Optimizing Design For Thermal System Efficiency Of Steam Stimulation

Heavy oil resources are very rich in the world, exploiting heavy oil with reason and efficiently has an important impact on alleviating the world energy crisis. Steam stimulation is the main development mode of heavy oil at present, which needs complicated technology, huge investment and has more economic risks on development than the regular reservoirs. So the various parameters of steam stimulation must be compared and analyzed, and thermal system must be optimized before exploitation. Based on the introduction about recovery mechanism of steam stimulation, the main effects are analyzed which affect steam stimulation effectiveness. The measures used to reduce wellbore thermal loss and formation thermal loss are proposed through studying the mechanism and calculating method of wellbore thermal loss and deformation thermal loss during steam stimulation. The calculation methods of wellbore thermal loss, bottom hole steam quality, and overall thermal transfer coefficient are gave, which can provide conditions for calculating formation thermal loss, reservoir heating radius and oil well productivity. The study of impact of heating radius on steam stimulation effectiveness in the soak period is conducted, and the determination method of reasonable soaking time is introduced. Analyse and improve limits and shortages in Boberg and Lantz analysis of predicting oil well productivity, which make the oil well productivity predicted more in line with actual situation. Analyze and selecte the main injection and production parameters which affect heavy oil steam stimulation effectiveness, such as steam injection rate, steam quality, cyclic steam injection volume, injection pressure, soaking time and bottom hole production flowing pressure. Using the greatest thermal system efficiency as the objective function, the injection and production parameters above-mentioned are optimal designed and calculated. This paper provides calculation criterion and analysis methods for the optimization of steam stimulation thermal system and injection-production parameters and therefore the development efficiency of steam stimulation is improved, while the development risk of steam stimulation is reduced.