N508 Optimizing Development of Unconventional Reservoirs: Well Spacing, Stacking and Sequencing of Wells

Daily Agenda

Day 1:

• Course introduction
• Course objectives and agenda.
• Participant introductions and learning goals.
• Brief introduction on issues with examples of too tight a well spacing
  • Well Spacing Drivers - Economics and Spacing: capturing the maximum recovery factor for the lease, maximizing EUR for the well while minimizing costs for a program with varying commodity prices and costs occurring during the project.
  • Understanding the issue of too tight a well spacing - Type curves – for single vs. pad completions at various spacings.
  • Economics – optimization of the correct well spacing.
• Reservoir characterization overview – Introduction to Unconventional Reservoir Characteristics
• Description of typical shale reservoir.
• Geology – typically deeper marine slow-rate sedimentation, low-energy environment, limited oxidation; horizontally variable over tens of miles. Sediment flux at basin margins etc. (Eagle Ford and Wolfcamp examples).
• Porosity and permeability.
• Components of matrix and of porosity.
• Air permeability vs. effective hydrocarbon permeability at in situ stress.
• Pore volume compressibility and stress sensitivity of permeability.
• Excess resistivity.
• Variations in reservoir pressure, oil quality and gas-oil ratio with depth.
• Rock strength: Young’s modulus, Poisson’s ratio, yield strength, toughness, cohesion and friction coefficient, matrix properties vs. bulk properties.
• Vertical heterogeneity and bedding surfaces.
• Presence and roles of natural fractures.
• Fracture orientations, lengths, heights and frequency.
• Degree of cementation.
• Impacts on inter-well connectivity: “planes of weakness”.
• Reservoir characterization case studies
• Barnett: multi-county, laterally extensive single target interval, dry gas grading to oily, moderate overpressure.
• Eagle Ford: multi-county, structurally involved single target interval, dry gas grading to oil, high overpressure.
• Midland Basin: multi-county, multiple target intervals, oil, variable overpressure.
• Other unconventionals, depending on customer needs, would require access to customer data.
• Where do you want to land your well? Landing zone selection – Team problem set to work.

Day 2:

• Project Engineering overview
• Reservoir target selection.
• Well planning considerations.
• Completion planning considerations.
• Facility planning considerations.
• Production data and analysis.
• Economic evaluations.
• Project planning.
• Reservoir target selection and well planning – spacing and stacking
• Completions planning
• Definitions - Sigma 1, 2, and 3, Max Horizontal stress direction,
• Fractures open in min horizontal stress direction, stress magnitude and variation may vary by depth.
• Hydraulic fracture basics, fluids, rate, proppant, pumping, gel, isolation, types (PNP, sliding sleeves) etc.
• What does a HF look like? (Strain mapping examples).
• PKN fracture and design – basic introduction to models. Appropriate designs (stage spacing, state to stage interaction). Poroelastic effects.
• Pad – volumetrics vs distance.
• Establishing an understanding of the distance of the frac perm zone. Effective pressure definition.
• How far out does the pressure disturbance extend beyond the HF?
• Factors affecting variability in the completion along the wellbore: friction, landing zone variations, build up of altered rock during the stimulation with stress shadows, timing of completion between stages, etc. All affect effective fracture network.
• Facility planning considerations
• Benefits of pad development.
• Safety, security, capacity sharing.
• Provision of utility services --> reduced costs.
• Facility design relative to development sequencing.
• Facility utilization vs value of acceleration.
• Production data and analysis
• Decline curves and type curves.
• Parent wells vs child wells.
• Spacing impacts vs completion designs.
• Project planning case study to work as a team.

Day 3:

• Project evaluation and optimization: Ways forward and advanced topics
• Data needs prior to full field development
• Cost of data vs. not having it. Value of information.
• In-house “science”: rocks and fluids, pressure gauges, etc.
• Analogs, offset operators & data trades.
• Society participation and conferences.
• Quantifying frac hits and inter-well communication
• What is a frac hit? What causes it? Are frac hits necessarily bad?
• Frac Hits in offset wells with downhole pressure gauges and fiber optics.
• Integrating data between the Engineer and Geoscientist
• Oil and RA Tracers.
• Geochem fluid typing to a zone.
• Seismic inversion to understand rock properties.
• Microseismic application and evaluation.
• Mapping the drainage zone using MS.
• Depletion zone mapping during a recharge injection into a parent well. Strain mapping from offset well using fiber optics.
• Tiltmeters.
• Production diagnostics (RTA; Chow group).
• Characterization of the Chow Group.
• Hydraulic Fracture Test Site data case study.
• Enhanced oil recovery from shales
• What we know now:
• Reservoir models suggest recovery factor is limited to near hydraulic fracture zone – 10s of cm about conductive pathways.
• Data of COP for Eagle Ford (Raterman et al).
• What we hope for...
• Development planning issues
• What you don’t control (geology, pressure, leak off rate, etc.).
• What you can control (Spacing, Stacking, Sequencing, Completion design).
• Cube development challenges and opportunities (Concho,QEP and other examples).
• Mitigating frac hits.
• Shut-in of offset wells - required timing for some pressure recharge.
• Protection fracs and refracs - recharging offset parent well with fuild/gas.
• Final summary and pulling it all together: reservoir, pressure, spacing, stacking, and sequencing. Re-looking economics again.