Sedimentation Stability of Oil Well Cements in Directional Wells

Unsuccessful cementing operation can jeopardize the whole well construction process, resulting in further costly and time consuming repair operations. The quality of cementing job is dependent on the cement composition and its properties. Design of cement composition is based on the available geological condition, materials and technical situation at well location. The cement properties like flow-ability and strength properties are tested by laboratory methods before application in field conditions. Study of the slurry sedimentation stability is of great importance especially for construction of directional or horizontal wells. There is no convenient direct method to investigate the sedimentation stability of the cements. In this paper, a laboratory method is presented to assess the stability of the slurry by measuring its free fluid content. Laboratory investigations are expanded to study the effect of different additives (weighting agent, silica sand, silica flour and magnesium oxide) and well inclination angle on the sedimentation stability of the slurries. Results show that additive specific surface area plays a significant role in the stability of the cements and therefore should be measured for every additive precisely.