SIDERITE AS A WEIGHTING MATERIAL IN DRILLING MUD

Abstract

Successful petroleum drilling largely depends on the type and quality of mud used in the process. There exist many types of muds, which differ in use and composition. Certain muds are composed of materials that can cause damage to the formation and the bottom-hole. This has resulted in the search for alternatives mud additives or addition of new materials to minimize the damage of the formation and enhance the stability of the wellbore. Several bodies of literature exist that research different sources of mud functions and additives, also their effect on the drilling process, the production zone and the environment. Density is one of the main properties of drilling mud because it is the responsible in controlling the formations pressure. So, many weighting agents exist to increase the density of drilling mud. Barite (BaSO4) has a specific gravity of 4.2–4.5 and hardness 2.5-3.5. It has been the most common weight material used in drilling fluids, it is preferred to other weighting materials because of its low cost and high purity but its main disadvantage that its composed of large amount of insoluble acid which damage the formation due to the invasion of the solids into the production zone. A new weighting agent that can be used instead of barite would be a new innovation in the oil field. Siderite (FeCO3) is a weighting material which has a specific gravity of 3.9 and a hardness of 3.5 and makes the mud weighted up to 20 lb/ gal. It is specified by a high acid solubility which didn’t cause damage to the formation compared to barite. So, it can be used as an alternative weighting material in both oil and water muds due to its high specific gravity and high acid solubility.