The Use of Galena as Weighting Material in Drilling Mud

Abstract

A successful oil well drilling depends largely on a good mud Program. During drilling, mud provides sufficient hydrostatic pressure, removes drill cuttings and cools drill bits. Mud additives are always required to provide sufficient hydrostatic pressure to ensure borehole stability. Barium Sulphate (BaSO4) also known as barite is the prevalent weighting material but there is need to develop local materials to augment the use of Barite. This study was aimed at assessing the suitability of galena, a lead sulfide (PbS), as an alternative weighting material in drilling fluids. Two mud samples A and B were prepared which comprised fresh water, caustic soda, bentonite and weighting material. The weighting materials were added to the mud separately to form the required mud weight ranges between 9.0 ppg and 15.0 ppg. Sample A was water-based mud with commercial barite while Sample B was water-based mud with local galena. These samples were analyzed and the density, rheological properties and solid contents were investigated. At 9.0 ppg, the yield point of galena was 20.0 lb/100ft2 and barite 22.0 lb/100ft2 while the 10 second gel strength of galena was 5.0 lb/100ft2 and 8.0 lb/100ft2 for barite. Similarly, little difference was observed in plastic and apparent viscosities. At 9.0 ppg, the plastic and apparent viscosities of galena was 13.0 cp and 23.0 cp while barite was 10.0 cp and 20.0 cp. The result show that galena mud sample gave a little higher yield point and gel strength than barite mud sample. Therefore, galena has the potential to be used as weighting material in drilling mud in place of Barite thereby enhancing the local content initiative of the government. When Galena is sourced locally and used it will reduce overall mud and drilling costs.