Conventional Drilling Fluids can cause different problems if used in the final stages of the well operations, to avoid dealing with reservoir skin damage, fluid and solids invasion, clay/shale swelling, new fluid systems such as Reservoir Drill-in Fluids and Completion and Workover Fluids were developed to protect the reservoir and prevent damage.
The aim of this Master Thesis Project was to present the difference between Conventional Fluids Systems and Reservoir Drill-in Fluids and Completion and Workover Fluids. The project incorporates different types of fluids used for the above mentioned operation, properties and functions that these Special Fluids develop under the surface of the Earth in either drilling the reservoir section or completing it.
The data and experience that aided the writer in finishing this project was acquired from rig laboratory testing on Conventional Oil Base Mud System (VersaClean), Oil Base Reservoir Drill-in Fluid (VersaPRO) and two types of Completion Fluids (NaCl brine with densities of 9.4 lb/gal and 10 lb/gal). The results of these tests reflect a real life drilling and completion operations, and can be mentioned that several fluid treatments were performed in order to bring the fluids back in Drilling Program specifications. From the comparison of the four fluids, with a 9 day average for the drilling systems, and one test performed on each of the NaCl Brine systems, the most important results were: Solids: 25% Conventional OBM, 14% RDF; Plastic Viscosity: 29 cP Conventional OBM, 19 cP RDF, 5 cP NaCl Brines; Yield Point: 22 lb/100ft2 Conventional OBM, 14 lb/100ft2 RDF, 2 lb/100ft2 NaCl Brines; Fluid Loss: 2.1 ml/30 min Conventional OBM, 2.4 ml/30 min RDF. Backed by these results, Reservoir Drill-in Fluids and Completion and Workover Fluids are more effective than the Conventional Fluid System when the reservoir section is drilled and completed, and if used can decrease the final cost of the project.