| From September 1998 to April 2016,there are 44 oil wells and 11 wells in Lu2 oilfield.Underground deficit is 66.59×104m3;Cumulative oil production is 65.64×104t;Comprehensive moisture content is 84.93%;Degree of recovery is 6.67%OOIP.In Water injection development process,water storage rate decreased gradually,water consumption rate increased gradually,the relation curve between water cut and recovery is seriously deviated from the theoretical curve.The waterflood development effect of Lu2 is poor.In order to achieve the purpose of stabilizing oil and water and greatly improving the final recovery of oil field,an EOR method must be found for the reservoir characteristics of Lu2 heavy oil field.The experimental of foam EOR for Lu2 oilfield has been studied.First,the primary screening and foam performance evaluation has been studied for 36 kinds of industrial foaming agent in oilfield temperature and atmospheric pressure.Foam performance includes foaming capacity,foam stability,foam composite index,interfacial tension and the compatibility of foaming agent and formation water,etc.Then,the influence factors including effective concentration,mineralization degree and pressure have been researched for foam parameters of XHY-6D?Effective concentration is 0.10%.?.Then,the factors including effective concentration,gasliquid ratio,seepage velocity,permeability,pressure and oil saturation have been studied by single tube core displacement test for form's plugging ability in porous medium.Finally,the influence of slug size and permeability ratio for foam flooding effect has been researched by double tube core displacement test.The results of foaming agent's performance evaluation show that foaming agent's?XHY-6D?suitable effective concentration is 0.10%,and the performance evaluation of foaming agent is 0.001%.Foam system has good salt resistance?The salinity increased from 800mg/L to 174314mg/L,and the foam composite index decreased from 110.81×104mL·s to 66.60×104mL·s,decline of only 39.9%.?.The effect of pressure increase on the foam system parameters.The static adsorption capacity of XHY-6D is 0.26mg/g under the condition of Solid liquid ratio 1.0:1.0 and mineralization degree 86072mg/L.The foaming agent's effective concentration?0.10%?,Gas-liquid ratio?1.0:1.0?and linear velocity?1.0m/d?have been identified by double tube core displacement test.Results show,the foam resistance factor is 66.3 under the conditions of permeability(193.0×10-3?m2),gas-liquid ratio?1.0:1.0?,linear velocity?1.0m/d?,effective concentration of XHY-6D?0.10%?,foam slug?0.3PV?and temperature?65 ??.With the increase of permeability,the foam resistance factor increases first and then decreases,and the permeability of 1065.5×10-3?m2 is the demarcation point?The resistance factor is 121.3?.When the oil saturation is less than 22%,foam system can effectively generate foam and has good stability and strong sealing ability.When oil saturation is between 32% 60% range,although a lot of foam is fractured,but the resistance factor is still maintained at about 20,and has a certain plugging capacity.The increase of pressure has a gain effect on the resistance factor of foam system.The results of the double tube displacement test show that the enhanced oil recovery of double tube core displacement test increase gradually with the increase of foam slug.And the enhanced oil recoverys of double tube core displacement test are 3.23%,7.26%,10.82% and 12.35% respectively,when the foam slug size is 0.1PV,0.2PV,0.3PV and 0.4PV.The enhanced oil recovery of double tube core displacement test increase gradually with the increase of permeability ratio.And the enhanced oil recoverys of double tube core displacement test are 10.82%,13.52%,11.52% and 10.29% respectively,when the permeability ratio is 2.1,4.2,7.3 and 10.3.The foam EOR parameters for Lu2 oilfield,Which are identified eventually by laboratory test,are 0.10%?effective concentration of foaming agent XHY-6D?,1.0:1.0?gas liquid ratio?,1.0m/d?linear velocity?and 0.3PV?foam slug size?. |
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