A New Concept of Chemical Sand Consolidation: From Idea and Laboratory Qualification to Field Application

Abstract

Abstract The conceptual idea is to give the porous matrix of the formation some additional residual strength to enhance the maximum sand free rate (MSFR). Sand production in weakly consolidated reservoirs will occur when tensions in the well/perforation tunnel walls are large enough to disrupt the binding between the individual sand grains. This will generate a plasticized layer of sand in the near well bore area. The layer will erode by the produced fluid and be transported to the surface. The rate of erosion will depend on the residual strength of the plasticized zone and of the hydrodynamic forces acting on that particular zone. There is field evidence indicating a residual strength corresponding to the capillary force in water-wet sand to be sufficient in stopping or limiting the sand production substantially. Thus, only a small increase in residual strength of the plasticized sand would make large contribution for enhancing the MSFR. This will have large economical implications in fields with wells controlled by MSFR, and particularly in the decline phase in which the field is well controlled by the well potential. Since the criteria for strength are quite low, search for potential treatment chemicals could be carried out in areas completely different from the traditional chemicals used in sand consolidation. Three different chemical systems have been investigated and one chemical has been brought further for laboratory qualification and field use at a North Sea Field. In order to carry out a full field test, challenges regarding water contamination, long horizontal wells with difficult placement and zonal coverage, and complex polymerization mechanisms in the carrier fluid had to be addressed. Some of these challenges and field experiences will be presented and discussed to gain valuable knowledge for future chemical sand consolidation operations.