Customer Challenge
In the pursuit of optimal data acquisition for an appraisal well in the complex mixed-lithology carbonates offshore the Republic of Congo, the operator faced a critical decision. The acquisition of core samples held immense value for determining mineralogy, texture, secondary porosity, permeability, and relative permeabilities. However, budgetary constraints rendered whole core acquisition unfeasible, leaving the logs uncalibrated and producibility poorly understood, much to the disappointment of the management team.
Solution
In the quest for a viable solution, a careful trade-off between information scale, representative elemental volume, and advanced measurement feasibility was reached. The ingenious use of large-volume (1.5″ by 2.5″) and pore-preserving rotary sidewall cores (SWC) emerged as the answer. These SWCs offered the advantage of conducting lab experiments on a single sample, enabling the acquisition of critical information such as geomechanical parameters, Archie parameters, centrifuge Pc & kr for both reservoir and non-reservoir sections. This comprehensive analysis provided key insights faster and at a significantly lower cost than conventional coring.
Outcome & Value Delivery
The implementation of sidewall coring proved to be a success, saving two valuable rig days and nearly $1 million. This cost-effective alternative surpassed conventional cores, eliminating the ambiguity introduced by the depth uncertainty of drill cuttings. Out of the 34 planned core points, an impressive 29 samples were successfully brought to the surface, resulting in an impressive 83% core recovery. The invaluable core data not only facilitated the calibration of a multi-mineral model but also redefined reservoir intervals, boasting a remarkable +10% increase in net reservoir thickness. Furthermore, the use of SWC significantly reduced operational risk when compared to traditional coring methods, cementing its status as the ideal choice for data acquisition in the challenging carbonate environment.
