中国南海东部强边底水驱气藏储量计算新方法

计算气藏动态储量最常用的方法是压降法，该方法不需要知道水侵量的大小，仅依靠生产动态数据，绘制累计产量与视地层压力的关系曲线，就可以计算动态储量。但压降法需要较多的测试地层压力数据且要求测试数据准确可靠，对南海东部普遍存在的强边底水气藏采用常规的压降法计算出的动态储量往往比实际值大，甚至高于静态地质储量，因为水侵往往比人们观测到时发生得更早，要准确计算此类气藏的动态储量需要考虑水体的影响。为此，提出了一种适用于强水驱气藏的储量计算方法，该方法首先将多井系统等价为１口井生产的情形，引入水驱气藏物质平衡方程和测试的地层静压为约束条件，建立产量、流压、测试地层压力目标函数，拟合生产动态数据，获得动态储量，并能求出水侵量。用南海东部PY30 1气田某层位计算实例验证了该方法，结果表明，该方法能更好地用于水体活跃程度高的气藏，动态储量计算结果可靠度、可信度均高。

A new method of calculating the reserves of gas reservoirs strongly driven by edge and bottom water in the eastern South China Sea

The pressure drop method is the most common method for calculating the dynamic reserves of a gas reservoir. With the water influx value unnecessarily known, this method can calculate dynamic reserves by plotting the relation curve of the cumulative production vs. reservoir pressure based on the production data. However, this method requires a large amount of accurate and reliable strata pressure data. The dynamic reserves calculated by this method are usually higher than the actual values of the gas reservoirs strongly driven by edge and bottom water in the eastern South China Sea, even higher than the static geological reserves. The water influx usually occurs earlier than the monitored results, thus the influence of the water body should be considered in the calculation of the dynamic reserves of such this type of gas reservoirs. Therefore, a new method is proposed herein in this case. First it equates the production of the multi well system with that of one well and introduces the material balance equation of water drive gas reservoirs and tested formation static pressure as the constraint conditions, then establishes the objective function of output, flowing pressure and tested formation pressure, fits the dynamic production data, and finally obtains the dynamic reserves and the volume of water influx. Through the calculation of one sequence layer in the PY30 1 field in the eastern South China Sea, this new method is validated with highly reliable calculation results. This new method is better used for the reserve estimation of such gas reservoirs with a high degree of active water body.