Analysis And Diagnosis Method Of Fire Flooding Effect

Fire flooding is one of the key technologies for heavy oil development.Analysis and diagnosis of fire flooding effect is an important part of fire drive reservoir management.Because the internal reactions of fire flooding determines its production characteristics.It is necessary to combine the internal transformation and combustion mechanism with the production effect to a fully evaluation of fire flooding.Based on indoor experiments and field data,the characteristics of fire flooding are analyzed from the aspects of oil displacement characteristics,composition changes and production changes.The influence of geological factors,crude oil properties and the adjustment of development measures on the effect of fire flooding are studied by numerical simulation.Then,based on the reaction mechanism of heavy oil,the transformation path of oil components in the process of fire flooding is studied.And then combined with the theory of material balance and the law of oil and water percolation,two characteristic curves of gas-liquid and oil-water characteristic of fire drive are derived respectively.Finally,fire flooding effect parameters including oil saturation of oil block,the maximum sweep volume and thickness of oil block are calculated by using the oil-water characteristic curve.It is found that oxidation and thermal reaction are two major reactions of heavy oil for fire flooding.The low temperature oxidation reaction leads to the transformation of oil component into the colloid asphaltum with increasing polarity,and the thermal reaction will transform the heavy oil component into the light component with low molecular and the high aromatic coke.The production of fire flooding is divided into increasing production stage,stable production stage and oxygen breakthrough stage.Before the breakthrough of oxygen,there is a linear relationship between the gas and liquid produced.The characteristic curve of water and oil shows an exponential form on the increasing production stage,and a straight line on the stable production stage.The inflection point of the water-oil curve is related to the maximum sweep volume of fire flooding and the oil saturation of oil block.With a field case effect analysis,the oil saturation of oil block is located between 0.72~0.76.The maximum volume sweep efficiency is 34.5%.And the average thickness of oil block is 56.1m.Once the fire flooding gets to the stable production stage,the comprehensive water cut will stabilize at 0.7.The practical application shows that the component transformation path and the characteristic curve of fireflooding purposed in this paper have certain practicability to analyze the combustion dynamics of the oil layer and improve the development effect of the fire drive.