George E. King SPE GCS 27 October 2011

Transcription

1 Treating Produced Water For Shale Fracs A U S T R A L I A A R G E N T I N A C A N A D A E G Y P T N O R T H S E A U. S. C E N T R A L U. S. G U L F George E. King SPE GCS 27 October 2011

2 Horn River 5000 acres accessed from a 6 acre pad Slide Source Brad Affleck - Apache

3 Starting Point: 21 Billion Gallons Per Year of Produced Water in US O&G Ops. Produced Water is a valuable resource not waste Produced Brine Input Content Varies: Salinity from 30,000 to 150,000 ppm (higher rarely) Iron from 25 to 2000 ppm Barium from 0 to >250 ppm Oil carryover to 300 ppm Bacteria from <1000 cells/ml to 10 9 cells/ml Total Suspended Solids (TSS) of up to 3 to 5000 ppm, 1 to ~210 microns (70 mesh) Water Management Presentation 13 Sept /10/2011 3

4 What is Needed for Slick Brine Water Fracs? Slick Brine Water Frac Salinity: 30,000 to ~50,000 ppm can vary Iron: remove suspended iron and reduce soluble iron to less than 500 ppm for oil zone fracs Barium: reduce to <20 ppm or control scaling Oil Carryover: less than 50 ppm, prefer < 30 ppm. Bacteria to <1000 cells/ml spikes to 10 4 acceptable TSS: less than 500 ppm of 105 micron and larger solids Water Management Presentation 13 Sept /10/2011 4

5 What is Needed for Gelled Brine Water Fracs? Gelled Brine Water Frac Base Fluid Salinity: 30,000 to ~50,000 ppm constant (+/- 5%) Iron: remove suspended iron and reduce soluble iron to less than 100 ppm for oil zone fracs Calcium: match to needs of polymer Barium: reduce to <20 ppm or control scaling Oil Carryover: less than 50 ppm, prefer < 30 ppm. Bacteria to <1000 cells/ml, add residual disinfectant TSS: less than 500 ppm of 105 micron and larger solids Water Management Presentation 13 Sept /10/2011 5

6 Treating Options Examined Basic Separation Desanders Hydrocyclones Flotation Distillation Pond Mechanical vac and distill Chemical Chemical flocculation Settling / Electro Flocculating Chemical precipitation Scale out methods Separators / Skimmers Disinfection Membrane & Filtration Membrane Ro, FO, ED UV Ozone Chlorine dioxide Filters: micro, ultra, nano Lower toxicity methods Water Management Presentation 13 Sept /10/2011 6

7 Equip Preference: established technology, low cost & maintenance Remove Solids Desander removes TSS to spec Remove particles to ~50 microns (100 mesh is 210 to 105 micron) Some iron and oil will leave with particles Remove Bacteria and Oil Ozone or Chlorine-dioxide No residual chemicals :removal of BTEX & oils. No way for bacteria to develop resistance. Needs small amount of residual disinfectant (~Cl) Ion removal (Fe, Ba?, Ca?, ) Dilution with brine or brackish water input when needed. Water Management Presentation 13 Sept /10/2011 7

8 1 st : Remove particles to about 70 microns or less. However: Frac water does not have to be solids free.. Sand (proppant) has 0.5 to >3% smaller than spec particles Gelled fluids have microgels even liquid polymer. Protect large pores & nat. fracs in conventional reservoirs. In shales, it s a different game. Water Management Presentation 13 Sept /10/2011 8

9 2 nd : Bacteria and Oil Reduction Bacteria Alone UV top choice Ozone 2 nd choice Chlorine Dioxide 3 rd choice Glutaraldehyde Quaternary Amines Ultra & nano filtration Membrane Top choices minimize chemicals, maintenance and cost. Oil (Alkanes & BTEX) Hydrocyclone first choice Skimmers in larger oil ppm cases 2 nd choice Ozone & ClO2 Micro and ultra filtration Bacteria & Oil Hydrocyclone with UV or other after treatment. Water Management Presentation 13 Sept /10/2011 9

10 3 rd What else is needed? a lot of questions Ungelled? (slick water frac) Gelled? (linear, hybrid, etc.) Sulfates where Ba or Sr is an issue. Surfactants? Does water recovery really help? Can water retention really be an advantage? Do capillary blocking forces work to keep natural fractures and fissures open? Ion Control Fluid consistency (can it be mixed?) Scale potential? Worth treating? Surfactants? Other Chemicals? Oxygen scavengers? watch biocide and scale inhibitor interactions Water Management Presentation 13 Sept /10/

