Construction and characteristic analysis of in-situ combustion production dynamic evaluation equation based on seepage difference of zones

The combustion-displacement relationship is complex of in-situ combustion (ISC), making it difficult to assess the combustion effect on the ground. In this work, combined with the characteristics of ISC production stage and oil-gas-water relative permeability relationship, the production dynamic evaluation equations are established, such as cumulative gas-liquid, cumulative oil-water and water cut. The determination method is obtained of oil saturation and gas saturation in the oil bank. It is found that the evaluation equation is exponential in the production rising and oil bank breakthrough stage, which is linear in the stable production stage. The obtained evaluation curves can fully reflect the stage characteristics of ISC. According to the evaluation equation, the oil saturation in the oil bank of the ISC test area in Xinjiang, China is calculated to be between 0.6 and 0.72, the temperature is roughly 110 °C, and the gas saturation is 0.09. The diagnosis believes that the test area has entered the oil bank breakthrough stage in the later stage. The established evaluation equations can directly use the actual production data to diagnose the characteristics of ISC production at different stages, and can quickly provide guidance for the adjustment of field measures.