Encouraging Results With a New Environmentally Acceptable, Oil-Soluble Chemicalfor Sand Consolidation: From Laboratory Experiments to Field Application

摘要

The conceptual idea of chemical sand consolidation is to givethe formation some additional residual strength in order toenhance the maximum sandfree rate (MSFR).Sand production in weakly consolidated reservoirs willoccur when stresses in the well/perforation tunnel walls arelarge enough to disrupt the binding between the individualsand grains. This will generate a plasticised layer of sand inthe near well bore area. The layer will erode by the producedfluid and may be transported to the surface. The rate oferosion will depend on the residual strength of the plastifiedmaterial and the fluid rate.There is field evidence indicating a residual strengthcorresponding to the capillary force in water-wet sand to besufficient in stopping or limiting the sand productionsubstantially. Thus, only a small increase in residual strengthof the plastified sand would make large contribution forenhancing the MSFR. This will have large economicalimplications in fields with wells controlled by MSFR.As the criteria for strength are quite low, search forpotential treatment chemicals could be done in areascompletely different from the traditional chemicals used insand consolidation. Three different chemicals have beeninvestigated and one has been brought further for laboratoryqualification and field use.An important property is that the treatment system is oilsoluble.In contrast to water soluble systems, it will not alterthe relative permeability in the oil bearing zones, therebyreducing the risk of increased skin due to changes insaturation. This oil-soluble system will be beneficial in fieldswith low reservoir pressure. The method is employed bysimple bull-heading and will have a kind of self-divertingproperty. A team of engineers and scientists from different Statoilorganizations were put on the job. New challenges regardinghigh water contamination, wells with difficult placements andzonal coverage, and a complex polymerization mechanism inthe carrier fluid had to be solved. These experiences will bepresented and discussed to gain valuable knowledge for futurechemical sand consolidation operations.In this paper, the experimental data and field applicationswill be presented. In one well, oil production was doubled as aresult of the treatment.