Managing Wellbore Stability Challenges for an Optimum Well Delivery; Case Study, Balsam Field, Nile Delta, Egypt

Abstract

AbstractThis paper presents the integration of Geosciences data for three wells which encountered drilling challenges such as differential and mechanical sticking due to geological complexities. It demonstrates the benefits of integrating all available geoscience data in detecting the drilling hazards, delineating the troublesome zones, and offering a complete solution, including drilling best practices and drilling fluids design based on Geological, Sedimentological, Geomechanical and Petrophysical data analysis.A drilling risk assessment was conducted through an analysis of daily drilling reports for the three wells in the field, meanwhile a Post-drill Geomechanical model was constructed for the same wells using all available data.A Petrophysical analysis of the same wells was completed using wireline data to define the major parameters related to drilling risks such as porosity, permeability, facies changes, formation water salinity and shale volume.A Sedimentological analysis utilized the available information from mud logs, image logs, and core data and cuttings descriptions, to correlate drilling risks with certain lithofacies.This case study considers with the geomechanical model of three wells, including their drilling history, stress/pore pressure models, and rock properties. Additional highlights from the image logs are featured, showing anisotropic bedding plane failure, as well as a comparison of the images to the geomechanical model.This case study concludes the risk and a proposed mitigation strategies that could be implemented to limit the risks posed by high overbalance, clay mineralogy, weak bedding planes and permeable sand layers and to minimize instability when drilling vertical and laterals holes in in this area or similarly complex areas.The pressure surveys revealed the presence of both hydrocarbon and water bearing zones. The pressure gradient was 0.14 psi/ft within the hydrocarbon pay zones, whereas a 0.44 psi/ft pressure gradient confirmed the water bearing zones. The same formation pressure data was utilized to calibrate the pore pressure calculations used for the geomechanical model.All Sedimentological and Petrophysical analyses, along with the post-drill Geomechanical analysis, were utilized to define final solutions for optimum well delivery during drilling, completion, and stimulation Phases.Utilizing the analytics of integrated geoscience data such as sedimentology and petrophysics information, along with geomechanical modeling, can help in understanding the subsurface challenges and propose optimal solutions for optimum well delivery avoiding severe tight spots, differential sticking and pack off, in additions of minimizing the formation damages.