The Nine <sub> 6 </ Sub> District Qigu Special Heavy Oil Reservoir To Improve Steam Flooding Effect

As the qigu fm of heavy oil reservoir in Nine-six district being putted in exploitation in Jun 1989, it has successionally experienced steam stimulation in early stage, steam-activated, refined stimulation and full scale infilling for these years. in May 1998, for efficient developing this extra heavy oil reservoir, steam driving has been largely applied in this area, but as the time gone, some problems emerged in the latter stage, such as gas migration, water breakthrough, steam overlapping, high water cut and so on, these phenomenon seriously affected the economic benefit of producing.For survey the remaining oil, take further researches on the developing efficiency and the restriction of steam flooding in intermediary and later stage, confirm the potential produce capacity, and take effective measures for special area and particular geologic feature, this paper used numerical analogue as the main approach and combined the reservoir engineering methods and the investigation in the early stage for the characteristics of present wells, which behave long producing history, large amount of wells, and complex exploitation status. Therefore, it is necessary to scrutiny the reservoir, accurately predict the remianing oil distribution and formulate proper development program, and which are significant for the research on steam driving in the same type reservoir.The main result just as follows:(1) Fine reservoir description results show that: J₃q² of Nine-six area in part of wells is partial penetration, while local area of J₃q³ under J₃q² is rich domain, the bearing area is 1.9 km², geologic reserve is 208×10⁴t, net thickness is greater than 5m², and the average thickness is 9.2m. Reserve replacement in local area can be realized by reperforating and extraction. Until Dec. 2008, there are twenty two wells has been carried out reperforating and extraction, and the 12554t accumulation production increment shows that deserves.(2) 96988 core well of qigu fm in Nine-six district which is located in the south of the reservior, it is completed in August 11, 2004, the total depth is 280m, the core interval is from 204. 33m to 227. 43m in qigu fm. The recovery in this area is 53% before drilling inspection well. The measure of remaining oil satruation shows that the average oil saturation is 46%, which is less than the initial value 74%. (3)This paper carried on the research of optimization production parameters and draw manage principle from the accurate geologic analysis and remaining oil distribution, as well as the dynamic analyze the main problem in reservoir exploitation, finally improved the effeciency of steam flooding in intermediary and later stage of developing by means of plug-in gas flooding technology with continuous gas injection, implusion injection, intermittent gas flooding and discontinue gas flooding.(4)The recovery qigu fm in Nine-six district has been greatly improved by plug-in steam flooding technology. From 2000, the production was exceeding 10t, the annual steam/oil ratio is over than 0.1, it has realized stable yields for 8 years, and it also has pioneered the large scale steam flooding in extra heavy oil reservoir of our country, and presents new exploitation plan for steam flooding in extra heavy oil reservoir.