Microscopic Failure Mechanism Of Weakly Consolidated Sandstone And Its Application In Sand Control

Weakly cemented sandstones are widely distributed in various parts of China,and the oil and gas reservoirs in which are an important type of oil and gas reservoir in the shallow blocks of China.Particularly in offshore oil and gas fields,the continental shelf area is rich in organic material brought by the land,alluvial fan delta area tends to have a short sedimentation time,most of the oil and gas reservoirs are shallowly buried,weakly cemented sandstone reservoirs are more abundant.Due to the weakly cemented sandstone glued loose,mainly mud glued,long-term mining conditions,the reservoir is subject to the perturbation of the work system changes,there is often broken sand phenomenon,so the weakly cemented sandstone reservoir,sand prevention has become an important mining issue.In this paper,based on the study of the mechanical properties of weakly solidified sandstones at home and abroad,the study of sand production and the application of sand control,we use the discrete element numerical simulation method to study the damage characteristics of weakly solidified sandstones and the application of sand control.Firstly,the macroscopic parameters of weakly cemented sandstone were calibrated using the discrete element method,and on the basis of indoor experiments,numerical experiments were used to influence the various fine parameters of the parallel cementation model,to establish the general connection of the macroscopic parameters and the general process of parameter calibration,and to solve some detailed problems in the numerical modeling process.Secondly,on the basis of parameter calibration,suitable fine-grained parameters were selected to establish a numerical model to study the uniaxial ring-breaking characteristics of weakly cemented sandstone,the influence of large size sand and gravel on damage was studied,and the damage characteristics of weakly cemented sandstone were summarized.Furthermore,a simulation model of the sand-blocking process was built by combining discrete elements and python on the basis of the sand-blocking characteristics,and the match between the gravel properties and the screen tube flush shell was studied to provide a basis for the sand-blocking design and parameter optimization.Finally,through statistical analysis and experimental validation,the design method of the sand prevention plate and sand blocking accuracy was improved.The research in this paper contributes to a deeper understanding of weakly cemented sandstone and efficient sand prevention for weakly cemented sandstone reservoirs.