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SHALE GAS RESERVOIRS AND CLASSICAL DILEMMA OF EARTH SCIENTISTS AND PETROLEUM ENGINEERS

PRODUCTION CHARACTERISTICS OF MULTILATERAL AND MULTISTAGE HYDRAULICALLY FRACTURED WELLS OF SHALE GAS FORMATIONS Turgay Ertekin Penn State University International shale Gas conference ankara , turkey february 20-21, 2013.

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SHALE GAS RESERVOIRS AND CLASSICAL DILEMMA OF EARTH SCIENTISTS AND PETROLEUM ENGINEERS

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  1. PRODUCTION CHARACTERISTICS OF MULTILATERAL AND MULTISTAGE HYDRAULICALLY FRACTURED WELLS OF SHALE GAS FORMATIONSTurgay ErtekinPenn State UniversityInternational shale Gas conferenceankara, turkeyfebruary 20-21, 2013

  2. SHALE GAS RESERVOIRS AND CLASSICAL DILEMMA OF EARTH SCIENTISTS AND PETROLEUM ENGINEERS • From a global perspective, unconventional gas resources are vast, but undefined. No systematic evaluation has been carried out on global emerging resources. The magnitude and distribution of worldwide gas resources in unconventional reservoirs has yet to be understood. • WORKFLOW • Working with ill-posed systems • Converting ill-posed systems to well-posed systems • Solving well-posed systems

  3. THE BASIC RELATION FOR RESERVOIR EVALUATION ( ) ( ) q = F Y t M , Y ( ) q t where: : production & pressure characteristics at a future time t Y ( ) F Y M : mathematical fluid flow model , F : domain characteristics : recovery process Y • Basic Approaches: • Deterministic Modeling:M, ,and are all fully known • Stochastic Modeling:M, ,and are partially known

  4. Complexity and changes are the issues facing the industry CHALLENGES • We are operating much more challenging reservoirs • and living in a • much more • challenging • world. • There are many • critical key • components • for unlocking these • challenging gas • reservoirs 1 Flow mechanisms in tight reservoirs ??? 2 Understanding geo-mechanics Numerical representation of the stimulated zone 3 Designing advanced well architectures Liquid rich shale reservoirs Relative permeability characteristics Capillary pressure characteristics

  5. (1) COMPLEXITIES IN COMPOSITIONAL MODELING Calculation of Mixed-Gas Adsorption Isotherms from Pure Component Isotherms: CO2 TOTH C2H6 ALGORITHMS ADSORBED VOLUME ADSORBED VOLUME CH4 UNILAN N2 PRESSURE PRESSURE PURE COMPONENT ISOTHERMS MULTI-COMPONENT ISOTHERM

  6. FREE GAS VAPOR LIQUID ADSORBED GAS COMPLEXITIES IN COMPOSITIONAL MODELING Thermodynamics of Mixed-gas Adsorption is Analogous to Vapor-Liquid Equilibria:

  7. MULTI-COMPONENT ADSORPTION ISOTHERM CONSTRUCTION Real Gas Adsorbate Solution Theory Extended Langmuir Isotherms

  8. IN TIGHT FORMATIONS TWO FLOW FIELDS CONTROL THE GAS FLOW DYNAMICS • POTENTIAL FIELD • MACROSCOPIC - DARCIAN FLOW • CONCENTRATION FIELD • RANDOM MOLECULAR - FICKIAN FLOW p1 r1 p2 r2 r1 =r2 p1 < p2 p1 r1 p2 r2 r1 <r2 p1 < p2

  9. p1 p2 p2 p1 r2 r2 r1 r1 p1 < p2 r1 < r2 MULTI-MECHANISTIC FLOW CONCEPT (a) Incompressible fluid p1 < p2 r1 = r2 (b) Compressible fluid

  10. MULTI-MECHANISTIC FLOW CONCEPT Single-Phase Gas Flow : where Multi-Phase Gas Flow : where FICKIAN MULTI-MECHANISTIC DARCIAN k=0.0001 md k=0.001 md k=0.01 md k=0.1 md k=1 md

  11. (2) NUMERICAL REPRESENTATION OF THE STIMULATED ZONE

  12. COMPUTATIONAL CHALLENGES • Two ANNs have been developed: Equivalency ANN-I • Establishes an equivalency between two different hydraulic fracture representations From transverse fracture representation TO Crushed zone fracture representation

  13. COMPUTATIONAL CHALLENGES • Two ANNs have been developed: Equivalency ANN-II • Establishes an equivalency between two different hydraulic fracture representations From crushed zone fracture representation TO Transverse fracture representation

  14. STIMULATED RESERVOIR VOLUME REPRESENTATION • Crushed Zone Hydraulic Fracture Representation • Transverse Hydraulic Fracture Representation

