Study On Improving Polymer Flooding Development And The Analysis Of Economic Effectiveness

Petroleum, which is non-renewable, plays a pivotal role in the national economicdevelopment. The annual production over50millions tons has lasted for27years inDaqing Oilfield, which is a miracle in the development of similar oilfields all aroundthe world. However, how to increase recovery efficiency has become a significantresearch topic with deepening development degree, poor quality of developed targetsand harder development.With a dozen years of industrial production in the polymer flooding in DaqingOilfield, the sophisticated supporting technologies were achieved, and the productionof tertiary recovery, mainly from polymer flooding, accounts for about1/3of Daqingproduction. However, in the late period of the injection-polymer, the mobilizedformation of nearly1/5injection wells concentrates in the high-permeability layers,accounting for less than50%of all oil layers, and with serious polymerinefficient-invalid circulation. Meanwhile, since the amount of oilfield chemicalsincreases year by year, and oil production and increment from a ton of polymer havedecreased annually, which is only1/2of its maximum at present, the requirements oflow cost, high efficiency exploitation could not be met. Therefore, it is necessary tocarry out a study for supporting technology of increasing the efficiency of polymerflooding and for evaluation methods suitable for the development effect andefficiency between polymer flooding blocks.The development effect of the blocks completing polymer flooding was analyzedby laboratory physical simulation, numerical simulation and economic evaluation, toidentify the law for polymer flooding, provide guidance for most timely, effective andpersonalized adjustment in blocks under polymer flooding, scientifically reduce theamount of polymer powder without affecting the oilfield development effect, andfurther improve and complete the technologies for increasing polymer floodingefficiency.The optimized design of polymer injection object, well pattern and combinationof layers were analyzed in this paper. The development objects with similar oil layerproperties were combined and developed with same well pattern to reduce theinter-layer interference, so as to improve ultimate recovery efficiency. Experimentalstudy for the match between polymer molecular weight, concentration and oil layerpermeability were carried out to set up the matching chart and determined thequantitatively functional relation between polymer molecular weight, concentration and oil layer permeability, to provide reliable basis for optimizing the design andadjustment. Through optimization of polymer molecular weight, the matchingbetween injection system and oil layers as well as injection conditions was evidentlyimproved. Meanwhile, the criteria for selecting appropriate well and layer in majoradjustment of each injection stage were established, the multiphase sluggingalternating injection technology were completed, and the quantitative andstandardization board for adjustment including fracturing, separate injection andprofile modification were established and improved to realize detailed following andadjustment and enhanced efficiently the effect of polymer flooding. The methods forbenchmarking, classification, evaluation and staged improving recovery forecastwere established, to form dynamic management for benchmarking, classification,following evaluation and rapid forecast in the process of polymer flooding andprovided timely, effective, personalized guidance for blocks under polymer flooding.