高温高压凝析气藏井筒结垢及除垢研究

塔里木油田迪那2高温高压凝析气藏共有生产井25口，其中有19口井存在井筒结垢堵塞的问题。由于迪那2气田目前主要是产凝析水，国内外尚无凝析水结垢的系统研究成果。现有的除垢剂除垢效果慢、成本高，急需开展高温高压凝析气藏井筒的结垢分布规律、垢成分、结垢原因及除垢措施研究。通过对井筒精确分段取样、室内测试、结垢原因分析及除垢措施研究，明确了井筒结垢主要集中在井筒变径的局部位置；凝析水结垢主要是生产过程中部分束缚水转变为可流动地层水，部分充填物的溶解提供了矿物离子，井筒变径位置的涡流作用引起流场、流态和相态变化，导致液体的聚集和再蒸发，从而产生结垢（盐析）；土酸酸化可高效解除井筒结垢堵塞。开展了高温高压凝析气藏井筒凝析水结垢分析研究，提出除垢措施，提供了井筒凝析水结垢的理论基础，有效恢复了气井的正常生产。

Study on wellbore scaling and descaling in high temperature and high pressure condensate gas reservoirs

There are 25 production wells in DINA-2 high temperature and high pressure condensate gas reservoir of Tarim oilfield, and the problems of scale formation and blockage in the wellbore are occured among 19 wells. The produced water mainly are condensate water in DINA-2 gas field, there has no systematic research result on scale formation of condensate water at home and abroad, and the existing descaling method by using descaling agent shows slow effect and high cost. Then the study on the distribution law of scale formation, scale composition, the cause of scale formation and descaling measure in the wellbore of high temperature and high pressure condensate gas reservoir is needed. In this paper, according to the precise subsection sampling, laboratory test, the analysis of scale formation and the study of scale removal measures, it is clear that scaling is mainly concentrated in the local location of wellbore diameter reduction. The reasons of condensate water scale formation are the transformation of part confined water into mobile formation water and the dissolution of partial backfill in the production process, which provides mineral ions. The eddy action at the diameter reducing position of wellbore causes the change of flow field, flow state and phase state, leading to the aggregation and re-evaporation of liquid, resulting in scale formation (salting out). The soil acidification can effectively remove wellbore scaling and plugging. In this paper, the study of condensate water scaling in wellbore of condensate gas reservoir is developed for the first time, the scale removal measures are proposed, and the mechanism of condensate water scaling is provided, which provides the theoretical basis for scale formation of condensate water in wellbore, and effectively restore the normal production of gas wells.