Development of a High Pressure Gas Gun for H 2 S and CO 2 Service

Transcription

1 6 th Annual Sucker Rod Pumping Workshop Wyndham Hotel, Dallas, Texas September 14 17, 2010 Development of a High Pressure Gas Gun for H 2 S and CO 2 Service Norman W. Hein, Jr., P. E. (Oil & Gas Optimization Specialists, Ltd.) James N. McCoy (Echometer) Lynn Rowlan (Echometer)

2 Contents Background NACE MR and ISO Review SSC considerations Major Gas Gun Components Design Materials Conclusions & Recommendations 2010 Sucker Rod Pumping Workshop 2

3 Background Unique high pressure gas gun developed last year Intrinsically safe 5,000 psi service Presented at SWPSC Sucker Rod Pumping Workshop 3

4 5000 psi Gas Gun Ops manual picture 2010 Sucker Rod Pumping Workshop 4

5 Additional Requested Capabilities Some worldwide operators wanted other capabilities Also able to be installed in any hydrogen sulfide (H 2 S) producing environment Also able to be installed in carbon dioxide (CO 2 ) producing service 2010 Sucker Rod Pumping Workshop 5

6 NACE MR0175 Review In 1963, NACE Technical Committee T-1B released 1B163 Recommendations on Materials for Sour Service This included several specs including NACE Spec 150 on Valves In 1968, T-1F released NACE Recommendation 1F166 Sulfide Cracking Resistant Metallic Materials for Valves for Production & Pipeline Service In 1975, original Materials Requirement standard MR0175 released Materials for Valves for Resistance to Sulfide Stress Cracking in Production & Pipeline Service 2010 Sucker Rod Pumping Workshop 6

7 MR0175 cont In 1976, Texas Railroad Commission adopted MR0175 as an equipment requirement; making it more general In 1978 a new version of the standard was released - Sulfide Stress Cracking Resistant Metallic Material for Oilfield Equipment In 1984, s added to Material Issued by NACE Task Group T-1F-1 as Materials Requirement (MR) standard Provided guidelines for selection of materials resistant to failure in H 2 S containing oil and gas environment 2010 Sucker Rod Pumping Workshop 7

8 ISO In the mid-1990s, NACE approached ISO TC 67 to consider adopting MR0175 as an international standard A co-chaired NACE & ISO group was formed with the goal to develop an expanded standard to include all mechanisms of cracking that can be caused by H 2 S: sulfide stress cracking, stress corrosion cracking, hydrogen-induced cracking, step-wise cracking, stress-oriented hydrogen induced cracking, soft zone cracking, and galvanically induced hydrogen stress cracking. Sept , Sucker Rod Pumping Workshop 8

9 ISO cont Also the standard included the effects of ph and temperature on the potential for cracking. The resulting document ISO Petroleum and Natural Gas Industries Materials for Use in H2S- Containing Environments in Oil and Gas Production was re-balloted and accepted by ANSI/NACE and comarked as NACE MR0175/ISO It now supersedes all previous versions of MR0175 NACE MR0175/ISO is in three parts Although Part 1 shows a copyright date of 2001, Parts 2 and 3 were not completed until 2003 So the standard shows a copyright date of Sucker Rod Pumping Workshop 9

10 ISO 15156; now includes: NACE MR0175/ISO Part 1 International Standard General Requirements NACE MR0175/ISO Part 1 Technical Circular 1 NACE MR0175/ISO Part 1 Technical Corrigendum 1 NACE MR0175/ISO Part 2 International Standard Carbon Steels & Low Alloys NACE MR0175/ISO Part 2 Technical Circular 1 NACE MR0175/ISO Part 2 Technical Corrigendum 1 NACE MR0175/ISO Part 3 International Standard CRAs and Other Alloys NACE MR0175/ISO Part 3 Technical Corrigendum 1 NACE MR0175/ISO Part 3 Technical Corrigendum 2 NACE MR0175-ISO Part 3 Technical Circular 1 NACE MR0175-ISO Part 3 Technical Circular Sucker Rod Pumping Workshop 10

11 Sulfide Stress Cracking (SSC) Sulfide stress cracking (SSC) is defined as brittle failure by cracking under the combined action of tensile stress and corrosion in the presence of water and H 2 S. Actually, sulfide stress cracking is a special case of hydrogen embrittlement that occurs when H 2 S dissociates, in the presence of water, into hydrogen and sulfide ions. Diffusion of hydrogen into a metal is catalyzed by the presence of the sulfide ions, promoting hydrogen embrittlement Sucker Rod Pumping Workshop 11

