING STAGE

利用华北油田水驱开发后期砂岩气顶油藏改建地下储气库,对保障京、津、冀等地区安全、平稳供气,具有非常重要的意义。虽然前期针对华北油田京58气顶油藏改建地下储气库已经开展了较深入的研究,但其库容设计存在一定局限和偏差,需要进一步深入评价。为此,依据油气藏物质平衡原理,分别提出了描述砂岩气顶油藏改建地下储气库气顶自由气库容、油层自由气库容、油层溶解气库容计算模型。通过实例求解得出气顶自由气库容量在很大程度上取决于油藏水驱过程中注入水对气顶原始含气孔隙体积的影响程度,而油层自由气库容量则取决于注气驱替效率和气驱波及体积的高低,油层剩余油溶解气量则与注入气体性质以及地层原油性质密切相关。

Building the underground gas storage on the basis of the sand gas-cap reservoir of Huabei Oilfield in the water-driving final development stage is of great significance to guarantee the safe and sustainable gas supply to Beijing, Tianjin and Hebei region. Although in-depth researches have been performed into rebuilding of the Jing 58 gas-cap reservoir, Huabei Oilfiled, to underground gas storage, its gas volume design has some limitations and deviations and deep evaluation are required. Thus, on the basis of material balance principle, the paper separately brought forward the prediction models for describing the free volume of gas-cap, oil layer and the dissolve gas volume in the oil layer of underground gas storages rebuilt from the sand gas-cap reservoir. According to the examples of prediction models, the paper pointed out that the free gas volume of gas-cap largely depends on the degree that the injecting water influences the initial gas volume of gas-cap in the reservoir water-driving process. However, the free gas volume of oil layer depends on the gas-driving sweeping volume. The remaining dissolve gas volume in the oil layer is closely-related to the properties of the injecting gas and formation oil.