Use of Plastics in Consolidating Loose Sands in Wells

Abstract

Abstract The physical properties of the materials are listed, together with a shortexplanation of how this material binds the sand grains together withoutmaterially reducing the effective permeability of the sand. The chemical can beused in wells with bottom-hole temperatures ranging from 105?F to more than350'F. A description of the equipment required and the techniques used forapplying these plastics to the wells is included. Introduction Recovering oil and gas from unconsolidated sand formations offers one of themost troublesome of all production problems. These sands generally present noparticular trouble while drilling is in progress, but after the well has beencompleted and a pressure differential has been established across the face ofthe producing zone, the formation begins to "slough," resulting in?sanding up" of the well. The term "sanding up" means thatsufficient volumes of sand have moved into the well bore or casing to cause aserious reduction or complete halt of all flow of oil, water or gas. In rarecases a well may produce only a small amount of sand and still continue to flowor pump, the sand being carried to the surface in the fluid stream. However, insuch instances, the result may be a costly repair bill due to the effect of thesand on surface and pumping equipment. The difficulty of producing petroleum from sands that are loosely cemented haslong been recognized by petroleum engineers but only within the last few yearshas any new approach to the problem been undertaken. This involves the use ofplastics that are capable of bonding the individual sand grains in placewithout materially reducing the effective permeability of a formation. The successful application of plastics for the consolidation of poorly cementedsands is relatively recent but now it is widely used in many of the moredifficult areas on the Gulf Coast of Texas and Louisiana. This relatively new use of plastics in the oil fields has been preceded by muchlaboratory and field research on the use of various chemicals for solvingnumerous well-completion and work-over problems. Plastics now are being usedsuccessfully to control gas-oil and water-oil ratios, in zone isolation, therepair of casing leaks, the elimination of caving in cable tool drilling wellsand in the setting of liners and casing. Sand-consolidating plastics, however, are basically different from all others in that they must not form animpervious seal. Field Practices The approach to the sanding-up problem usually has been the mechanicalobstruction of the movement of the sand grains. T.P. 2147