关键词: 低渗透难动用储量, 压裂, 经济评价, 风险性分析, 专家系统, 数据库

Abstract: A hydraulic fracturing expert system for the low-permeability and undeveloped oil-bearing reservoirs is developed according to the characteristics and development difficulty of reservoirs.The system contains database of undeveloped oil-bearing reservoirs,economic risk analysis of overall hydraulic fracturing using Monte-Carlo method,quick evaluation of irregular well pattern and fitted fracture system,automatic optimization of fracturing design plan based on the theory of genetic algorithm,optimization of flowing back of fracturing fluid and bottom-hole flowing pressure.The field pilot tests were performed,in order to decrease fracturing cost and improve the production rate of single well.The new techniques include optimization of well pattern considering in-situ stress orientation,combined pumping technique using various low-viscosity and low-damage fracturing fluid and various types of proppant,layering fracturing,large proppant weight fracturing combined with water flooding at early time,water fracturing technique as well.Above techniques were put into field applications in Qian-48 Block of Jilin Oilfield,Keramay Oilfield of Xinjiang area and Dongzhi Oilfield of Changqing area.The post-fracturing effects were all satisfied.The production rate of single well increased by 34 percent,while the fracturing cost decreased by 37 percent in Jilin Oilfield.Again in Keramay Oilfield,the average post-fracturing rate was twice as large as before.The early water flooding in Dongzhi Oilfield also shows an ideal result.

Key words: low-permeability and undeveloped oil-bearing reservoirs, hydraulic fracturing, economic evaluation, risk analysis, expert system, database