12 SSC Susceptibility - 6 Factors 1. Chemical composition, strength, heat treatment & microstructure of the material; Including certain elements (for example, nickel in steels have been identified as SSC promoter) Within a particular alloy, as strength (and hardness) increase, the susceptibility to sulfide stress cracking increases 2010 Sucker Rod Pumping Workshop 12

13 6 Factors (cont) 2. Hydrogen ion concentration (ph) 3. H 2 S concentration and total pressure (or H 2 S partial pressure) of the process environment 4. Total tensile stress (accounting for both applied and residual stresses) 5. Process temperature 6. Exposure Time 2010 Sucker Rod Pumping Workshop 13

14 SSC Partial Pressure Graph 2010 Sucker Rod Pumping Workshop 14

15 NACE MR0175/ISO Part 1 Application Drilling, well construction & well servicing equipment Wells including subsurface equipment, gas lift equipment, wellhead, and Christmas tree Permitted Exclusions Equipment only exposed to controlled composition drilling fluids Drill bits BOP shear blades Drilling riser systems Wireline & wireline equipment Surface & intermediate casing Sucker rod pumps & sucker rods Electrical submersible pumps Other artificial lift equipment Slips 2010 Sucker Rod Pumping Workshop 15

16 NACE MR0175/ISO Application Flowlines, gathering lines, field facilities, & field processing plants Sour water handling equipment Natural gas treatment plant Permitted Exclusions Crude oil storage & handling facilities operating at gauge pressure below 4.3 bar (~65 psi) 2010 Sucker Rod Pumping Workshop 16

17 Part 1 Applicability A review of the left hand column shows that the gas gun is not specifically listed as being applicable to the requirements. The right hand column shows that there are exclusions, specifically on "other artificial lift equipment" that could be applied. However, a more definitive action would be to fabricate the 5000 p.s.i. gas gun and use acceptable components for the well head system that will comply with this standard. In this way, there is no question that the gun can be certified for H 2 S service Sucker Rod Pumping Workshop 17

18 Component Service Conditions Clause 6 of Part 1 discusses the need to establish the service conditions to assure the proper selection of materials that will be in the fluid flow path. The factors that need to be considered are: H2S partial pressure, in situ ph, the concentration of dissolved chloride or other halide, the presence of elemental sulfur or other oxidant, temperature, galvanic effects, mechanical stress, and time of exposure to contact with a liquid water phase Sucker Rod Pumping Workshop 18

19 Service Conditions (cont) It should be noted that exposure time especially with a liquid water phase is critical to determine appropriate cracking potential. Since the typical installation of the gas gun in the casing-tubing annulus is in produced fluids gaseous phase with no liquid water present, there should be no potential for cracking any of the gun materials. This is consistent with the long term performance of the current gas gun materials. However, it was recommended that the gas gun be made of standard certified materials for the most severe application to allow the end user the possibility of using the gun in any well location and condition Sucker Rod Pumping Workshop 19

20 Gas Gun Main Components The four main components include: The volume chamber, The various valves (1/4" and 1/2" ball valves and the check valve), The pressure gauge, and The pressure transducer diaphragm Sucker Rod Pumping Workshop 20

21 Equipment Development Process The various tables in Part 3 of the standard covering CRAs and other alloys were reviewed to determine the condition and restrictions of the normal materials to see what adjustments were required to select the pre-qualified materials to certify conformance to the standard for H 2 S service Sucker Rod Pumping Workshop 21

22 Table A.1 Guide to use selection tables 2010 Sucker Rod Pumping Workshop 22

23 Specific Standard Tables Included: Table A.7 covers the requirements for the austenitic stainless steel (UNS S0304 and S0316) used for the gun housing Table A.4 for 316 requirements for special components and surface applications for the valving Table A.16 for nickel based alloys (Monel TM ) for the pressure gauges Table A.40 for cobalt alloys used for diaphragms, pressure measuring devices and pressure seals for the pressure transducer diaphragms 2010 Sucker Rod Pumping Workshop 23

24 Conclusions It is possible to construct and certify a 5000 p.s.i. gas gun using acceptable, prequalified, standard materials for SSC/ H 2 S service. CO 2 corrosion should not be an issue at any pressure if the above materials are used since the austenitic stainless steels are resistant to this type of corrosion. Additionally, there should not be corrosion from this gas especially since there typically is no liquid water phase at the field location where the equipment is installed Sucker Rod Pumping Workshop 24

25 Recommendations Some changes may be necessary for material receiving to either have the suppliers or materials receiving mark (permanently stamp or paint/color code) these materials and components as H 2 S resistant to assure separation from other materials not specifically certified. The marked materials should be stored in separate bins from similar components and materials that are not certified for H 2 S service. An alternate solution is to order all materials for H 2 S service with the required certification documentation to be used for all gas guns, if there truly is no difference in cost from existing materials and components Sucker Rod Pumping Workshop 25

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