苏里格气田致密砂岩气藏效益开发含水饱和度上限

苏里格气田致密砂岩气藏含水饱和度高,投产含水率上升快,随着气井含水率增大,产量急剧降低甚至停产。在产水气井开采动态特征研究的基础上,建立气井累计采气量和采收率与含水饱和度的关系;结合单井投资及气价,确定气井收回投资所要求的最低累计采气量;并以此为依据,确定储集层含水饱和度上限。同时以气井最低累计采气量为标准,结合储集层含水饱和度及厚度,给出测井解释确定气层、气水层及含气水层的量化指标。结果表明：苏里格气田中区致密砂岩储集层的含水饱和度上限为48.2%,气井生命周期内经济最低累计采气量为1 260×10⁴ m³时,气井为效益开采。

Upper Limit of Water Saturation for Profitable Development of Tight Sandstone Gas Reservoirs in Sulige Gas Field

In the Sulige gas field, tight sandstone gas reservoirs present a high water saturation. The water cut increases rapidly after the gas wells are put into production. With the increase of water cut, the production of gas wells declines greatly or even stops. Based on the analysis of production performance of water-producing gas wells, the relationships between the water saturation and the cumulative gas production and recovery rate of the gas wells were established. Combined with the single well investment and natural gas price, the minimum cumulative gas production required to recoup the investment in a gas well was determined, and accordingly the upper limit of reservoir water saturation was determined. Furthermore, taking the minimum cumulative gas production of gas wells as the standard, and considering the reservoir water saturation and reservoir thickness, the quantitative indicators for the logging interpretation of gas layers, gas-water layers and gas-bearing water layers were determined. The results show that the upper limit of water saturation of tight sandstone reservoirs in the central part of Sulige gas field is 48.2%, and when the economic minimum cumulative gas production in the life cycle of a gas well reaches 1 260×10⁴ m³, the gas well is profitable.