Potential Usage of Local Weighting Materials in Drilling Fluid a Substitute to Barite

Abstract

Barite has been used to increase the density of drilling fluids (DF) since 1922. However, circumstances and needs are changing: The API has recently introduced a new standard of 4.10 sg barite in recognition of diminishing supplies of readily available barite that meet API's standard minimum density specification of 4.20 sg - high quality barite is running out. The search for new hydrocarbon resources to replace reserves has resulted in more difficult drilling conditions & fluid requirements e.g. deep water, ERD, HPHT etc., where ECD management, sag control&formationdamagemitigationarecriticaltosuccess.Alternative weighting materials (WM) such as manganese tetraoxide, treated micronized barite & cesium formate have been successfully used to handle many of the problems mentioned, but they are expensive & not produced in large volumes[Menzel, Dieter, and Sachtleben Chemie]1. Therefore, their application tends to be restricted. There is, therefore, a need for alternative weighting materials capable of providing better functionality than barite, available in sufficient volumes to meet requirements and be competitively priced. This study considers the feasibility of locally available ore minerals as a weighting agent, suitable for use in drilling and completion fluids, which offers significant advantages in the control of ECD, sag & formation damage. It is denser than barite, available in large volumes and is significantly cheaper than the current , high-end weighting materials. Test results are given showing stable fluids with low plastic viscosity, gel strength and sag. Accordingly, it provides a viable alternative product, intermediate between barite and the more expensive weighting material.