Research On Enhancing Recovery By Numerical Modeling Of Nitrogen Injection In Wenxiyi District

Tuha oil fields are low permeability or ultra-low permeability oil fields.It's physical property is complicated and aeolotropism is powerful.Although some valid treatments are took,such as injecting water,but water quality requirement and cost are high,pressure difference is great.This cause casing failure,water well's low availability and some reservoir flooding failure.Moreover,low permeability reservoir's shale content is high,water sensitivity is powerful,this can create unrecoverable damage,this lead most part crude oil left–in-place.Considering the situation,gas drive is fit for low permeability reservoir at the moment,In twentieth Century eighty years later,because the N2's wide source,low price,no corrosion,no pollution and the unique superiority,the nitrogen flooding has became gas drive's new technique and method.Especially for low permeability reservoir and steep structural reservoir,nitrogen flooding has achieved very god results.The price of N2 has become cheap with the development of N2-producing technology since 1980 s,moreover,it's wide source,free of erosion and pollution make it the new technology during the process of injecting gas to enhance oil recovery especially for low-permeability reservoir and steep structural reservoir.To study the feasibility of injecting N2 in Tuha oil field,we have established the main principle of district selection on the basis of the researches on some related laboratory studies and field applications,screened out Wenxiyi district as the optimal district to carry out N2 flood in shengli oilfield according to above principle and choosed the representative oil,gas,water and core samples to carry out systematical laboratory investigation against the geological condition of the selectedThrough the in-house laboratory investigation on the mechanisms of oil displacement about N2 flood,the improvement degree and improvement rule in phase behavior parameter N2 exerting on crude oil,the evaluation of displacement characteristics through N2 flood and the parameter optimization of N2 injection technology we know that tt's feasible to enhance oil recovery of low-permeability reservoir in Tuha oil region by choosing proper reservoir and injection pattern.