Optimization Of Process Parameters For Nano Depressurization And Augmented Injection Technology In Extra-low Permeability Reservoir

Due to its deep burial,slim pore throat,poor connectivity and other reasons,problems like water injection pressure increase,water injection quantity below the requirements may easily occur in the process of water flooding in low penetrability reservoir.Under the conditions that conventional injection process(acidizing,fracturing,etc.)cannot solve this outstanding problem,nanometer injection technology is introduced and has made excellent achievements.However,the nanometer injection technology was developed on general low permeability reservoir,the whether its nanometer material performance and optimization of its process parameters are applicable to the extra low permeability reservoir has became an urgent research topic.Therefore,research on nanometer injection technology process parameter optimization for extra low permeability reservoir has very important influence on promotion of nanometer injection technology and the long-term and efficient development of extra-low permeability reservoirs.Based on the research and application results of nanometer injection technology in general low permeability reservoir,nano agent stability and other tests were conducted and a new type of nano-agent suitable for extra-low permeability reservoirs was selected.In consideration of its porosity and permeability and other characteristics in extra-low permeability reservoir,combined with our construction experience,we used the core for displacement test to complete optimization of process parameters.Working plan on Block Shenshi-A was thus drafted and applied to the oil field;and completed the efficiency evaluation.Work and achievements of the research are as follows:(1)Starting from nanometer injection mechanism,the paper analyses the influence of nanometer material performance and process parameters on the efficiency of augmented injection.Grey correlation analysis method is employed on process parameters for weighting analysis,and determines that porosity,permeability,dosage of nano-agent,concentration,treatment time,acid and alkali pretreatment and other factors are the main research parameters for augmented injection technology in extra-low permeability reservoir.(2)Making use of the five types of depressurization and augmented materials provided at the field,comparison tests on absorption ability and others were carried out;and nano-agent stability test was also conducted by using the processed and up-to-standard injection water as dispersant.Finally SL-3 nano-agent was selected for Block Shenshi-A from the aspects of performance,cost,preparation difficulty and so on.(3)On the research results of common low permeability reservoir process parameters,nano-agent dosage,concentration and treatment time displacement tests as well as acid and alkali displacement test were conducted by using the core of extra-low permeability reservoir.Combined with process treating radius,efficient porosity volume,acid base neutralization and construction experience,optimization of augmented injection technology process parameters for extra-low permeability reservoirs was completed.(4)A nanometer augmented injection schedule suitable for Block Shenshi-A extra low permeability reservoir was drafted.Field tests on 3 wells in Block Shishen-A were carried out and excellent augmented injection results were achieved.At the same time,compared with the field application results in general low permeability reservoir,nano augmented injection efficiency evaluation in extra-low permeability reservoir was completed(5)SL-3 water-based nano-agent is suitable for Block Shenshi-A extra-low permeability reservoir,and the onsite construction scheme on optimized process parameters is reasonable and effective.Field tests in 3 wells were all successful and had excellent depressurized and augmented injection effect.