MDT
Modular formation dynamics tester
Accurately measure real-time reservoir pressure and permeability and collect high-quality, representative fluid samples.
Minnkota Power partners with SLB for CCS evaluation
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North Dakota, United States, North America, Onshore
Summary
Minnkota Power Cooperative launched Project Tundra with the mission to build one of the world’s largest carbon capture and sequestration (CCS) facilities. Integrated reservoir performance technologies from SLB provided accurate, detailed reservoir characterization data to improve subsurface understanding, aid state and federal permitting, and ensure deep, secure CO2 storage.
Objective
Minnkota Power Cooperative sought to decarbonize operations by retrofitting a power plant to capture and store 90% of the CO2 emissions from either generator at its facility. Quantifying the site’s CO2 injection and storage potential—and obtaining a Class VI injection well permit—would require a suite of specific subsurface reservoir characterization technology and technical expertise. The cooperative partnered with SLB to gather critical measurements and characterize the subsurface for CO2 storage, injectivity, and confinement.
Results
SLB deployed a full suite of petrophysical services, including the CMR-Plus™ combinable magnetic resonance tool, to delineate potential target intervals with high porosity and permeability. The Saturn™ 3D radial probe provided efficient, effective fluid sample collection in the formation's challenging unconsolidated injection interval where fine particles had invaded the formation, plugged pore throats, and created a significant drop in flowing pressure. The InSitu Fluid Analyzer™ real-time downhole fluid analysis system obtained flowline resistivity, fluid density, and live pH measurements.
To define caprock and injection zone boundaries, SLB calibrated a robust mechanical earth model (MEM) with elastic property measurements from Sonic Scanner™ acoustic scanning platform, hard data from the MDT™ modular formation dynamics tester, and images from Quanta Geo™ photorealistic reservoir geology service.
The partnership resulted in a data analysis and modeling workflow that improved subsurface understanding and set the groundwork for future injection wells in terms of storage capacity, injectivity, and operating levels for containment. Minnkota Power Cooperative used these insights to assist with the research and evaluation required to obtain Class VI injection well permitting for the project, which will ensure deep, permanent underground storage of CO2 emissions.
Injection testing performed by SLB matched up really well with the existing well log data. The permeability matched closely with combinable magnetic resonance (CMR) estimates, and MDT data aligned very well with the step-rate injection test (SRT) and pressure falloff (PFO). So good job on log quality.
Consultant, Loudon Technical Services
A calibrated 1D mechanical earth model involves defining the elastic properties, rock strength, pore pressure, and earth stresses for a given wellbore.
Stress testing was also performed at four additional depths to define high-injection pressure limits of containment in formation intervals above and below the injection targets. SLB applied an industry-leading maximum pressure differential of 5,884 psi.
Stress testing employs a dual-inflatable packer module to isolate a 1-m interval of formation and generate a hydraulic fracture by pressuring up the interval. Stress testing was successful with rebounds and flowbacks performed at four station depths within the injection intervals.
To evaluate CO2-resistant casing condition and cement placement, the Isolation Scanner™ cement evaluation service generated a detailed report differentiating areas of good zonal isolation from areas of poor cement coverage within each reservoir layer. This report established a baseline well integrity analysis for the site’s future carbon and storage work.
To further assure CO2 containment, Quanta Geo service captured more than 8,800 ft of highly detailed, core-like microresistivity images. Natural fractures, facies, and other sedimentological and structural features were also clearly identified and correlated with precision and confidence that were previously possible only from core.
