An Investigation of the Factors Affecting Barite Sagging Related to Drilling Fluid Properties
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abstract
When drilling for oil and gas, drilling fluid properties are widely studied in order to have an efficient and safe drilling operation. Careful monitoring and modification of drilling fluid characteristics are done on a regular basis to ensure the safety and efficiency of the drilling process. Barite (BaSO4) is a dense mineral with a specific gravity of 4.2 g/cm3 that is considered one of the most important weighing agents for drilling fluids. A common problem faced by drilling engineers in the field is with regards to barite separating from the liquid phase of the drilling fluid and settling down. This issue known as barite sag is very common during static conditions but can also be observed with dynamic drilling conditions. Barite sag can lead to a lot of major drilling and well control issues including a large variation in the drilling fluid density. Problems ranging from lost circulation, well bore instability, well-control difficulties and stuck pipes are just a few. In conventional or vertical wells, higher density drilling fluids settle to the bottom leaving the lower density fluid on the upper portion of the well. However, in a deviated well this phenomenon results from the gravitationally induced settling of the barite to form either a density gradient or a barite sedimentation bed. Reduction in the drilling fluid density as a result of barite sag has the potential of causing severe well control issues which if not controlled properly can end up in disastrous blowouts with potential harm to human lives, property and the environment. Therefore barite sag is a problem that cannot be neglected and any advancement in studying this phenomena is a step forward in solving this major issue. The aim of this study is to formulate different types of mud as well as to study the different properties of each mud. The result will be crucial as it will greatly reflect in deciding the type of drilling fluids to be used in the field. Upon completion of this research, the data obtained will be great for fluid engineers looking to learn about barite sag in order to get significant savings in drilling projects as well as to ensure safety of the personnel involved in the actual drilling. Different types of mud will be formulated. Then, mud properties such as, rheology, density, solids content, particle size, particle size distribution will be measured, compared, and studied.
