哈拉哈塘碳酸盐岩储层井壁失稳动态评价及失稳形态分析

井壁失稳是碳酸盐岩储层钻完井及开发过程中十分常见的工程难题。塔里木盆地哈拉哈塘油田奥陶系碳酸盐岩油藏油井井壁失稳、出泥砂严重,井壁失稳给油井投产、生产等带来一系列问题。为了对失稳现象进行有效分析,明确失稳来源和失稳形态,发挥油井产能,基于工程表象和作业数据提出井壁失稳程度动态评价指标体系,在生产动态和探冲砂作业基础上,形成井壁失稳动态评价方法。利用井壁失稳程度的动态评价方法分析109口失稳井的井壁失稳特征,借助冲捞砂样和储层岩心分析井壁失稳形态。结果表明,哈拉哈塘油田失稳主要为非生产层组的垮塌和生产层组裂缝、孔洞中充填泥砂的产出,失稳形态主要以坍塌掉块和流体携带泥砂产出为主。钻新井时先对产层采用悬挂筛管防砂完井,封隔吐木休克组等易坍塌地层,再对老井的裸眼井进行探泥砂、冲捞砂作业,清理沉积物获得产能并进行合理参数的筛管二次完井。

Dynamic evaluation of wellbore instability and instability form analysis of Harahatang carbonate reservoir

Wellbore instability is a very common engineering problem in the process of drilling, completion and development of carbonate reservoirs. In the Ordovician carbonate reservoir of the Halahatang oilfield in the Tarim Basin, the borehole wall instability and mud sand production are serious. The wellbore instability has brought a series of questions into production, such as low opening rate, high difficulty of operation, and large loss of productivity. In order to effectively analyze the instability phenomenon, clarify the source of instability and the form of instability, and give full play to the productivity of oil wells as soon as possible, based on production performance, sand exploration and flushing operation, a dynamic evaluation method of wellbore instability is formed. Using the method of dynamic evaluation of the degree of wellbore instability, the Halahatang wellbore instability law and correlation analysis were carried out on 109 unstable wells, and the wellbore instability pattern analysis was carried out by using washed sand samples and reservoir cores. The results show that the main factors affecting sand burial are the open hole completion, whether the open hole section of the Tumuxuke formation is completely blocked, and the hole size. The instability of the Halahatang Oilfield is mainly caused by the collapse of the non-productive layer group and the production of the sand filled in the cracks and pores of the productive layer group. The instability patterns are mainly caused by collapsed blocks and fluid-carrying mud and sand. It is recommended that when new wells are drilled,suspended screens should be used for sand control completion in the pay zone first, and the Tumuxuke formation and other vulnerable formations should be sealed. For open-hole wells in old wells, sand exploration and sand scouring operations are carried out, and screen completion with reasonable parameters is carried out to clean up and obtain productivity.