Research And Application On CHOPS (Cold Heavy Oil Production With Sand) Technology

Heavy oil resource is abundant in China. Annual production of heavy oil is more than 1300*10~4 tons, account for 10% of total oil production in China. China is one of the four heavy oil producers in the world. Heavy oil resource is very rich in Jilin Province, which mainly located in western slope of southern Songliao Basin. OOIP (original oil in place) of western slope is 4.83 * 10~8 tons according to secondary resource assessment. Proved OOP is 1.41 * 10~8 tons in tertiary resource assessment zones. Submitted proved OOIP was only 2046 * 10~4 tons in Taobao oilfield. There are great prospective in exploration and development in western slope of Songliao Basin.At present, development fashion of domestic heavy oil reservoirs is mainly steam huff and puff recovery, with serious challenges of high cost. Specially, Taobao oilfield in western slope of Southern Songliao Basin has factors of thin pay zone (3-10 meters), shallow burial depth (280-320meters), thin barriers and interlayers, unconsolidated sandstone, active bottom water and edge water, and other unfavorable features. So, in the prophase of research and test, the difficulties are low production rate of convention cold heavy oil production, poor thermal recovery profit and upward breakthrough of bottom water and lateral water, and so on. Field tests of heavy oil development are very difficult due to unfavorable geologic features, without examples of successful development in the reservoirs with same geologic characteristics in domestic and abroad. High efficiency development of heavy oil reservoirs in Jilin Daobao oilfield has great significance in enhancing resource utilization ratio and increasing reserves and production rate.In order to develop efficiently the heavy oil resource in Daobao oilfield, we engaged the research to the oil reservoir geology and the development technology, in reservoirs geology, developing the research of pay zone correlation, depositional tiny facies, structural characteristics and structural developing history, reservoir bed characteristics, fluid property, reserves situation, in technological aspect, developing the research of cold heavy oil development test blocks, thermal recovery blocks, CHOPS blocks, preventing upward breakthrough of bottom water, and so on.Against the engineering and technical difficulties in Daobao heavy oil development, on the basis of research in the domestic and international research data, geological and technology were combined , the laboratory and field test were combined, after five years of research and testing, the three main problems have been solved by adopting CHOPS technology in Jilin heavy oil reservoir. Firstly, high-efficient development fashion problem in the special thin heavy oil reservoirs with shallow depth is solved. CHOPS technology has been determined as the optimum development fashion through 5 years trial field tests; secondly, upward channeling problem of bottom water has been solved. Drilling technology at certain depth completion without drilling through barriers has been selected finally,which is based on 8 advanced cementing techniques at home and abroad and drilling tests without drilling interlayer between oil reservoirs and aquifers (exploitation more than 90% OOIP), the bottleneck problem of upward channeling of bottom water has been basically solved; thirdly, productivity breakthrough has been carried out, perforation technology with large diameter, high density, sand stimulation technology that can keep oil well high and stable production rate is adopted. Productivity of individual well can be increased by 10 times of that of conventional cold production methods(sometimes 20-30 times in some wells), and 5 times of that of thermal recovery. Productivity breakthrough has been carried out. CHOPS has very great profit.There are five technical innovation points in CHOPS technology in Jilin heavy oil reservoir.First, the difficulty in developing the thin shallow heavy oil reservoir has been solved. By three development test mode, CHOPS is confirmed the optimum development methods in Jilin Daobao heavy oil reservoir.Second, all kinds of the technical parameters of high efficient perforation technology that suit CHOPS technology have been optimized and confirmed.Third, Developed the perforation technology with large perforation diameter and high perforation density, and the sand stimulation technology maintained production rate or increased production rate.Fourth, Solved the problem of upward channeling of bottom water, Summed up the development drilling technology at certain depth completion in order to prevent upward channeling of bottom water.Fifth, a series of unique surface oil and gas gathering technology of viscous sandy heavy oil in Taobao oilfield, dehydration, sand washing and treatment process of sandy heavy oil have been put forward.CHOPS technology has wide application potential in Daobao heavy oil reservoir. Matched development technologies have been adopted in 54 wells from 2006 to 2007. Daily production rate of individual well enhanced greatly, average daily production rate of individual well is 8.2 tons, daily production rate of individual well of 60% wells were more than 10 tons, the highest daily production rate of individual well is 30 tons. Equivalent daily production rate is 15-16 tons per one thousand well depths. Four-month cumulative production is 10 times of that of conventional cold production, 4.5 times of that of steam huff and puff recovery.Mature heavy oil development technologies speed up the process of exploration and development of western slope. There are 880 development wells, with producing area of 43 km~2, producing OOIP of 3348*10~4 tons in 8 blocks in Taobao oilfield. Annual productivity is 16.47*10~4 tons. CHOPS technology can be widely applied and promoted in heavy oil reservoirs with the same geologic features at home and abroad.Great economic benefit has been achieved by adopting CHOPS technology. Cumulative profit is 1.2581 billion Yuan. Productivity is 16.47*10~4 tons. Oil production rate is 13.2*10~4 tons. Annual profit is 1.16557 billion Yuan, increasing 1.2936 billion Yuan profit than that of last year.