Tim Carr - West Virginia University
Elements Source Rock Migration Route Reservoir Rock Seal Rock Trap Processes Generation Migration Accumulation Preservation 2
Reservoir Porous & Permeable Rock Suitable for Production Most Commonly Sandstone & Carbonate What is the Volume of Hydrocarbons? Percentage of Pores versus Matrix Percentage of Pore Occupied by Hydrocarbons Hydrocarbon Saturation What is the Production Rate? Permeability Ease of Flow What is the Geometry of the Reservoir? Internal Geometry - Sweep External Geometry More Hydrocarbons in Vicinity Can We Provide Input to Models of the Reservoir? Static Geomodel Dynamic Fluid Flow Model Field Management & Enhancement A Container From Which Oil & Gas Can Be Produced 3
Primary (original) Secondary (induced) (Generally more complex than primary porosity) 4
Additional open space developed after sedimentation: Cementation Dissolution Dolomitization Fracturing 5
Sandstone Comp. Framework Matrix Cement Pores POROSITY IN SANDSTONE 1. Primary and secondary matrix porosity system 2. Fracture porosity system FRACTURE DISSOLUTION PORE PORE CEMENT FRAMEWORK (QUARTZ) MATRIX FRAMEWORK (FELDSPAR) Note different use of matrix by geologists and engineers 0.25 mm 6
MORE POROUS LESS POROUS 7
Ohio Outcrop 8
Gloades Corner Reservoir, NY 9
Photo: J. Olson, UT Austin 10
11
Photo: J. Olson, UT Austin 12
Photo: J. Olson, UT Austin 13
Photo: J. Olson, UT Austin 14
Example of Fractured Carbonate Reservoir MISSISSIPPIAN LOWER MIDDLE UPPER Greenbrier Limestone Greenbrier Limestone AGE Southeast West Virginia West Virginia Subsurface Northern West Virg Bluefield Maxton Sandstone Mauch Chunk Formation Reynolds Little Lime Formation Lillydale Pencil Cave Shale Reyno Mem Lillyd Memb Alderson Union primary fault play target Big Lime Upp Memb Pickaway Taggard Keener SS Unnamed Sandst Denmar Big Injun Loyalha Mem Hillsdale McCrady Maccrady Formation Fm (Smosna, 1996) (Gas Atlas) Pocono Formation 15 Pocono Formation
study area Isopach of Union Oolite, Rhodell Field Area (from Gas Atlas) 16
CORE PLUG Sparks and Ayers, unpublished 17
ooids scale in cm 3527
3527 intragranular porosity (blue) 1 mm
3527 sparry calcite (poor porosity) oolite rim (8% porosity)
2000 Estimated Ultimate Recovery (EUR) Map C.I. = 200 MMcf Scale: 2000 21
2000 UNION OOLITE NET PAY ISOPACH Porosity > 4% C.I. = 4 #5834 #5638 Scale: 2000 22
2000 500 Cross-Section A A NW SE A A 0-500 -1000-1500 PILOT KNOB LITTLE LIME UNION PICKAWAY DENMAR PRICE ARISTA Scale: 500 A A 23 2000
DEPI #5834 (047-055-00238) UNION OOLITE (Hanging wall) OPEN FRACTURES 30 MMcf natural PILOT KNOB THRUST FAULT 206 OFFSET 50 UNION OOLITE (Foot wall) 24
DEPI #5834 047-055-00238 FMI LOG open fracture drilling induced fractures
DEPI #5834 (047-055-00238) SIDEWALL CORES PILOT KNOB THRUST FAULT 206 OFFSET 50 26
OPEN FRACTURES DEPI #5834 (FAULT ZONE) Highly deformed interval Strike: NNE SSW Dips: 30-50 27
open fracture scale in cm 3446.5 28
3446.5 open fracture 300μm micritized ooids
3446.5 open fracture authigenic, euhedral quartz crystals
calcite filled vugs & fractures scale in cm 3477 31
UNION OOLITE THRUST MODEL WITH FRACTURE SWARM UNION OOLITE (after Nelson, 2001) no scale 32
FAULT WELL PRODUCTION (outside Oolite trend) DEPI #5834 (047-055-00238) Avg Mcf/d (30 MMcf natural) 450 400 350 300 250 200 150 100 50 0 Steep initial decline (fracture production) Lesser decline (reservoir production) 11/5/01 5/24/02 12/10/02 6/28/03 1/14/04 8/1/04 33
How should we manage the field so as to maximize our investments? Can we monitor how oil is being swept out of the reservoir? What about injection wells and enhanced recovery? Is there more oil in the vicinity either at deeper depths or in nearby traps? Can we contribute to a computer model of the field that matches existing production data? If so, we can test future recovery with different drilling scenarios. 34
Add reserves (volumes) New discoveries More from discovered producing zones Additional producing zones Get the most reserves at the lowest cost Invest in the right basins Drill in the optimum locations Correctly assess what can be recovered Avoid unnecessary wells 35
Modified from ExxonMobil 36
Oil Production Geologic Model HISTORY MATCH Actual in Blue Modeled in Red Production Time Reservoir Simulation Courtesy of ExxonMobil 37
An integration of all geologic, geophysical, petrophysical and interpreted or conceptual information about a reservoir into a single 3D numerical description of that reservoir Stratigraphic Interpretation Geophysical Interpretation Petrophysical Interpretation Courtesy of ExxonMobil Structural Interpretation 38
1m Courtesy of ExxonMobil Each cell can be populated with rock & fluid Properties: Facies Porosity Permeability Fluid Saturation Etc. 39
Oil Rate Oil Rate Oil Rate Oil Rate Oil Rate History History Prediction Prediction Actual Modeled Infill Drilling Base Case EOR Base Case Infill Drilling EOR Time Time (yrs) Time Time Time (yrs) Time How do we use this information? Field development planning Field production optimization Reservoir surveillance Courtesy of ExxonMobil 40
Matrix Permeability Fracture Permeability 41
Matrix Permeability Fracture Permeability Distributed Fracture Network 42
Take Home Ideas Secondary Porosity Importance of Fracture Porosity Permeability Ease of Flow Through a Rock Related to Size of Pore and Pore Throats Absolute and Relative Permeability Volume of Hydrocarbons and Rate of Flow of Hydrocarbons Determines Economic Potential Reservoir Simulation Develop Static Geomodel Assist in Maximizing Profit 43
Assignments Reading for this week Exploring for Oil and Gas Traps p. 17-22 & 38-43 Read Today in Energy for Tuesday (2/24) at http://www.eia.gov/ Be Prepared to Discuss in Class - Wednesday Discussion Leader Alexis Johnson Test on Friday 2/27 During Class Multiple Choice, True/False, Short Essays 44