Introduction to the Niobrara. Brief Geologic Overview and Impact on Completion Strategy. Outline

Transcription

1 Introduction to the Niobrara Brief Geologic Overview and Impact on Completion Strategy Fracwell LLC Mike Vincent minute summary of 5 hour school Niobrara Chalk Beds, South Dakota, Yankton County Photo Credit: Samuel Calvin, uiowa.edu Outline Development History Geology Variety of Current Completion Strategies Completion Challenges We Must Address 1

2 Niobrara Background History & variety of fields associated with the Nio 1876: Florence Field near Canyon City CO (associated Pierre Shale) Boulder Field. McKenzie #1-21 produced from 1902 to ~2005 (Pierre) Salt Creek Teapot Dome Tow Creek Silo Field Shallow biogenic gas - W KS, W NE, and E CO >3,000 wells DJ Basin (comingle Niobrara, J Sand and Codell) >20,000 active wells Twin Buttes & Shell Creek (13,000 to 15,000 ft deep gas) 2009: EOG s Jake horizontal well, 1750 bopd; 680 bopd month 2 20 to 2000 ft thick. Found at surface to 24,000 ft deep Thermal maturity varies Oil, thermogenic gas, condensate, or biogenic gas We need to be specific when talking about the Niobrara Late Cretaceous, 90 Ma Ron Blakely, Northern Arizona University 2

3 Late Cretaceous, 100 Ma Ron Blakely, Northern Arizona University Oscillating sea levels Critical to understanding Niobrara deposition Finn, USGS, DDS-69-D Sample Strat Column Showing Benches DJ: Wattenberg Field 200 ft thick at 7,000 ft depth Western Colorado >2000 ft thick at 11,000 ft depth Also >1500 ft thick at 2500 ft depth Sonnenberg 2002, CSM 3

4 Relative extent and location plus some recent Niobrara activity Underlying Second White Specks ~ Favel ~ Greenhorn Medicine Hat, First White Specks Bakken Fluid Types & Depth Range Oil, gas/condensate, biogenic gas Surface (outcrop) to 24,000 ft Age equivalent to Mancos Shale At least 60 different operators in Niobrara play Whiting (Cody Shale) True Oil, Barrett Samson, Termo, Cypress, Quicksilver Delta, Laramie, Antero, EnCana Niobrara EOG, Chesapeake, Baytex, Helis, Resolute St Mary, RKI, QEP, Noble, MDU, Rexx, East(Shell), TARC,CHK,MBI(Anadarko) Laramie, EOG, Bonanza Creek, Wellstar DJ Basin: EnCana, EOG, Noble, Slawson, Chesapeake, SM, Anadarko, Pine Ridge, Lario, Carrizo, PDC, Marathon, Voyager, Rubicon, Whiting, Cirque El Paso Pioneer, El Paso, Manzano Age equivalent to Austin Chalk Assured of Bonanzas, Bubbles & Busts across this extensive play Base Map:ArcGIS Examine Outcrops! Next image near Lyons Watney, Kansas Geological Survey 4

5 Examine Outcrops! Photo from the Portland Cement Quarry near Lyons, CO From PTTC/RMAG field trip flyer, Gustason, Deacon Outcrop of A bench. Typically considered a brittle formation, sandwiched between ductile shales Even minor structure can lead to natural fracturing Outcrop of C bench between Boulder and Lyons. AAPG Explorer, Nov 2010, Durham 5

6 Noble Analyst Day June Variation of Reservoir Conditions Kansas 40-50% porosity 0.2 to 3 md. >0.5 md at shallow depths Biogenic gas from thermally immature chalk Wattenberg Four ft thick chalk benches <10% porosity in some areas Fractures mineralized with calcite, quartz, or gypsum <<0.1 md at ft depth Thermogenic gas and condensate Silo Five chalk benches; develop the B, ft thick <6-8% porosity but open vertical natural fissures <0.01 md matrix perm at 7800 ft depth Oil, API, scf/bbl GOR Watney, Kansas Geological Survey and Pollastro 6

7 Variety of Completion Styles Vertical Wells Mostly cemented Nio may be fractured in single or multiple stages (or bypassed) Mostly light crosslinked fluids with modest sand concentrations Horizontal Wells Cemented and Uncemented Mostly multi-stage completions, some non-compartmentalized Some ball activated sleeves, some plug-and-perf Slickwaters, zircs, borates, gelled propane, hybrids. Some acid. Most have received low sand concentrations Predominantly 20/40 sand, some wells with 100 mesh, 40/70, 30/50 Some RCS, mostly 20/40, some 30/50. Some flowback concerns Some ceramics (40/70 IDC, 30/50 IDC&LDC 20/40 LDC, 16/20 LDC) Experimentation with higher proppant concentrations Some refracs Why are refracs necessary in vertical DJ wells? Gas Condensate wells in DJ Basin up to 5 restimulations Initial fracs used low concentrations of sand Pagano, See also for discussion of refrac mechanisms 7

