Surface Process Of Carbon Dioxide Flooding In YSL Oilfield

In recent years, the Co₂ EOR technology has developed rapidly. Studies have shown that the Co₂ injection not only can greatly improve the recovery factor, but also can achieve the purpose of CO₂ emission reduction, meet the requirements on environmental protection and reservoir high-efficient development. As a result of technological progress and the influence of greenhouse effect, CO₂ EOR technology have received more attention than ever before, many countries including China have carried out field experiments. Currently, CO₂ EOR has become a leading technology to enhance oil recovery factor in the United States. In 2004, the annual increased oil production contributed by CO₂ EOR technology took 31% of total number of EOR production.YSL oilfield is located in the northeastern extremely cold region of China, the minimum temperature is about minus 39.2 ℃. Annular oil mixing water process is the most economic and effective way of oil gathering and transportation manner. But for CO₂ flooding, the injected and produced water will meet the challenges of frozen, blocking, corrosion and other issues to impact the regular production of gathering and transportation system. In order to ensure the safe and stable production and reduce the investment on surface facilities, and to maintain the economic benefits of oilfield development, it is urgent task to develop a totally-enclosed annular oil mixing water system for extremely cold area.YSL oilfield has begun to launch CO₂ flooding pilot test in Shu 1 Block in 2007 and Dong 2 and 3 Blocks in 2011. In 2014, YSL oilfield carried out the CO₂ non-miscible-phase displacement industrialized experiment for low porosity and permeable reservoir. Up to now, the cumulative well number of CO₂ flooding well pattern is 201, including 133 production wells and 68 injection Wells. One CO₂ flooding surface system transferring station, one concentrated liquid injection station, one CO₂ liquefaction station, six gas distribution rooms, three metering rooms, six water injection rooms and 39 elevated oil tanks has been built in YSL oilfield. The second stage construction of the project will build the CO₂ recycling system and Shu 1 sealed gathering and transportation system. At that time, YSL oilfield CO₂ flooding experiment area will realize completed sealed transportation, recycling and utilization and also can achieve the goal of carbon dioxide storage and oil high efficient displacement at the same time.Co₂ flooding of YSL oilfield have achieved better stimulation effect at various degree, but the produced gas has not been purified and liquefied due to the small scale of test area, and the matching technology of produced Co₂ gathering and transportation and re-injection still need more research and exploration. We need to launch expanding field test to evaluate the effect and optimize the matching technology of Co₂ flooding, the ultimate aim of YSL oilfield is to industrial promote Co₂ flooding in Fuyang ultra-low permeable reservoir.The success of Co₂ injection field test can be a new way for the effective development of 565 million tons（168 in Hailaer Oilfield） of OOIP with permeability lower than 2mD in the peripheral oil fields of Daqing. In addition, 309 million tons with permeability between 2 to 10 mD can use Co₂ injection to further improve EOR after water flooding.