Abstract In high-temperature, high-pressure (HTHP), water-soluble gas reservoirs, a significant amount of natural gas is dissolved in the formation water. During development, with changing reservoir pressure, the natural gas in the formation water will be released. The released natural gas will carry the formation water to form gas-liquid two-phase flow into the porous media of the gas reservoir, which results in premature water breakthrough, thus changing the law of formation water invasion. In order to determine the influence of water-soluble gas on formation water invasion, it is important to study the water-soluble gas content of water-soluble gas reservoirs. Based on experimentation and existing modeling, a prediction model was established for water-soluble gas content in HTHP water-soluble gas reservoirs, and the influence of water-soluble gas content on water invasion was studied. From the results, the following conclusions can be drawn. (a) The content of water-soluble gas increases with increasing pressure, first decreasing and then increasing with increasing temperature. (b) In addition to temperature and pressure, the factors affecting the content of water-soluble gas include the gas components and the mineralization degree of formation water. (c) The existing prediction model has the problems of large error and inconsistency with the measured value, (average error being 33.92%), especially lacking consideration of how changing carbon dioxide content in the gas composition affects the water-soluble gas content. (d) Considering the influences of temperature, pressure, gas components, and formation water mineralization on the prediction model of water-soluble gas reservoirs, the calculation results of the model are more in line with the actual circumstances of gas reservoirs, with the average error being 6.81% and the accuracy of water-soluble gas content prediction being increased five times. (e) Through case analysis, it is shown that the release of water-soluble gas has a great impact on the water breakthrough law of gas wells. Considering the water-soluble gas, the water breakthrough time of gas wells is relatively early. Results show that the water-soluble gas content prediction model for HTHP water-soluble gas reservoirs can predict the water-soluble gas content of water-soluble gas reservoirs more accurately, laying a foundation for understanding the water invasion law of water-soluble gas reservoir development and developing such a gas reservoir efficiently.

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高压高温水溶性气藏水溶性气含量预测模型

摘要 在高温高压（HTHP）水溶性气藏中，大量天然气溶解在地层水中。在开发过程中，随着储层压力的变化，地层水中的天然气会被释放出来。释放的天然气将携带地层水形成气液两相流进入气藏多孔介质，导致过早见水，从而改变地层水侵入规律。为了确定水溶性气对地层水侵入的影响，研究水溶性气藏的水溶性气含量具有重要意义。在实验和已有模型的基础上，建立了HTHP水溶性气藏水溶性气含量预测模型，研究了水溶性气体含量对水侵的影响。根据结果​​，可以得出以下结论。(a) 水溶性气体的含量随着压力的增加而增加，随着温度的升高先减少后增加。(b) 除了温度和压力外，影响水溶性气体含量的因素还包括气体成分和地层水的矿化程度。(c) 现有预测模型存在误差大、与实测值不一致的问题（平均误差为33.92%），尤其是缺乏考虑气体成分中二氧化碳含量变化对水溶性气体含量的影响。(d) 考虑温度、压力、气体成分的影响，和地层水矿化对水溶性气藏预测模型的影响，模型计算结果更符合气藏实际情况，平均误差为6.81%，水溶性含气量预测准确度较高。增加了五倍。(e) 通过案例分析表明，水溶性气的释放对气井见水规律有很大影响。考虑到水溶性气，气井见水时间相对较早。结果表明，HTHP水溶性气藏水溶性含气量预测模型能够更准确地预测水溶性气藏水溶性含气量，