高含硫气田硫磺储量计算方法的修正

MODIFICATIONS TO THE METHOD OF CALCULATING SULFUR CONTENT IN SOUR GAS FIELDS

在国内外高含硫气田开发实践过程中,普遍发现随气田开发时间的延长,产出气体中H2S含量不断上升,而产出气体中H2S含量高低与高含硫气田硫磺的储量密切相关。通过流体相平衡理论分析,认为高含硫气田H2S含量上升的原因在于原始条件下地层水中溶解有大量H2S气体,当地层压力下降时,H2S在地层水中溶解度降低导致部分H2S从地层水中逸出进入气相,使得气体中H2S含量不断上升。在此基础上,结合气—液相平衡和物质平衡理论,建立了H2S含量变化理论预测模型,对高含硫气田开发过程中H2S含量变化情况进行理论预测,进而建立了考虑气田开发过程中H2S含量变化的硫磺储量修正模型。研究结果表明,考虑H2S含量变化的修正模型所计算硫磺采出量要明显高于常规方法的计算结果,实例也表明考虑H2S含量变化的硫磺可采储量比未考虑变化规律时要高出16.3%。

According to observations on development practices of sour gas fields in the world, this study found that H2S content in the produced gas increases with the development time while it is also closely related to the sulfur in place of a gas field. Based on theory of phase balance of the fluids, this study figured out that the reason of increasing content of H2S is the dissolution of great amount of H2S from formation water under the depletion of reservoir pressure. Therefore, on the theoretical basis of gas-liquid phase balance and material balance, this study built up a forecasting model considering modifications of sulfur in place for theoretical prediction on H2S content in the produced gas. By this modified model, tests study showed that the content of the recovered sulfur was obviously higher than that calculated by the conventional methods, while some field examples demonstrated that the sulfur in place calculated by this new model was higher by 16.3%.