The Evaluation Committee of Zhongyuan Oilfield Technology Department had a technical achievement evaluation on the project “Research on high-temperature-resist and high-salinity-resist microsphere deep profile control technology” (evaluation number 2010308), and the suggestions are as follows:
¢ñ. The main research work
1. On the base of the research on the mechanism of the reservoir deep profile control, our company has developed high-temperature-resist high-salinity-resist gel microsphere profile control technology system, which satisfied the requirement of the deep profile control of Wenzhong oilfield.
2. Choosing the rock core of Block Wen10 to do the reservoir adaptability experiment of the gel microsphere has optimized the system of gel microsphere.
3. In the on-site experiment of microsphere profile control, by optimizing the design and perfecting the operating process and the dynamic adjustment microsphere system, the microsphere in-depth profile control technology system has come into being, including the oil recovery enhancement in the late period of the development of the high water content oil field.
¢ò. Main innovation points
1. The high-temperature-resist high-salinity-resist microsphere profile control system has been successfully developed, which has relatively strong temperature-resist£¨<105¡æ£©, salinity-resist£¨<29×104mg/l£©, and anti-shear properties, and can meet the on-line injection of high-temperature high salinity oil reservoirs.
2. Adopt FD (filling degree) as the judging standard of the adequacy degree of the reservoir profile control. Concerning those wells whose FD value£¼0.65, through controlling the profile and plugging the water in the near-well-bore areas in the early stage to improve the FD value and then carrying on deep profile control, the profile control effect is obviously improved.
3. Adopt “PI+FD deep profile control comprehensive decision-making technology”. According to the dynamic statement of the PI and FI value in the process of profile control, the injection parameters (four “degree”) of the microsphere will be adjusted in several phases in order to make the microspheres enter the deep formation step by step, perfect the contradiction between the inner layer and interlayer of the oil reservoir and improve the sweep efficiency of the injection water and enhance the oil recovery.
¢ó. Application conclusions
The project launched scientific research breakthrough endeavor on microsphere deep profile control. The microsphere was applicable to 7 well groups in Wenzhong oilfield. Compared with the statement before profile control, the average injection pressure increased by 6.7MPa, the filling degree of the formation increased by 0.16, the measuring water intake profile started new layers 6n/10.5m and control high-permeability layer 7n/14.2m, the producing reserve of the water flooding increased by 21.35×104t, the natural decline of the well groups dropped by 17.4%, the comprehensive water content dropped by 2.6%, 13 out of the corresponding 14 wells were effective, and the oil increased by 3258.1t accumulatively. This project improved the matching technology methods of the producing degree of the water flooding, which is significant to the oil recovery enhancement in the late period of the high water content phase in the similar complicated fault block.
¢ô. Overall evaluation
According to the evaluation committee, this project launched the research targetedly, solved the manufacturing difficulties, and offered complete materials and accurate data. The acceptance was passed.
¢õ. Existing problems and improvement suggestions
Up to now only 7 well groups have been done the microsphere deep profile control experiment, and seldom blocks were applicable. It is suggested that the microsphere system should be further perfected and the experimental scope should be broadened to satisfy the need of deep profile control in the high water content oilfield in the late period.
Bingnan Oil Production Plant organized experts to do inspection and performance appraisal on the project Pilot Test on Block Bing5.
The oilfield exploration and development division of Bingnan Production Plant organized experts to do inspection and performance appraisal on the project Pilot Test of the Microsphere Deep Profile Control Technology of the High Temperature Low permeability Reservoir on Block Bingnan5 that was undertaken by our company. After the discussion of the expert group, there were the following ideas:
¢ñ.Main researches and achievements
1. The preparation of the high-temperature-resist gel microsphere was accomplished. Adopting the method of microemulsion polymerization multivariate copolymerization can improve the temperature-resist property of the microsphere. Put under the condition of 120¡æ for 6 months, the plugging retention of the microsphere reaches 90.7%. The microsphere is characterized with good thermostability.
2. The preparation of the synthetic equal size microsphere with different strength was accomplished. The proportion of the control system was 50%. The initial size of the microsphere between 0.4 to 0.7μm was attainable. The strength of the microsphere is controllable by adjusting the cross-linking ratio. The plugging ratio of those rock cores with 0.1% cross-linking ratio is higher by 7.2% than that with 0.05%.
3. It was on May, 2009, January, 2010, June, 2010, September, 2010 respectively that the normal injection water wells of Block Bing5 was done with wellhead pressure decline measurement. Based on the decision result, the operating well number of each round was chosen, and the decision data was used of to improve the project.
4. The research on the water channeling rules of Block Bing5 was accomplished with the help of tracer agent. Through injecting tracer agent and measuring it in the well Bing5-11, describing 38 pathways of the corresponding 5 oil wells totally, including 6 channeling pathways, it showed that the physical properties of the formation of Block Bing5 had changed obviously due to long-term injection erosion, and there was channeling pathways between the water well and oil well. It was suggested to adopt the operating pattern “Channeling plugging far drive” under the condition, namely, the combination of plugging agents was more effective.
¢ò. On-site experimental effect
The oilfield experiment in these wells such as Bing5-12, Bing5-13 and Bing5-Xie28 was accomplished by making use of PI decision technology. All the three well groups made good effect. By far the overall water content of the well group has dropped by 8.2% after the profile control, and the accumulative increased oil is 3724t.
¢ó. Overall evaluation
According to the expert group, on the base of scientific and reasonable technical ways and experimental scheme, complete inspection materials, and satisfactory research content and technical specification which met the requirements of the agreement, the inspection and acceptance was agreed to pass. It suggested that it should be widely applied in other similar high-temperature low-permeability reservoirs.