基于CO2特性的无水加砂压裂技术研究与应用

Research and application of water free sand fracturing technology based on carbon dioxide characteristics

关键词:  CO₂无水加砂压裂  增稠剂  加砂方式  工艺流程  现场试验

Key words:  carbon dioxide anhydrous sand fracturing  thickener  sand adding mode  process flow  field test

摘要:

吉林油田致密油资源潜力大,储层物性差,常规水力压裂改造技术易造成储层污染、能量补充不及时,油井产量递减快。CO₂无水压裂技术具有增加地层能量、降低储层伤害、原油混相等技术优势。基于液态CO₂压裂液体系的黏度、携砂性及滤失特征方面的研究,开展了CO₂无水压裂技术加砂试验。通过优选增稠剂Ⅱ型压裂液提高CO₂的黏度,采用段塞与连续加砂相结合的加砂方式、优化前置液比例,完善加砂工艺,提高加砂规模,压裂液体系黏度增加15～45倍,效果明显好于增稠剂Ⅰ型。CO₂无水加砂压裂技术实施的10口井压后日产油是常规重复压裂的2倍以上,折算单井节约水资源1 512 m³。 

Abstract:

Jilin oilfield has great potential of tight oil resources and the reservoir physical property is poor. The conventional hydraulic fracturing technology was easy to cause reservoir pollution, and delayed the energy supplement, so the oil well production declined rapidly. Carbon dioxide water free fracturing technology has the advantages of increasing formation energy, reducing reservoir damage and mixing crude oil. Based on the study of viscosity, sand carrying capacity and filtration characteristics of liquid carbon dioxide fracturing fluid system, sand adding test of carbon dioxide anhydrous fracturing technology is carried out in this paper. Through optimizing thickener type II fracturing fluid to enhance the viscosity of carbon dioxide, adopting the sand adding method combining slug with continuous sand adding, optimizing the proportion of pre-fluid, perfecting the sand adding process, and increasing the sand adding scale, the viscosity of fracturing fluid system is increased by 15-45 times, and the effect is obviously better than that of thickener type I. By using carbon dioxide water free sand fracturing technology, the daily oil production of 10 wells is more than twice of the conventional heavy pressure, and the water resources of a single well can be saved by 1 512 m³.