Reservoir Management for Unconventional Oil and Gas Resources

Instructor: Prof. I. Yucel Akkutlu (Texas A&M University, United States)
Language: English
Level: Intermediate
Duration and formats:
Online: 4 live sessions of 4 hours CPD Points: 8
Classroom: 2 days CPD Points: 10

Course Description

The field of reservoir characterization and engineering has been evolving quite fast during the last 10 years. This has been due to increasing interest in the unconventional resources in North America. New tools and analysis techniques have been developed. This course introduces unconventional oil and gas resources as a reservoir to the practicing engineers. The emphasis is on the tight gas/oil formations and organic-rich source rocks, in particular shale.

The course provides in-depth discussions on fluids storage, phase change, and transport for reservoir evaluation and development. New discussions related to nano-confined fluids will be included, new reservoir storage mechanisms as sorbed gas and capillary-condensed fluids will be introduced. Hydrocarbon in-place calculations are presented, including new-pore-scale considerations. A new method is introduced to assess the liquid potential of the source rocks.

Laboratory techniques are discussed for the characterization of unconventional formations. The course will help engineers understand transient flow regimes associated with horizontal wells completed with hydraulic fractures, and analyze the production data using various analytical and simulation methods.

A new production history-matching and optimization method will be introduced using a real shale gas well production data. Field case studies will be introduced to discuss the field development including economic and environmental evaluation of horizontal wells with multi-stage fracturing.

Environmental considerations during the development of an unconventional field will be discussed including issues related to groundwater protection. The need for the utilization of large volumes of water for drilling and hydraulic fracturing will be discussed. Waste water disposal operations in USA and the induced seismicity will be discussed.

The course helps students understand the unconventional reservoir physics and improve their business performance by developing more accurate reservoir models.

Course Objectives

The aim of this course is to:

  1. Assess, characterize and classify unconventional resources;
  2. Predict the petro-physical and geochemical quantities relevant to unconventional resources assessment;
  3. Predict hydrocarbon in-place including gas, wet-gas, condensate and oil windows;
  4. Evaluate the relative accuracies of unconventional reserve estimates;
  5. Perform rate-transient and pressure transient analysis for horizontal wells with hydraulic fractures and predict effective fracture dimensions contributing to production;
  6. Formulate a field development plan for an unconventional resources.

Course Outline

Introduction

  • Unconventional oil and gas resources: Tight gas/oil and source rock (CBM, organic-rich shale) characteristics;
  • Unconventional resources in North America, their oil/gas production trends and reserves;
  • What is shale, and what makes shale a hydrocarbon resource?;
  • Resource-reservoir duality and the concept of reservoir creation.

Fundamentals

  • Source rock burial, diagenesis, catagenesis;
  • Multi-scale pore structure development in source rocks;
  • Effective porosity in unconventional resources;
  • Multi-scale oil/gas storage mechanisms in shale;
  • Occurrences of hydrocarbons in organic and inorganic pore networks in source rocks;
  • Phase change and capillarity in organic nanopores; 
  • Volumetric calculations for shale: gas, wet-gas, condensate and oil; 
  • Material balance calculations for source rocks; 
  • Flow and other mass transport mechanisms for shale gas and oil reservoirs;
  • Stress-dependent shale permeability and its modeling;
  • Flow calculations for shale using Wasaki’s permeability model for organic-rich shale;
  • Multi-phase flow considerations in source rocks.

Reservoir Evaluation and Characterization for Unconventional Resources

  • Routine core analysis;
  • Special core analysis;
  • Organic matter classification: bitumen vs. kerogen;
  • Kerogen type and maturity;
  • Hydrocarbons recovery potential from kerogen;
  • Integration of core-data and log-data:
    • TOC estimation;
    • Free and sorbed-phase fraction analysis;
  • Examples on shale core measurement data and analysis;
  • Exercise on predicting shale gas and shale oil permeability;

Pre-frac Injection Test

  • Pressure fall-off (or DFIT) Test Analysis and Interpretation;
  • Typical pressure transient and its signatures;
  • Breakdown pressure, instantaneous shut-in pressure, fracture closure pressure;
  • Analysis of the pressure fall-off data for flow capacity, leak-off type and presence of fractures;
  • Example calculation of the breakdown pressure;
  • Example calculation of the overburden stress using Eaton’s equation.

Geomechanics

  • Fracture evolution in ductile and brittle formations;
  • Griffith’s theory of brittle rock failure;
  • Laboratory measurements;
  • Stress-strain diagrams;
  • Popular geo-mechanical concepts for stimulation decisions;
  • Example decision making on vertical locations for perforations in cased-cemented hole;
  • Exercise calculation of the four elastic moduli using uniaxial test data.

Transient Flow Regimes and Production Analysis

  • Reservoir flow regimes and flow patterns;
  • Pressure evolution during transient flow;
  • Production rate transient signatures in flow patterns:
  • Vertical wells with hydraulic fracture:
    • Horizontal wells with and without hydraulic fracture;
    • Horizontal well with multiple hydraulic fractures;
    • Production rate transient analysis (RTA) methods;
  • Type-curves:
    • Straight line methods, A√k method;
    • Flow simulation requirements for the unconventional reservoirs;
    • Empirical methods, e.g., Arps, Duong, stretched exponential decline;
  • Total fracture surface area calculation using RTA with dynamic matrix permeability;
  • Workflow for engineering analysis of horizontal wells with hydraulic fractures;
  • Example type-curve analysis.

Unconventional Field Case Studies

  • Single-well fracture interference study using Barnett data;
  • Single well fracture surface area calculations using RTA;
  • History-matching Marcellus shale gas well:
    • Impact of the number of transverse fractures on future recovery;
  • History-matching Eagle Ford shale gas well;
  • History-matching Bakken shale oil well;
  • A shale gas well completion optimization:
    • Procedure of calculating hydraulic fracture economics: NPV, IRR, DROI;
    • Number of fracture stages/clusters;
    • Transverse fracture spacing;
    • Fracture propped-length;
  • A tight gas field case study in Canada.

Participants’ Profile

The course is designed for reservoir engineers and earth scientists who would like to learn the unconventional reservoir engineering concepts, terminology and analysis tools.

Participants should have a geology, geophysics, or petroleum engineering background.

About the Instructor

Yucel Akkutlu is Rob L. Adams ’40 Professor in Petroleum Engineering and William Keeler faculty fellow at Texas A&M University in USA. He is a chemical engineer and received Ph.D. in petroleum engineering from the University of Southern California. He teaches undergraduate and graduate courses in reservoir engineering and petrophysics, and has chaired more than 40 graduate-level committees. His research focuses on characterization and exploitation of unconventional oil and gas resources and on oilfield chemistry with application on IOR/EOR. He has written more than 100 peer-reviewed journal articles and conference proceedings, six book chapters, and has three patents. He is the author of “Nano-confined Petroleum Recovery from Source Rocks,” which will be published in 2020. He has received over $3 million in external research funding from sources such as the Department of Energy and unconventional oil and gas industry. He is a distinguished member of the Society of Petroleum Engineers (SPE). He was executive editor of the SPE Journal 2013-2016. He was 2014- 15 SPE distinguished lecturer. He has received 2017 TAMU-Association of Former Students teaching award, 2016 TAMU-Association of Former Students distinguished achievement award, and 2015 AIME Rossiter W. Raymond memorial award. Akkutlu served in various SPE, EAGE, and NSERC (Canada) committees.