海上稠油蒸汽吞吐开采技术实践及认识

Practice and understanding of steam huff and puff recovery technology for offshore heavy oil

渤海油田稠油资源丰富,地层内粘度高于350 mPa·s的稠油冷采开发产能低、采收率低,难以满足海上高效开发要求。为探索海上规模化高效热采技术,以LD油田明化镇组稠油为靶区,开辟首个海上蒸汽吞吐先导试验区。与陆地不同,试验区具有以下特点:天然能量开发有一定产能(20 m^3/d)、井距大(400 m)、井控大(45×10~4 m^3)、水平井开发等。根据开发难易程度,进行了储量品质分类研究,建立了底水和边水油藏均质模型,研究了蒸汽吞吐的布井界限,设计了12口热采井整体方案,并从2014年分步实施。目前有两口井已分别进入第二轮和第三轮吞吐。由于海上开发的经济性要求、开采特点等与陆地不同,在现行蒸汽吞吐效果评价标准基础上,增加了热采有效期等具有海上特色的评价指标,总结了海上多轮次蒸汽吞吐开发规律,并积累了降低稠油乳化风险的经验。试验区取得的认识及成果对海上稠油后续规模化高效开发具有重要指导意义。

Bohai Oilfield is rich in heavy oil resources, and the cold recovery of heavy oil with viscosity higher than 350 mPa · s in formation is low, so it is difficult to meet the requirements of efficient offshore development. In order to explore the large-scale and efficient thermal recovery technology at sea, the first pilot test area of offshore steam huff and puff was opened up by taking the heavy oil of Minghuazhen formation in LD Oilfield as the target area. Different from land, the test area has the following characteristics: natural energy development has a certain productivity(20 m^3/d), large well spacing(400 m), large well control (45×10^4 m^3), horizontal well development, etc. According to the difficulty degree of development, the classification of reserves quality was carried out. The homogeneous model of bottom water and edge water reservoirs was established. The well layout boundary of steam huff and puff was studied, and the overall scheme of 12 thermal recovery wells was designed, which was implemented step by step from 2014. At present, two wells have entered the second and third rounds of huff and puff respectively. Due to the different economic requirements and recovery characteristics of offshore development from those of the land, the evaluation indexes with marine characteristics such as the validity period of thermal recovery are added on the basis of the existing evaluation standards for steam huff and puff effect. The development rules of steam huff and puff with multiple rounds at sea were summarized, and the experience of reducing the risk of heavy oil emulsification was accumulated. The understanding and results obtained in the test area are of great guiding significance to the follow-up large-scale and efficient development of offshore heavy oil.