苏东地区气藏水锁机理分析及水锁判识

苏东地区气藏水锁机理分析及水锁判识

陈存良1，2

，梁

艳3，刘向前3，南学龙3，顾

聪3

（1.西安石油大学，

陕西西安710065；

2.中国石油长庆油田分公司气田开发事业部，

陕西西安710018；3.中国石油长庆油田分公司第五采气厂，陕西西安710018）

摘要：苏东地区属于典型的低渗致密气藏，气田开发面临的突出问题是积液气井的比例不断上升，高液气比条件下水锁伤害更为严重，造成大量的气井产量明显下降甚至停产，严重影响了苏东地区气藏的有效开发。本文在充分调研前人研究的基础之上，深入分析苏东地区水锁产生的机理及模式，以储层特征和采气曲线形态为出发点研究总结气井水锁判识特征，为苏东地区提高气藏采收率，制定最优化的水锁预防及解除措施提供最科学的基础依据，为相似区块水锁判识及相应的水锁防治方案提供经验借鉴。研究结果表明：苏东地区气井水锁的主要原因有3个；根据储层特征及改造方式的不同，苏东气井水锁可总结为两种不同的水锁伤害模式，“上古生界储层水锁模式”：以近井筒水相圈闭和储层远端水锁为主要形式，两者之间存在一个水锁堵塞区，“下古生界储层水锁模式”：以近井筒水相圈闭与水锁为主要形式，水相圈闭和水锁区域没有明显界限。分析总结苏东地区近1000口的生产曲线数据，

梳理出4种类型的水锁判识特征曲线，提出储层水锁难易程度的判识和气井水锁效应判识（生产曲线特征）密切结合，才能保证气井水锁不漏判，才能为制定最优化的水锁预防及解除措施提供最科学的依据。

关键词：苏东地区；致密气藏；水相圈闭；水锁机理；水锁判识；采气曲线特征中图分类号：TE311

文献标识码：A

文章编号：1673-5285（2019）05-0054-07

DOI:10.3969/j.issn.1673-5285.2019.05.010

Mechanism analysis of the water blocking of gas reservoirs

and its identification in eastern Sulige gasfield

CHEN Cunliang 1，2

，LIANG Yan 3，LIU Xiangqian 3，NAN Xuelong 3，GU Cong 3

（1.Xi'an Shiyou University ，Xi'an Shanxi 710065，China ；2.Gas Field Development Division of PetroChina Changqing Oilfield Company ，Xi'an Shanxi 710018，China ；3.Gas Production

Plant 5of PetroChina Changqing Oilfield Company ，Xi'an Shanxi 710018，China ）

Abstract:There are typical low permeability tight gas reservoirs in the eastern Sulige gas -field,Ordos basin.The outstanding problems of gasfield development is that the proportion of gas wells with wellbore fluid is rising continuously.Under the condition of high liquid gas ra -tio,water blocking damage is more serious,resulting in a large number of gas production de -creased or even discontinued.It has seriously affected the effective development of gas reser -voirs in the eastern Sulige gasfield,Ordos basin.To provide the most scientific basis for im -proving the recovery efficiency of gas reservoirs and optimizing water blocking prevention and removal measures in the study area,the water blocking mechanism and models were an -

*

收稿日期：2019-04-07

石油化工应用

PETROCHEMICAL INDUSTRY APPLICATION

第38卷第5期2019年5月Vol.38No.5May.2019

alyzed in detail based on the research of previous studies,the identification characteristics of water lock in gas wells are summarized based on reservoir characteristics and gas production curve.It provides experience reference for similar block water lock identification and corre-sponding water blocking prevention and control program.The results show that there are three main reasons of gas well water blocking in the study area.According to the reservoir charac-teristics and the transformation of different types,water blocking can be summarized as two different kinds of water blocking damage model."water locking model of Upper Paleozoic reservoir"mainly shows the water phase trapping in the near wellbore area and the water blocking of the distal reservoir,with the tight water blocking zone between them."The water locking model of Lower Paleozoic reservoir"mainly shows the water phase trapping near the wellbore area and water locking,and there is no obvious boundary between them.By analyz-ing and summarizing the production curve data of nearly1000outlets in the eastern Sulige gasfield,four types of water blocking identification characteristic curves are sorted out.It pointed out that probability prediction of water blocking in reservoir and water blocking i-dentification should be closely combined to ensure the water blocking without leakage judg-ment,so as to provide the most scientific basis for the development of optimal water blocking prevention and relief measures.

Key words：eastern Sulige gasfield；tight gas reservoirs；water phase trapping；water blocking mechanism；water blocking identification；characteristics of gas production curve

水锁损害广泛存在于低渗透致密砂岩油气藏，是低渗透致密砂岩油气藏的主要损害类型之一，严重地影响着油气藏的勘探开发效果。尽管目前关于水锁伤害的室内评价尚无统一的评价标准和规范流程，针对具体作用过程，不同学者采取了不同实验方法进行评价，但水锁效应对渗透率造成伤害已经形成共识[1-4]，研究表明渗透率越小的岩心，水锁伤害越严重，低渗致密储层水锁伤害率平均可达到76.49%，水锁伤害对产能的影响显著，水锁发生后使气体的产能下降的幅度超过了60%[4]。目前关于水锁效应（特别是针对低渗致密气藏的水锁效应）有大量公开文献的发表，研究内容主要集中在水锁效应的影响因素、水锁伤害程度评价及各种化学药剂的解水锁效果分析等方面[1-8]，对于水锁效应的判识方面鲜有提及，且常规研究方法需使用大量岩心进行测试，时间较长，无法快速应用于生产中，如何快速、准确地诊断与预测气藏水锁问题是气藏开发中的技术难点。

苏里格气田东区（简称苏东地区）属于典型的低渗致密气藏[5]，气田开发面临的突出问题是积液气井的比例不断上升，截止到2016年底，积液气井比例高达79.6%，高液气比条件下水锁伤害更为严重，造成大量的气井产量明显下降甚至停产，目前常规成熟的排水采气工艺措施，无法有效恢复气井产能。导致苏东地区水锁的原因是什么，怎么准确判断气井是否发生水锁，如何有效针对水锁气井制定相应的解除水锁伤害？这些问题的解决，对于有效指导苏里格气田东区气井水锁伤害的治理及有效恢复气井产能，具有非常重要的理论价值和实际意义。本文在充分调研前人研究的基础之上，分析苏东地区水锁产生的机理，以苏东地区储层特征和采气曲线特征为出发点研究总结气井水锁判识方法，为相似区块制定快速的水锁诊断技术及相应的水锁防治方案提供基础依据和经验借鉴。

1苏东地区气藏基本特征

苏东地区是苏里格气田向东部方向的延续，为典型的“苏里格型”气藏，资源丰富，开发潜力大，开发难度高，勘探面积为6000km2，气藏勘探目的层主要为盒8、山1，兼探盒4、山2、本溪组、马家沟组，具有多层系含气的特点。

苏东气藏储层岩石孔隙结构复杂，孔隙类型多，分选中等，小孔喉占比例大，孔径小于0.1μm的频率在

陈存良等苏东地区气藏水锁机理分析及水锁判识

第5期55