Characterization of the Drilling Mud Adapted to the Geological Formations of the Agadem Oil Field, Termit basin (Southeastern Niger): Case of the Dibella Well

Abstract

The objective of this study is to characterize the drilling mud adapted to the geological formations of the Agadem oil field (Niger). During the drilling process, the mud is monitored and adjusted regularly according to the instantaneous logging data. Thus, the typologies of drilling mud and their physicochemical and rheological properties at the level of each phase of drilling were determined in the laboratory of the site during the realization of the Dibella well. Two (2) types of mud (Pre-hydrated bentonite (PHB) and polymer) were used during the drilling of the Dibella well. The PHB mud, used from 0 to 800m depth, is characterized by a variable density depending on the lithology, a MARSH viscosity of 60 to 75 seconds and a pH between 8 and 9. The polymer mud, used between 800 and 2680 m, is characterized by an equally variable density, a MARSH viscosity of 55 to 60 seconds, a plastic viscosity of 10 to 20 mPa.S, a yield point between 2 and 10 Pa, an apparent viscosity of 3 to 5 mPa.S, a Gel strenght (G10’’/G10’) of 1 to 4/2 to 10 Pa and a pH, always between 8 and 9. These parameters, which allowed the Dibella drilling to be carried out in an optimal way, can be used as a guide for the realization of new wells in the study area.