11 Brine Sources Brine Source Well 30,000 to 50,000 feed stock, low bacteria and acceptable mineral composition. Flow rate (quantity) not always sufficient Produced Water Slip stream of produced water re-injection Produced water for disposal Frac flowback often low preference because of amount of treating required. Bacterial content variable and increasingly high - Returning chemicals (mostly polymer) Often higher salt content Problem ions Barium, Radioactive ions (rare), heavy metals Other treated gray sewage water, acid mine drainage, industrial waste not at this time for most areas. Water Management Presentation 13 Sept /10/

12 Produced and Brine Water Sources Water Descriptor Fresh Brackish Highly Brackish Saline Sea Water Brine Total Dissolved Solids (TDS) in parts per million (ppm) <1000 ppm 1,000 to 5,000 ppm 5,000 to 15,000 ppm 15,000 to 30,000 ppm 30,000 to 40,000 ppm 40,000 to 300,000+ ppm Water can definitely be too dirty Water freshening via Reverse Osmosis, evaporation, nano filtration, etc., is increasingly uneconomic as salt content increases. Water Management Presentation 13 Sept /10/

13 Produced Water as a Resource Closed Loop Fracturing Produced Water is No Longer Waste Best Recycle Water? Moderate salinity, low solids, few chemicals. Keep water streams separate until you know what is needed. Most chemicals are removed in the formation through adsorption, spending, or precipitation. Polymer often returned. How to remove? Bacteria often biocide resistant increases with amount of recycling. Special methods required. Best frac water? Brine from a dedicated brine source formation or large volume water flood with few chemicals Water Management Presentation 13 Sept /10/

14 How it might fit together Water Management Presentation 13 Sept /10/

15 Other Issues H 2 S in water treating extra Quality of brine source well supply and composition Special requirements for chemical addition Pipeline vs. Truck Transport of treated water to alternate storage or well Grouping of well activity to locate treating facilities Remote well treating skid mounted equipment Power requirements. Water Management Presentation 13 Sept /10/

16 Economics and Conclusions Economics vary with: Level of treatment Ownership vs. rental 3 rd party (disposal well charges) Area specific water source quality Frac fluid base water requirements $0.20 to $1.00 / bbl target cost for OPEX (maintenance and Operation) Estimated CAPEX cost $1mm Water Management Presentation 13 Sept /10/

17 Year % OGIP Recovery (OGIP = original gas in place) Shale Technology Drivers Technologies Applied Shale in Development Average gas price $/mmbtu 1980 s 1% Vertical wells, low rate gel fracs Devonian $ s 1.5 to 2% Foam fracs 1 st slick water in shale Devonian $ to 4% High rate slick water fracs Barnett $ to 8% Horizontal well dominant, 2 to 4 fracs Barnett $ to 12% Horiz, 6 to 8 fracs, stimul fracs, water recycle trial Barnett $ to 30% 16+ fracs per well, Petrophysics increases % to 40% Technology to flatten decline curve, feeling pinch for frac water %+ Pad development drains 5000 acres, salt water displacing fresh for fracs Barnett $9- drop Haynesville $4.20 Horn River $4.00 Future project 45-55% Green chemicals, salt water fracs, low disposal volume, reduced truck traffic, pad drilling, electric rigs and pumps Numerous Depends on market Source: King, SPE

18 HRB Water Delivery 67-K Site Lined pit was added in 2011 to allow plant to stay running Additional water source well brought online due to APA water demand Backup fresh water system has been used on all pads so far 18

19 M3/day HRB Water Delivery Water Delivery K 0% 63-K 54% 76-K 97% 34-L 91% d-1-d 97% Plant Online % Fresh Water Pit & 3 rd Source Well In Service 0 Fresh Water Debolt Water 19

20 Conclusions Fracturing with saline water is possible, economic and production results are promising.. Brine source frac water is 0.25% to 50% of fresh water costs in some cases. Cost of treating produced water for fracs is THE major factor target is $0.25 to $0.50 per bbl. There is a balance between water sources and source locations. Emissions and other problems with truck traffic will be a major factor. Using non potable water when possible makes sense and highlights the environmental responsibility that Apache values 20