Oil and Gas

Oil and Gas | Production Engineering

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

Course Code: N508
Instructors:  Ray FlumerfeltRobert Hull
Course Outline:  Download
Format and Duration
3 days


Business Impact: This multidiscipline course provides engineers and geoscientists with a set of principles and processes that will enable them to plan, evaluate and subsequently optimize the spacing, stacking and sequencing for wells in multi-well pads in unconventional and tight resource plays. This optimization of wells in participant’s areas of responsibility will enhance value and reduce costs even when criteria set by management and external constraints by land-owners or regulatory bodies are included.

The course will address field development optimization, landing horizontal wells and their sequencing at a high level. Discussions on reservoir engineering, geomechanics, completions and the technologies to evaluate the stimulations are key parts of this course. Besides the basics of field development related to well spacing, the training focuses on specific technologies to better understand the stimulation and its effectiveness. Integrated data sets are used to highlight key understandings of what controls EUR for unconventional wells. A data set working through well landing zone selection will also be utilized.

Beyond understanding key aspects of the reservoir and where to land wells, we will discuss the dynamics of offsetting completions affecting reservoir pressures and stress shadows. Participants will learn how to interpret key reservoir engineering and geoscience data to help control stimulation effectiveness.

Duration and Training Method

This three-day classroom course includes lectures with discussion of case studies, worked examples, hands-on exercises, pre- and post-training self-assessment, and a group exercise.

Instructor Robert Hull is a geoscientist; instructor Ray Flumerfelt is a reservoir engineer.

Course Overview

Participants will learn to:

  1. List and enumerate key variables characterizing an unconventional play.
  2. Assemble and rank key geoscience and engineering data needed prior to and during unconventional field development.
  3. Understand basic economics controlling an optimized field development program, including consideration for “cube” development scenarios.
  4. Understand and plan reservoir target (landing zone) selection as well as basics for an appropriate completion design for a single well.
  5. Understand and explain key variables that affect a completion’s zone of influence.
  6. Understand key factors that affect a multiwell development program and how to avoid negative interactions between wells.
  7. Understand and gauge multiple workflows on how to optimize well spacing between multiple wells.
  8. Employ, illustrate and interpret key datasets to better understand the interaction of the completion with the reservoir as well as with offsetting wells.
  9. Describe and evaluate techniques to both understand and minimize the impact of adjacent well parent child interactions.


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.

            This course is designed for:

            • Integrated project teams that need to understand what affects well production, after an initial well has been drilled on the lease.
            • Junior- to mid-level engineers, geoscientists, petrophysicists and data scientists who are responsible for shale fields development and production.
            • Multidiscipline development teams.
            • Reservoir, completion, drilling, and facilities engineers working on shale development.
            • Field and asset supervisors and managers interested in improving the performance of their unconventional assets.

            Ray Flumerfelt

            Ray Flumerfelt is owner of Dallas-based Digital Reservoir LLC.  In this capacity, Ray and his staff assist various oil and gas companies improve subsurface workflows by leverage modern data technologies.  In addition, Ray regularly provides consulting services and reviews projects for various senior management teams focused on unconventional resource development in the Permian Basin Wolfcamp shale and Neuquin Basin Vaca Muerta shale (Argentina).

            Prior to Digital Reservoir, Ray was Engineering Director in Pioneer Natural Resources’ Permian asset team, where he and his team were responsible for well performance analysis, well spacing strategies, completions design and optimization, and artificial lift design in the Permian Basin Wolfcamp shale.  Prior to this role, Ray held various technical and leadership roles at Pioneer including Manager, Corporate Engineering; Manager, Corporate Reservoir Engineering; and Manager, Permian Reservoir Engineering.  Ray and his team were instrumental in developing many new techniques for analysing rate and pressure transient data in unconventional resources including the understanding of well interference through the application of Chow Group (JPT July 2020).  Ray’s primary technical background is reservoir engineering.  He developed and honed his reservoir engineering skills while working for Shell Oil Company and the prestigious consulting firm, S.A. Holditch and Associates.  At Holditch, Ray provided consulting services in the areas of reservoir simulation, rate and pressure transient analysis, and large-scale field studies.

            Ray’s current areas of research include the application of digital workflows and modern database technologies in the field development of unconventional shale reservoirs.

            Affiliations and Accreditation
            MSc Texas A&M University - Petroleum Engineering
            BS Texas A&M University - Petroleum Engineering

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

            Robert Hull

            Robert Hull is a Geoscience and Innovations Advisor for Geophysical Imaging. Geophysical Imaging provides consulting services to better understand reservoir and completions interactions observed though various technologies with a goal of better optimizing and developing unconventional resources, both domestically and internationally. With his extensive experience in development, exploration, and exploitation geosciences, as well as his background in the geophysics of unconventional shales, he has become a theme lead for the Unconventional Resources Technology Conference (URTeC) in the US. Over the past few years, Hull has been working in Australia as well as other international unconventional projects for best-in-class operators. He is also currently a Geophysical Advisor to Silixa, providing knowledge of reservoir and completions interactions observed though various fiber optic technologies to better understand, optimize, and develop unconventional resources.

            In his various roles, Robert Hull has focused on developing unconventional resources from frontier plays to more mature basins, utilizing seismic, microseismic, geomechanical calibration, and fiber optic systems for hydraulic fracture imaging and mapping. He has extensive presentations and publications on reservoir geophysics, with specializations in microseismic and fiber optics.

            Before starting his own company, he was a Geotechnical Specialist at Pioneer Natural Resources for 19 years.  At Pioneer, Hull worked at the senior level in the Geophysical Technology Group and interpreted significant geophysical datasets to aid in understanding parent-child and well spacing relationships. He has been a leader in 3D seismic, microseismic, geomechanics and fiber optics. He also provided interpretations for the Permian Basin, Barnett Shale, West Africa, and South Africa. Prior to Pioneer, Hull worked as a geophysical specialist for Maxus Energy - YPF- Repsol in the US and Indonesia. He holds a Bachelors in Geology from the University of Rochester and an M.S. in Geosciences from the University of Texas at Dallas. Robert Hull is also a member of SPE, AAPG, and SEG.

            Affiliations and Accreditation
            MSc University of Texas in Dallas - Geosciences
            BA University of Rochester - Geology

            Courses Taught
            N508: Optimizing Development of Unconventional Reservoirs: Well Spacing, Stacking and Sequencing of Wells
            N562: Optimizing Development of Unconventional Reservoirs

            CEU: 2.4 Continuing Education Units
            PDH: 24 Professional Development Hours
            Certificate: Certificate Issued Upon Completion
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