The Wolfcamp D is a prolific target within the Midland Basin due to its lateral extent and positive economic returns. Wolfcamp D specific hazards continue to be notoriously costly for drilling operations due to increased borehole instability, bit balling, and the resulting challenges for running casing to total depth (TD). In this paper, a geomechanically validated facies model workflow in conjunction with geomodelling, DFIT (diagnostic fracture injection test), and field-based observations will be presented to avoid formation-induced drilling problems. Instituting a geomechanics facies-based tool is quantitative and repeatable for target delineation. Operator implementation of this approach is both robust and economically feasible.
Implementing a wellbore stability geomechanical target selection tool integrates drilling engineering, geomodelling, geology and petrophysics to deliver a grounded drilling facies solution. The combination of wireline log measurements, drilling field data, and DFIT tests can be merged to determine Wolfcamp D in-situ stress state. In-situ stress state is then analyzed for hazards identified by low compressive and shear-strength rocks. Resulting rock-stress facies are validated with a petrophysical mineralogy model. The stress-based results are combined with spectral gamma-ray clay speciation to determine optimal or suboptimal drilling facies. Resulting facies are modeled in software suites to provide geoscientists and drilling engineers hazard-devoid drilling windows.
Execution of this geomechanics and clay facies-based workflow has resulted in decreased drilling cost by avoiding facies-validated hazards that manifest in sidetracks, tight hole, pack-off, and avoidable bit trips. Application of the facies model is primarily conducted with geosteering to stay within a hazard-limited target and drilling window. Combining this facies-based workflow with a geosteering platform allows the operations team to proactively make decisions for mud-weight, mud properties, and window span prior to well spud. Targeted implementation of a geomechanics and clay speciated workflow has decreased operator development challenges and increased Midland Basin Wolfcamp D target economics in Midland, Glasscock, and Martin Counties.
Early adoption of a geomechanics based target selection approach in conjunction with a drilling engineering team that prioritizes rock mechanics has led to decreased wellbore failures. Applying a facies-based geomodel that incorporates rock geomechanics and clay hazards creates an analytically based solution for determining drilling window span. As a result, the shared understanding between the needs of the geoscience and drilling teams delivers an increased operational solidarity resulting in improved economics and cross-disciplinary operational execution.
