Study On Design Method Of Sand Control In Deep-water Reservoir

With the exploration and development of deep-water oil and gas fields,deep-water oil and gas reservoirs will become the focus of exploration and development in the future.The deep-water gas reservoir has a low degree of compaction,loose cementation,and easy sand production during the production process,and the deep-water gas wellbore has a fast fluid flow rate and a strong sand carrying capacity,which brings about problems such as high sand control difficulty and high operating cost.Sand control failure will have a serious impact on the production of deep-water gas wells.The design of sand control sand retaining precision in deep-water gas wells is directly related to the reliability and long-term effect of sand control.The design of sand retaining precision is too large,which may cause erosion of the screen tube,resulting in sand control failure.If the precision of sand retaining is too small,it will cause blockage and affect the capacity.At present,the commonly used sand retaining precision design method is mainly for onshore or shallow sea oil and gas fields,and has not been fully applied to the deep-water gas wells.Therefore,it is necessary to carry out research on the design method of sand retaining precision that comprehensively considers sand control effect and gas well productivity.The design of sand retaining precision in the sand control process of deep-water gas wells is closely related to the reservoir grain size,while the core cost of the reservoir in the deep-water drilling process is quite high,and the core section is limited and the quantity is small,and the whole particle size distribution of reservoir cannot be obtained completely.so it is especially important to use a small amount of reservoir particle size data for the spatial distribution of the entire reservoir.Therefore,based on the investigation of foreign domestic and literatures,based on the correlation of reservoir physical properties such as reservoir particle size,porosity and permeability,the multivariate regression statistical analysis method was used to establish the mathematical model between the particle size and the pore depth at the corresponding depth of the existing granularity data well.Through this model combined with the pore-permeability data of unknown particle size data wells,the longitudinal distribution of grain size in each well area of the reservoir can be predicted.Then,by analyzing the relationship between reservoir geological sedimentation law and grain size,the lateral distribution law of reservoir grain size is obtained.Through the prediction of the horizontal and vertical distribution law,enough granular data points are obtained,and the Kriging interpolation method in geostatistics is used to spatially distribute the overall particle size of the reservoir,and a new method for reservoir grain size prediction and spatial distribution is established.The application results of the deep-water K gas field show that the target block particle size d₅₀ varies from 59.18 to 250.15?m,UC varies from 2.40 to 4.83,SC varies from 5.23 to 9.01,The sand of the formation sand is better in sorting and the heterogeneity is smaller.Considering the balance of plugging and erosion problems in the moderate sand retaining process of gravel packing.Firstly based on particle packing theory and particle bridging theory,the porosity and pore throat size of gravel layer under different conditions of gravel accumulation are analyzed.The K-C model is used to calculate the corresponding gravel layer permeability,and then the gravel lamination drop characterizing the plugging characteristics is calculated;Through research and analysis of domestic and foreign scholars'research on screen erosion,the Cameron model is used to calculate the erosion rate and erosion life of the screen to characterize the erosion characteristics.The gravel lamination and the erosion rate of the screen are taken as the preferred conditions.The optimal solution and the worst solution index system are constructed from the actual production angle.The optimal design result of the gravel size is selected by the method of the Topsis method.Then the corresponding matching screen is designed and calculated.A design method suitable for deep sand gravel filling and sand control is proposed.The application results of the deep-water K gas field show that in the case of considering blockage and erosion,the gravel size is 0.476mm and the appropriate sand retaining design has a gravel size of 30-40 mesh and the matching sieve precision is 150?m.This method can effectively exert sand control and release productivity.The design of moderate sand and sand control sand in the gas field has guiding significance.