The Research Of Self-heating Plug Removal Agent And Discussion On Aluminum-water Reaction As Hydrogen Donor

Organic deposits are one of the difficult problems faced by stimulation and stable production in oilfields and development of heavy oil. The organic deposits in near wellbore area is the main reason of reduce production of wells, and asphaltene often consider as an inconvertible hurt. Conventional methods of Remove Plug are not able to effectively remove the organic deposits in near wellbore area, especially the asphaltene. Common thermogenic technology can heat the near wellbore area, and remove wax. If catalyzator, hydrogen donor and additive are added, the aquathermolysis of asphaltene can occur, and the organic deposits can be removed. The feasibility and effective of this technology is proved by the experts of Ukraine.Aquathermolysis is the action between heavy organic and water (include liquid and gas), include acid polyreaction, water gas shift reaction and hydrodesulfurization reaction. The broken of C-S bond of asphaltene is the most important step of aquathermolysis. Aquathermolysis generally occur in the range of temperature 200-300℃. Use this reaction can degrade asphaltene in a low temperature, and achieve the aim of remove plug and viscous oil modification. And there is researches show that the aquathermolysis can occur at 180℃, the asphaltene with low sulfur content can also occur this reaction. The influencing factors of aquathermolysis include: temperature, reaction time, hydrogen and catalyzator.In this work, after comparing different self-heating exothermic chemistry systems, with the help of Ukrainian experts, use NaNO2 and NH4NO3 exothermic system, with addition of catalyzator, hydrogen donor and additive, to prepare a group of solutions, which is composed by two solutions:УК-130 andУК-160. They are design to remove plug in the near wellbore area. The solutions of NaNO2 and NH4NO3 with concentration of 6mol/L are able to raise the temperature of base fluid more then 200℃. After comparing, show that theУК130-УК160 system has more enhanced exothermal ability. And theУК130-УК160 system can react in weak acid environments, so can reduce corrosion of well and this can increase the service life of well.The addition of hydrogen donor can promote the reaction of aquathermolysis. The hydrogen evolution reactions of common hydrogen donors are endothermic reaction. While Modify heavy oil under the steam injection, the heat absorbed by hydrogen donor can be neglected. But in the conditions of self-heating removing plug in single well, in order to improve the utilization of energy, it is better use the hydrogen donors, which release heat in the process of hydrogen evolution. Active metals are able to react with water, in the process release hydrogen and heat. They are considered as suitable hydrogen donors. Ukraine experts use the alloys LiB2 and LiB10 as hydrogen donor, and achieved good effect, but this kind of material is expensive and hard to store. Aluminum is a cheap metal with rich reserves, it can react with water and release a large quantity of hydrogen and heat. But in common condition, the surface of aluminum is covered by oxides, this stops the react with water. In this work, we prepared the nano-powder of aluminum with strong activity by method of electrical explosion, and discuss the probability of nano-powder of aluminum used as hydrogen donor. Through studies, we found that the nano-powder of aluminum has good ability of releasing hydrogen, and can keep the good rate of hydrogen evolution in weak acids, and fast release hydrogen. Its product isγ-AlOOH with high specific surface area and honeycomb-like structure, which has an effect of assisted catalytic, can improve the react of aquathermolysis. Therefore nano-powder of aluminum has the potential of using as hydrogen donor, but the effect should be proved by further experiments.In the conditions of 80℃and PH=3, theУК130-УК160 system can Intensely react and release a large quantity of heat and gas. In these conditions nano-powder of aluminum can release a lot of hydrogen. The gases can form pulse in a short time, getting through the microcrack, and with the pulse the hydrogen can spread into the oil layers and completely contact with heavy component.The technology of using self-heating to remove plug in near wellbore area with achievement aquathermolysis is proved successful in foreign country, but the effect to the asphaltene with low content of sulfur in our country should be proved by further experiments. And the effect of nano-powder of aluminum also should be checked in the practical application.