Study On Key Technologies To Recover Heavy Oil By Aquathermolysis

The resource of heavy oil and oil sand is three times than that of conventional oil in the world, and it will be the main energy source in the future for most of it is not recovered and the conventional oil is rapidly depleted. However, it is difficult to recover heavy oil because of its high viscosity and poor flowing ability. Aquathermolysis is a new and potential technology to recover heavy oil, especial the extra heavy oil, which should combined with thermal technologies such as steam injection. The key technologies of aquathermolysis required were researched in this dissertation. It includes aquathermolytic catalysts, increasing the reservoir temperature in situ, upgrading and enhancing technology involving hydrogen donor, and practical technics and technologies. It could be found that Liaohe and Shengli heavy oil were extra high in viscosity and resin content (the total content of resin and asphaltene is close or over 50%), The viscosity, resin and asphltene contents, and metal contents of Liaohe heavy oil are greater than those of Shengli heavy oil, but the sulphur content of former is lower. It noticed that the higher viscosity of heavy oil may be derived from not only its larger content of resin and asphaltene, also the complex compounds contained, molecular aggregation and polarity. Heavy oils were upgraded by aquathermolysis chemically for some molecules in heavy oils were changed, the aquathermolytic reaction could be enhanced by extending reaction time and/or increasing reaction temperature, accelerated by formation minerals, and improved by alkaline matters. Treated by aquathermolysis the viscosity of Liaohe and Shengli heavy oils was decreased, average molecular weight and contents of resin, asphaltene and sulphur also decreased. The aquathermolytic reactivity of Shengli heavy oil is greater than Liaohe heavy oil, and it was upgraded greater. In aquathermolytic reaction of heavy oils, it involves the reactions between organic sulfur compound and water/steam, the reaction of metal complex compounds, and the reaction involving free radicals generated. The water gas shift reaction (WGSR) is an important and elementary reaction in which hydrogen could be generated, and the hydrogen is necessary for hydrogenating desulfurization. The aquathermolytic reaction, especial the WGSR could be accelerated by high temperature water, formation minerals, metal in heavy oil or added. Some side alkyl chains could be removed in aquathermolysis. At the same time, the polymerization reactions could be promoted in acid environment. In the key technologies of aquathermlysis researched in this thesis, thermochemical heating technology could increase the reservoir temperature in situ effectively, Addition of effective catalyst, hydrogen donor and alkali solution could accelerate or enhance the cleavage reaction and upgrading reaction in aquathermolysis, as a result, the heavy oils were upgraded, and the production and recovery increased. At last, the practical technics and technologies are feasible for aquathermolysis testing in oilfields. The cheap and efficient catalyst developed could decrease the activation energy of aquathermolysis, increase the reaction rate, and heavy oils were upgraded evidently. As a result, the viscosity was decreased over 70%, the content of resins and asphaltene lowered, the content of saturated and aromatic hydrocarbons increased, the structure changed obviously. It shows that minerals and catalyst developed have synergetic effect on aquathermolysis(up to 80% decrease in viscosity of Liaohe and Shengli heavy oils observed), and alkali solution could also promote the reaction. To increase steam injection reservoir temperature, the thermochemical heating technologies were investigated, which involves adding hydrogen peroxide (H2O2) or adding NaNO2 and NH4Cl/ NH4NO3 at the same time. The technologies could efficiently increase the temperature of steamed reservoir with many advantages such as lower loss of heat, simple procedure and practical technics, easy to control and so on. Addition of H2O2 is favorable to reduce the content of asphaltene and sulphur in aquathermolysis, and addition of NaNO2 and NH4Cl/ NH4NO3 could generate a mass of gas that is very helpful. The hydrogen donor HD-1 was developed from some polycyclic aromatic compounds, some petroleum fractions generated in refinery as a sideproduct. It is cheap and capable to supply hydrogen in aquathermolysis. Addition of HD-1 could accelerate the reaction and shorten the reaction time, andincreasing reaction temperature is more effective than extending reaction time for its hydrogen supply. It shows synergetic effect on aquathermolysis with catalyst developed. Addition of HD-1 could enhance the cleavage reaction and upgrading reaction, restrain the polymerization/ condensation reactions, reduce the gas production, and increase the recovery ratio of saturated and aromatic hydrocarbons favored. It is feasible to select wells for aquathermolytic field testing by fuzzy and matter element method. The practical technics of aquathermolysis include single well stimulation and flooding. The technics and technologies related were introduced or recommended in detail such as recovering technics, surface technological process, reservoir process in place, preparing and safety of chemicals used, practical process design, operation procedures, and so on. The aquathermolytic field testing were applied to 20 wells in Liaohe Oilfield. The total cumulative oil production increased in the testing cycle is 11009.4 tons, an average of 550 tons per well, the ratio of cost to income up to 1:5. The oil production increase is larger, and the production performance of testing wells improved obviously. The viscosity, components and structure were changed evidently, and heavy oil of testing wells upgraded. Up to 80% decrease in viscosity was obtained for wells treated by aquathermolysis. In conclusion, heavy oil could be upgraded greatly and recovered by aquathemolysis with the effective and feasible key technologies investigated in this thesis. As a result, the heavy oils were cleaved and upgraded, viscosity reduction obtained, the recovery enhanced or improved. The technology to recover heavy oil by aquathermolysis is reinforced by this research, and it is potential and commercial to recover heavy oil, especial extra heavy oil by aquathermolysis in the near future.