TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractBarite has been used as the primary weighting agent in the drilling fluids industry for many years. However, world reserves of barite are decreasing both in quality and quantity while international demand for mud densifiers is increasing. Drilling fluid products need to be high quality with low formation damage and environmentally friendly. Because of these considerations, Petróleos de Venezuela (PDVSA), Venezuelan Oil Holding Company and a hematite supplier initiated a project to search for alternative drilling fluid weighting agents. A product that is mainly composed of high specific gravity hematite was selected after evaluation, laboratory testing and field trials. For this paper, the densifier will be referred to as the new hematite. Commercially, the new hematite has been named ORIMATITA®The main results of the project are:Through investigating natural deposits in Venezuela, a large commercially available deposit was discovered.Similarities between barite and hematite are seen in lab testing that simulated field conditions of rheology, filtration and the stability of oil-base and water-base muds.The abrasive effects on down-hole motors and the wear of metallic and non-metallic materials of surface equipment were extensively evaluated and solutions to potential problems are discussed.Environmental issues have been evaluated and specific procedures are recommended.Field trial results show that the primary advantages of using the new hematite weight material are increased rate of penetration, formation damage reduction, gauge hole, better cement jobs and less environmental impact compared with similar wells using muds containing barite.

This paper was prepared for presentation at the 1999 SPE Latin American and Caribbean Petroleum Engineering Conference held in Caracas, Venezuela, 21–23 April 1999.