金家油田低渗敏感稠油油藏适度出砂室内评价

Laboratory evaluation on reasonable sand production of low permeability sensitive heavy oil reservoir in Jinjia Oilfield

低渗敏感稠油油藏作为一种特殊类型的稠油油藏,由于其储层渗透率低、敏感性强、油稠、出砂等原因,导致注汽热采困难,生产井供液严重不足,无法实现油藏的有效动用。在对油田开发效果的主要影响因素进行分析的基础上,利用真实岩心开展了水驱、热采、CO2辅助热采等不同开采方式的驱替实验效果评价,利用CT、扫描电镜等方法对出砂前后的物性变化特征进行了定量评价。实验表明,常规水驱、蒸汽驱均可导致储层出砂,热采方式的出砂量明显加大,CO2辅助蒸汽驱在储层中可形成类似于出砂冷采的蚯蚓洞,明显改善了储层物性,提高了开发效果。从岩心入口端至出口端,蚯蚓洞的形成经历了生成-发展-萎缩的过程。对于高黏土低渗敏感稠油油藏而言,适度出砂不失为一种改善井底渗流条件的有效开发方式,对同类油藏的开发具有一定借鉴作用。

As a special type of heavy oil reservoir, low permeability sensitive heavy oil reservoir is difficult to be developed by steam injection and thermal recovery because of its low permeability, strong sensitivity, heavy oil and sand production, and its liquid supply in production wells is seriously inadequate, which makes it impossible to realize effective reservoir production. Based on the analysis of the main controlling factors of poor oil field development effect, water flooding, thermal recovery and CO2-assisted thermal recovery were carried out in real cores to evaluate the development effect. The physical properties before and after sand production were quantitatively evaluated by means of CT and scanning electron microscopy. Experiments show that conventional water flooding and steam flooding can lead to sand production in reservoirs;sand production in thermal recovery mode is obviously increased.Earthworm caves similar to cold sand production can be formed in reservoirs by CO2-assisted steam flooding, which can obviously improve reservoir physical properties and improve development effect. From the entrance to the exit, the formation of earthworm caves undergoes a process of generation, development and atrophy. For high clay and low permeability sensitive heavy oil, moderate sand production is a development method to improve bottom hole seepage conditions, which can be used for reference in the development of similar reservoirs.