Research Of Heavy Oil Oxidation Characteristic And Ignition Parameter During In-situ Combustion

Most heavy oil reservoirs have been into the later stage of steam huff and puff,and in-situ combustion is an effective way to enhance oil recovery.The article researched the oxidation process of in-situ combustion,and it is helpful to design the ignition power and control the process dynamically.The article reviewed the experimental research status for in-situ combustion,described the chemical reactions and contrasted the advantages and disadvantages of different method to solve the reaction kinetics equation.The experimental oil is from Du 66 block,and low-temperature oxidation and high-temperature oxidation experiments were conducted to calculate the kinetic parameters,then the influencing factors for oxidation reaction were analyzed.Then the thermo-gravimetric experiment were conducted to analyze the oxidation activating mechanism,and the oxidation process is described in detail by combining the multi-peaks shape of TG curve with heavy oil's oxidation theory,finally four stages of weight loss corresponding to earlier LTO(low temperature oxidation),later LTO,fuel deposition and HTO(high temperature oxidation)were identified,and the demarcation points were clearly defined.Then we realized that layer will accumulate heat during the stage of low-temperature oxidation,and coking zone will be formed after oil cracked,and the ignition will be completed when coking zone combusted.At last,the oxidation transition criteria were analyzed by combining chemical thermodynamics theory and laboratory ignition experiment,and the design method of electrical parameters was raised.When the heat released by igniter or low-temperature oxidation can meet the demand of heat loss of interlayer,heat absorption of layer and fluid and the activation energy of oxidation reaction,then ignition will be succeed and oxidation will reach the stage of high-temperature easily.