异常高地应力致密砂岩储层压裂技术研究

FRACTURING TECHNIQUES OF TIGHT SAND RESERVOIRS WITH ABNORMAL HIGH EARTH STRESS

随着勘探的不断深入,首次在新探区采用压裂技术时难度越来越大,部分井岩性致密,加之地应力异常高,导致压裂施工时在低排量情况下施工压力非常高,无法加砂而使压裂施工失败,达不到改造和认识储层的目的。文章以武1井为研究对象,该井为吐哈油田在民和盆地的一口探井,第一次压裂因施工压力异常高,在1.3m3/min排量下井口压力达到83.3MPa,支撑剂根本无法进入地层而未获成功。通过分析武1井首次压裂失败的原因,研究并采取了高能气体压裂、酸化解堵等近井筒处理措施和小粒径支撑剂、支撑剂段塞、优化泵注程序等针对性工艺,使第二次压裂施工获得成功,加砂26.04m3,压后日产水5.0m3,日产气2000m3,这对类似储层的压裂改造积累了宝贵经验。

As exploration goes deeply, it is more and more difficult to conduct fracturing primary at the new exploration area. Since the lithology is tight and the earth stress is abnormally high for some wells, which makes the fracturing job fail due to the operation pressure is very high under low flow rate while fracturing so that the gravel input can't be performed, the purpose of reforming and understanding the reservoir can't be reached. The article takes the well Wu 1 as the research object. The well is an exploration well in Minhe basin of Tuha oilfield, Its primary fracturing job is fail because the gravel input can't be performed due to very high working pressure, i. e. the wellhead pressure reaches 83. 3 MPa at 1. 3 m3/min. of flow rate. With analysis of the failure, the countermeasures such as the processing measures near the borehole of fracturing with high-energy gas, broken down with acidizing etc., and the techniques of small grain proppant, proppant slug, optimized program of pump injection etc. are applied, which make the second fracturing success: the gravel input 26. 04 m3, the water producing 5. 0 m3/d and gas producing 2000 m3/d after the fracturing. The article provides valuable experience for fracturing stimulation of similar reservoirs.