Sand Production Prediction And Sand Control Method Optimization For WM Oilfield

Sand production is a serious problem widely existing in oil/gas production.Most of the China offshore oilfield belongs to unconsolidated sandstone reservoir,in which there exist various degrees of sand production from existing operational wells.The problems resulting from sand production include abrasion of downhole tubular/casing,subsurface safety valves and surface equipment;casing buckling,failure of casing and liners from removal of surrounding formation;and loss of production caused by sand bridging in tubing and/or production flow lines.Scientific and efficient prediction of the sand production tendency is of great significance to guide the efficient development of oil field.There are several methods for predicting sand production.The methods include use of well logs,laboratory testing,use of production data,acoustic,and intrusive sand monitoring devices.The methodologies are reviewed and data needed for predicting sand production are enumerated.Generally sand prediction methods and/or studies of sand prediction are typically categorized into three main types: physical experimentation,semi-analytical/ empirical interpretation of field data,and analytical and numerical modeling.Method used in this paper is purely empirical technique it involves acoustic wave interpretation,calculation of shear modulus,bulk modulus,to determine sand index;by composite modulus and schlumberger method to predict qualitative sand production.According to Acoustic method and composite modulus methods indicate that the WM oilfield reservoir is non-consolidated sandstone that is predicted to be prone to sand production.This paper has studied the formation rock mechanical parameter and its original insitu stress from the log derived data and rock samples from WM oilfield to predict both qualitative and quantitative reservoir sand production condition,however all the necessary factors associated with change in rock strength parameters and insitu stress changes were considered these includes;water production and reservoir pressure depletion due to hydrocarbon production.Moreover,in this paper estimation of critical drawdown pressure for sand production using different rock failure criterions(Mohr-coulomb,Druker-Prager criterion,Hoek and Brown criterion and Mogi coulomb criterion)have been discussed and compared.In the end the Mogi coulomb failure criterion was employed to determine the maximum sand free drawdown pressure.By forecasting the drawdown associated with sanding the best production plan to avoid sand production can be achieved.Furthermore,a thoroughly PSD and clay mineralogy analysis found that the reservoir rock of WM formation is characterized to have fine to medium sized unconsolidated sandstone conglomerate,with content of clay minerals about 6% average,dominated by kaolinite up to 54%,a non-swelling clay type.Also in this work also focused on justifying the suggestion made in the Oilfield Development Plan(ODP)and sand control strategy.The ODP lack necessary information to make a scientific judgment regarding whether or not sand control is needed and what type of control method should be employed.Unlike the ODP this research has pointed out that all four wells have high risk of producing sand,and therefore the optimum sand control method have been designed and recommended for these wells.This thesis discovered that the sand control strategy suggested by the Oilfield Development Plan is not correct,therefore future work for development in this oilfield need to incorporate a thoroughly sand prediction study,and the study should incorporate experimental,empirical and analytical approaches to predict sand production tendency.