  15. Reservoir Parameters COMPARISON OF THE SRV APPROACH TO NFFLOW MODEL

  16. HISTORY MATCH Using DISCRETE FRACTURE APPROACH

  17. DISCRETE FRACTURE PRESSURE SURFACES 5 YEARS 25 YEARS 50 YEARS 70 YEARS

  18. HISTORY MATCH USING SRV APPROACH

  19. SRV ZONE PRESSURE SURFACES 25 YEARS 5 YEARS 50 YEARS 70 YEARS

  20. COMPARISON OF HISTORY MATCHES

  21. (3) ADVANCED GEO-STEERING TECHNOLOGY Maximum Reservoir Contact (MRC) Wells

  22. ADVANCED WELL ARCHITECTURES • Multiple Targets – intersect different pay zones • Reduces surface footprint • Reduces pay back period

  23. MAXIMUM RESERVOIR CONTACT(MRC) WELLS (1) Maximum reservoir contact wells have one or more branches (laterals) tied back to a mother wellbore, which conveys fluids to or from surface. (2) Combining the technologies of horizontal/multilateral underbalanced drilling gives operators the means of improving production rates and increasing the percentage of hydrocarbons through greater formation exposure and better reservoir drainage. (3) Overall costs are reduced due to increased rates of penetration, elimination of lost circulation, reduction of stuck pipe, and increased bit life. (4) Advanced geo-steering technology is in control. Saudi Aramco Technology and Innovation

  24. Pressure field after 15 years of production Pressure field after 5 years of production Run 1: Horizontal Single Well Lateral Run 2: Horizontal Single Lateral with 4 Wings at 45o

  25. Pressure field after 5 years of production Pressure field after 15 years of production Run 3: Horizontal Single Lateral with 4 Wings, at 45° and with 8 additional Wings at 45° Run 3a: Horizontal Single Lateral with 4 Wings at 45°and 8 additional Wings at 30°

  26. Pressure field after 5 years of production Pressure field after 15 years of production Run 4: Horizontal Single Lateral with 4 Wings at 45°, 8 Wings at 45° and 16 Wings at 90° Run 5: Horizontal Single Lateral with 4 Wings at 45° and additional 16 Wings at 45°

  27. Pressure field after 5 years of production Pressure field after 15 years of production Run 6: Horizontal Single Lateral with 4 Wings at 90° and 8 Wings at 45° Run 7: Horizontal Single Lateralwith 4 Wings at 90° and 8 Wings at 90°

  28. Pressure field after 5 years of production Pressure field after 15 years of production Frac-1: Fracture Penetration Length 400ft Frac-2:Fracture Penetration Length 850 ft

  29. GAS FLOW RATES (SCF/D) OF ALL ADVANCED WELLBORE STRUCTURE STUDIES

  30. SUMMARY OF NUMERICAL EXPERIMENTS

  31. THE BENEFITS OF MULTILATERAL WELLS (1) Increasing the rate of recovery Multilateral wells are capable of increasing production by three to five times of the horizontal wells by increasing the contact area between the well and the reservoir. (2) Decreasing the drilling expenses Drilling multilateral well increases recovery by three to five times and the drilling cost by 1.5 to 2 times on per foot drilled basis. (3) Decreasing the environmental impact Using a multilateral well decreases environmental impact as the multilateral well needs a single surface borehole instead of many boreholes, to cover the same reservoir contact area, if any other technique is being used. (4) Decreasing the operating costs Using multilateral well effectively accelerates the production and rapidly depletes the reservoir. The operating costs will be reduced as the field life cycle is reduced.

  32. WITHOUT INNOVATION NO TECHNOLOGY IS SUSTAINABLE • It is recognized that the principal barriers to implementing new technologies to respond to today’s concerns are not the cost, lack of benefits or technical risk, but other issues such as the resistance to change. • New technologies and innovations may require changes to established work routines and procedures. • Furthermore, we believe that practitioners are not resisting to specific technologies or proposed technical solutions but to creation of a discontinuity in technology adoption. • However, it is this very same discontinuity which sets our understanding and thinking on a new trajectory in technology adoption, and accordingly, we are confident that the analysis protocols that will be developed will have immediate application opportunities. Resource Base ? Economic and commercial viability Geological knowledge Field project status and feasibility

  33. late to the game THE DILEMMA OF INNOVATION opportunity clarity Aversion to risk often means large organizations forego significant opportunities.

  34. THE ROLE OF R&D IS TO ACCELERATE CLARITY opportunity clarity

  35. Closing Remarks… • Scientific developments and innovative technology will be instrumental in unlocking the major sources of natural trapped in unconventional gas reservoirs, dramatically altering the energy landscape. • The missing knowledge-base needed for these developments can most effectively be developed in academic environments working shoulder to shoulder with the industry. And a Final Comment… • In the 21st Century explorationresearch and development environment, a petroleum engineer/an earth scientists is expected to manage: • Knowledge • Technology • and… • INNOVATION

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