Abstract
Brownfields often pose challenges with identifying optimal locations to drill new wells and developing well trajectory that satisfies technical requirements both at the surface and subsurface. The team utilized risk-based technical and economic analysis which enabled high-quality decisions and created significant value within the Korolev field infill project. This important project involved drilling three new production wells in the field after a two decades of hiatus.
At the early concept stage, TengizChevrOil (TCO) Reservoir Management Group (RMG) Wells Factory team collaborated with Facilities Engineering Projects, Land groups and Wells Early Concept teams to identify an available area for three wells surface locations, followed by well trajectory feasibility and optimization exercise. This enabled the conversion of the Korolev Infill project from three single-well pads (SWP) to one multi-well pad (MWP), improving future TCO operations’ efficiency. During the detailed planning stage, cross-functional team identified an opportunity to optimize MWP trajectories. The bottom hole targets were reassessed based on new re-processed seismic to hit the seismic mega amplitudes which resemble natural fracture network enabling a higher productivity of the wells and sustainable future production. In parallel, the well trajectories were designed to mitigate the key geological risks, including missed casing points, increased water production, and wellbore instability under harsh drilling conditions. The team evaluated key uncertainties in reservoir quality, gas-oil-ratio forecast, and borehole conditions to create a simultaneous decision analysis (SDA) model.
The execution phase of the wells has proven the development strategy – all three wells successfully penetrated the reservoir targets (high-fractured zones) and completed as per value based well objectives. All three wells showed reservoir pressures within the predicted ranges, consistent with Korolev field-wide values and high fracture connectivity. Acquired well logs from the logging-while-drilling and wireline tools for proper conformance control liner installation by placing packers and sliding sleeves at the appropriate depth intervals. Additionally, new data helped reducing subsurface uncertainties and improving the reservoir characterization. Through detailed cross-functional evaluation and effective risk management during both planning and execution stages, the team successfully achieved high-priority value-based well objectives. The insights gained from this endeavor will inform future TCO projects.
A probabilistic analysis using an SDA was implemented during the detailed well planning stage to assess the impact of trajectory changes on the Korolev infill project’s economic value. Based on the SDA results the revised trajectories have improved the project’s feasibility over the mitigated subsurface hazards and risks.
