普光高含H2S气田硫沉积规律及其对开发的影响

The law of sulfur deposition and its effect on production in Puguang high H2S gas reservoir

彭鑫岭 蒋光迹 彭松 彭雪葳 付德奎 陈建 李涛 徐剑明 肖盈

中国石化中原油田普光分公司，四川 达州 635000 中国石化中原油田分公司勘探开发研究院，河南 濮阳 457001 昆仑数智科技有限责任公司，北京 100000

Puguang Branch, Zhongyuan Oilfield Company, SINOPEC, Dazhou 635000, China Exploration and Development Research Institute, Zhongyuan Oilfield Company, SINOPEC, Puyang 457001, China Kunlun Digital Technology Co., Ltd., Beijing 100000, China

普光气田属于高含H2S气田，天然气中含有一定量的单质硫（简称硫，下同）。在开发过程中，随着压力和温度的持续下降，天然气中的硫将会达到过饱和，并从气相中析出。目前，普光气田地面集输流程和井筒已经出现硫沉积与堵塞，在探测和治理方面形成了较成熟的经验做法。但随着地层压力的下降，将会在储层孔喉中形成硫沉积并降低渗流能力，导致气井产能降低，甚至停喷。储层中的硫沉积治理将是气田开发工作面临的又一大难题。文中基于井下PVT取样，首先，开展天然气中硫质量浓度及PVT相态特征室内实验研究，测定了地层条件下天然气中硫初始质量浓度，建立了适用于普光高含硫气田的硫溶解度预测模型，明确了不同压力和温度条件下硫析出状态及析出量；然后，开展硫沉积对岩心渗透率伤害室内实验，理清了硫沉积对储层渗透率的伤害规律；最后，建立了硫析出和沉积预测模型，初步认清硫在井筒周围储层径向沉积规律及对气井产能的影响。研究成果将指导普光气田储层硫沉积治理工作，为高含H2S气田高效开发提供理论支持。

Puguang gas field is a high H2S gas field and contains a certain amount of elemental sulfur. The elemental sulfur in the natural gas will become supersaturated and precipitated out of the gas phase with continuous declination of pressure and temperature during development. At present in Puguang gas reservoir, sulfur deposition and blockage have occurred in the surface gathering and transportation process and in the wellbore, which formed relatively mature experience in detection and treatment of sulfur deposition. However, as the formation pressure declines, sulfur deposition will be formed in the pores of the reservoir and reduced permeability, resulting in a decrease in gas well productivity or even the suspending production. Therefore, the treatment of sulfur deposition will be another difficult problem for the development of the Puguang gas field. In this paper, firstly, based on downhole PVT sampling, the laboratory experimental research was carried out on the content of elemental sulfur in natural gas and the phase characteristics of PVT to measure the initial content of elemental sulfur in natural gas under formation condition. Also, the prediction model of elemental sulfur solubility for Puguang gas field was established, and the precipitation state and amount of elemental sulfur under different pressure and temperature were determined. Secondly, the laboratory experiment on the damage of sulfur deposition to core permeability was conducted to analyze the damage law of reservoir permeability after sulfur deposition. Finally, the prediction model of sulfur precipitation and deposition were developed, and the radial deposition rule of elemental sulfur in reservoir around wellbore and its influence on gas well productivity were preliminarily recognized. The research results will guide the management of sulfur deposition in the Puguang gas field. This is hoped to provide theoretical support for the efficient development of high H2S gas field.

10.6056/dkyqt202204004