Sand consolidation by chemical treatment using indigenously developed chemicals

Abstract

Sand production with reservoir fluid is a well known problem in many parts of the world. Sand production in a well causes restricted production or complete loss of production due to sanding of well bore. There are several methods of sand control but most of the technologies require heavy hardware and tools thus making the cost of new well very high. Chemical sand consolidation can be an alternative to traditional techniques for poorly consolidated formations.

The present studies are carried out to develop a suitable sand control technique for weakly consolidated oil/gas reservoirs using indigenously developed chemicals. The concept is based on the fact that water soluble polymers/chemicals have a strong tendency to adsorb on the surface of rock, thus binding the loose sand. However, the permeability of the formation is maintained by injecting oil soon after injection of chemicals. In order to develop this technology, a laboratory study was carried out to evaluate the chemicals for sand consolidation under static and dynamic conditions. Both the above studies were carried out on a 20/40 sand and using different combinations of chemicals and catalyst. The treated plug was kept at 80 0C for gelation. The compressive strength of sand pack prepared under static condition was found to be around 239 psi, which is satisfactory for field implementation.

The studies in dynamic condition (simulating reservoir condition) was carried out in steel sand pack holder, filled with 20/40 sand having 3.6 cm diameter and 15.2 cm length. The chemicals were flowed through the sand by gravity followed by oil again to keep the flow path open during gelation at 80 0C. the results of study indicated that a gel solution with 7% catalyst and volume equivalent to about 6% of sand volume could give desired sand consolidation with retention of permeability about 790 md at injection point from initial permeability of 72 Darcy of loose sand.