An Experimental Study on the Reinforcement of Weakly-Consolidated Shallow Formation in Deep Water Using an Epoxy Resin-Based Fluid

Abstract

The mechanical properties of Portland cement differ from the weakly consolidated shallow formation in deep water. This results in undesired abrupt changes in the compressive strength and elastic modulus at the cement-formation interface. In this study, a water-borne epoxy resin was applied as a strengthening material to reinforce the weakly consolidated shallow formation and protect the cement sheath from potential failure. The mechanical properties of the unconsolidated clay were tested, including their changes with increases in the temperature and curing time. In addition, the effects of the seawater, cement slurry alkaline filtrate, and saltwater drilling fluid were evaluated. As confirmed by the results, the strengthening fluid was excellent at reinforcing the unconsolidated clay, with a compressive strength of 2.49 MPa (after curing for 7 days), even at a dosage of 5%. A cement slurry filtrate with a high pH was suitable to produce the required strengthening of the formation, especially its early age strength. It should also be pointed out that the used fluid exhibited good compatibility with the saltwater drilling fluid and seawater behaved well as a diluent for the strengthening fluid.