Study On Enhanced Oil Recovery By Selective Lateral Flooding In Bottom Water Reservoir

Reservoir T is a high temperature and high salinity bottom water reservoir.Because of the development of natural energy,the coning of bottom water has greatly inhibited the oil production of the well,and also formed a lot of conical oil and attic oil.The remaining oil is concentrated in the interwell and the top low permeability layer,and it is difficult to develop.On the basis of studying oil reservoir development and the division of water cut rising rule,we screened out the selective lateral flooding system,and studied on enhanced oil recovery by selective lateral flooding in high temperature and high salinity bottom water reservoir,which is of great significance for the subsequent development of T reservoir.Using actual production data of T region and linear regression method,the overall water cut rising rule of this region is determined and the water cut rising rule of single well is divided,and the corresponding relation between water cut rising rule and influence factors is summarized.The results show that the overall water cut rising rule of T region is similar to S curve,the water cut rising rule of single well is divided into five types: slow slope,anti-Z,?,high wave and low wave.By analyzing the corresponding relationship between the water cut rising rule of single well and its influencing factors,the water cut rising rule of single well can be judged,and the selective lateral displacement measures for ?well and high wave well can be carried out.Analysis of nitrogen foam flooding mechanism for selective lateral flooding,evaluate performance of nitrogen foam selective lateral flooding system,selection of the foaming agent mass fraction was 0.2%,the foam stabilizer mass fraction was 0.2%,the flooding system has good temperature resistance and salt tolerance.The nitrogen foam flooding system has a strong blocking ability of selective lateral flooding.From the two aspects of the quantitative and qualitative research on selective lateral displacement influence factors,the influence of geological factors,injection parameters and developing method on selective latera flooding effect were studied by single factor analysis.Research shows positive rhythm,good connectivity and strong heterogeneity of stratum has good adaptability in the simulation of selective lateral displacement,optimization of foaming agent mass fraction was 0.2%~0.6%,the ratio of gas to liquid was 1:2~1:1,injection mode is gas-liquid injection simultaneously,the injection production ratio is 1:2~1:1;five spot patterns,low injection and high production,straight well injection and horizontal well production,are conducive to effective selective lateral displacement.The quantitative study by response surface method shows that the significance of formation rhythm,the foaming agent concentration,and the gas liquid ratio to the recovery yield decrease in turn.The selective lateral flooding method is used in conjunction with the common oil and water control measures commonly used in bottom water reservoir,and the effect of increasing production is analyzed by numerical simulation.The results show that the development effect of selective lateral flooding combined with artificial barrier or foam coning control is better than that of artificial barrier alone or foam coning control alone and selective lateral flooding alone.