Schlumberger

Performance Report: Bakken Shale: OPTM-IZER Closed Loop Approach Delivers in Zero Discharge Operation

Challenge: Owing to rising disposal costs and tightening environmental restrictions, a Bakken Shale operator requested a proactive solution that would move it closer to a total closed-loop drilling operation. The operator’s past experience with closed-loop systems was costly and inefficient with no transparent value. What’s more, previous conventional attempts were ineffective in handling the considerable volume and size of the cuttings generated during high ROP surface drilling intrinsic of North Dakota’s Bakken Shale. Furthermore, the intermediate and production oil-base mud (OBM) and brine sections, respectively, also raised concerns of high ROP combined with the need to either reduce or increase mud density very quickly to manage the ECD and avoid losses or influxes. Consequently, any closed-loop package design would be required to maintain density and other fluid properties in the water-base mud surface sections, the oil-base mud intermediate sections and the brine-base production interval without having to dilute and dispose of fluids.

Solution: M-I SWACO immediately began to design a client-specific package that would meet the following requirements:

  1. Mobility and timely installation
  2. Winterization / harsh environment functionality
  3. High-capacity dewatering and centrifugation
  4. Spill prevention via an automation/control package
  5. Barite recovery (preferentially removing low-gravity solids (LGS) in weighted systems)
  6. Reduced liquid-on-cuttings (LOC) being discharged into the cuttings pit. This would cut closure costs if no free liquid is present
Upon completion, the M-I SWACO customized OPTM-IZER closed-loop package was mobilized to two of the client’s drilling locations.

Result: The Bakken Shale campaign verified the capacity of the OPTM-IZER ability to provide high-capacity dewatering and solids removal by means of dual fully variable-speed centrifuges, while also allowing for barite recovery and/or conventional barite stripping in the weighted sections. The performance of the system exceeded both internal and external expectations.

  • Zero dilution required on surface
  • Automation package kept pace, regardless of flow rates to the centrifuge packages
  • All fluid was recovered and recycled for future surface holes
  • The OPTM-IZER package in conjunction with the Fluids Management Plan allowed for the processing and treatment of tank-bottom waste from the rig pit cleaning operations during the casing and cementing operations

Well # Bit Size (in/mm) Surface TD (ft/m) Mud Wt. (PPG / SG) Circulation Rate (GPM / LPM)
Confidential 13.5 / 343 1835 / 559 8.7 / 1.04 750 / 2839
Confidential 13.5 / 343 1835 / 559 8.6 / 1.03 750 / 2839
Confidential 13.5 / 343 1835 / 559 8.5 / 1.02 750 / 2839

During the operation, the M-I SWACO design team quickly modified the centrifuge discharge chutes to allow for higher than anticipated solids volume. Consequently, all initial OPTM-IZER designs in the future will incorporate the larger discharge chutes. The Bakken Shale experience validated the OPTM-IZER closed-loop package, in conjunction with additional recovery equipment if required, as efficient and cost-effective solution for zero-discharge drilling.


Download: Bakken Shale: OPTM-IZER Closed Loop Approach Delivers in Zero Discharge Operation (0.51 MB PDF)

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“The mobile OPTM-IZER package effectively demonstrated to our client the effectiveness of a well-designed and operated closed-loop drilling system.”
Mike Kirby
Senior Technical Service Engineer
M-I SWACO