8 Increase in Horizontal Drilling Mid 2012: 40 rigs 8 vertical 15 directional 17 horizontal Tom Bratton, SLB Sample Well & Frac Design EOG- Jake 2-01H, Weld County 3Q TVD, 11,420 MD (11,838 elsewhere) 3800 ft lat Cemented Frac 430 bbl 7.5% HCl, 12,000 bbl treated water, 53,500 bbls gelled water, 495,000 lb 100 mesh sand, 4.6 mmlbs 20/40 sand 1558 bopd max [1770 reported elsewhere], 50,000 bo 1 st 90 days Should we anticipate that horizontal wells will also need to be restimulated? They are being treated with similar strategies as the vertical wells 8

9 Are challenges similar so we may adapt what we learned in the Bakken? [SPE , ] Niobrara vs Bakken Extensive Cretaceous ~100 Ma Multiple Chalk Benches Locally abundant fissures, likely important to productivity 32 to 62 API [crude to condensate] Underpressured to modest overpressure Extensive Devonian/Mississippian ~400 Ma Middle Bakken Dolomite + Three Forks/Sanish Sand Varying significance of fissures 40 API [light oil in USA] Overpressure ( psi/ft) $ 3 - $5 MM/well $ 6 - $10 MM/well Both developed with horizontal wells and transverse fractures Challenge: Limited Intersection between Wellbore and Fracture Horizontal Well with Transversely Intersecting Frac: Enormous fluid velocity and near-wellbore connection is key! See SPE and

10 Challenge: Effective Frac Design Some reservoirs pose challenges to effectively breach and prop through all laminations Failure to breach all laminae? Will I lose this connection due to crushing or embedment of proppant? Narrower aperture plus significantly higher stress in horizontal steps? Woodford Shale Outcrop Our understanding of frac barriers and k v should influence everything from lateral depth to frac fluid type, to implementation Horizontal Wells If fracs were highly conductive vertical planes that penetrated all the pay, it wouldn t matter precisely what depth you land the lateral But it matters! Niobrara, Barnett, Viking, Bakken, Eagle Ford, Marcellus Fracs either: Fail to penetrate all the pay, or Fail to sustain continuity, or Provide inadequate conductivity (large pressure losses), or Certain depths/trajectories better for artificial lift Perhaps it is an artifact of our completion style.do we need competent/brittle rock to accommodate overflushing? 20 10

11 Some Additional Challenges Design issues Role of bentonite layers Degree of proppant embedment Fluid sensitivity Target natural fractures or tectonically quiet areas? Some areas sensitive to overflushing & conductivity Development near urban and residential areas Increased scrutiny regarding completions and wellsite stewardship Water availability In SE Wyoming, may govern development pace Extensive play, lots of history Try to be specific when you talk about the Nio Many different challenges across the play Completion Strategy Brief Summary DJ has been the ultimate poor boy development Infrequent individual well metering Poor understanding of individual flowrates, let alone interval production More than 5000 refracs have been necessary in the DJ Horizontal well completion strategy is equally uninformed Enormous opportunities for improvement Accommodate complex geology and complex frac geometry Improve ability to drain multiple benches Accelerate or eliminate restimulation More durable frac treatments resistant to embedment, overflushing, flowback, and degradation? 11

12 Conventional versus Unconventional Reservoirs Myths and Misunderstandings that hinder Frac Optimization Detailed Rock Mechanics, Fluid Rheology, and Propagation Theory Physics of Fluid Flow Frac Sand mining and QC, Ceramic manufacturing and QC Proppant Types, Characteristics Understanding the differences between sand, resin and ceramic Available Seminars Conductivity Testing Non-Darcy Flow Multiphase Flow Understanding Proppant Crush Testing - Are hot/wet crush tests superior? Other Issues - Embedment, Stress Cyclic, Elevated Temperature Determining Realistic Proppant Conductivity Field Results 200 summarized on SPE ; ~30 in PowerPoint PTA / Well Testing considerations / Effective Frac Lengths Fines Migration & Plugging Significance of Proppant Density, Frac width, sieve distribution upon proppant value Gel Cleanup Lab studies and field examples documenting load recovery Proppant Flowback and Erosive Potential of sand, ceramic, and resin-coated proppants Frac Pack concepts and field studies Zero Stress applications Flow in wellbore annuli or packed perforations Frac Optimization Mike Vincent CBM frac optimization Fracturing Carbonates Where do unpropped fractures work? Horizontal Wells Comparisons with Vertical Fractured Completions Specific Field Results (Pinedale, Kuparuk, Cardium, Wamsutter, Birch Creek, Siberia, Cotton Valley, Vicksburg, Haynesville Lime, UP + Ranger, others) Bakken Horizontal Wells Importance of Frac Intersection with Wellbore Performance under Severe Conditions (Steam, Acid) + Diagenesis Waterfracs/Slickwater Fracturing Frac Geometry What do Fracs Really look like? What errors are we making? 100 mesh sand pros & cons Refracturing Insight Consulting mike@fracwell.com