High Pressure and Sub-Sea Gas-Lift
Document Outline
API RECOMMENDED PRACTICE 19G13 (RP 19G13)
DRAFT #4, February 5, 2010
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API RP 19G13 High Pressure and Sub-Sea Gas-Lift Page 1
Foreword
This Recommended Practice (RP) is under the jurisdiction of the API Committee on Standardization of Production Equipment (Committee 19).
This document presents Recommended Practices for high Pressure and Sub-Sea Gas-Lift. Other API Specifications, API Recommended Practices, and Gas Processors Suppliers Association (GPSA) documents may be referenced and should be used for assistance in design and operation.
API Recommended Practices may be used by anyone desiring to do so, and diligent effort has been made by the Institute to assure the accuracy and reliability of the data contained therein. However, the Institute makes no representation, warranty, or guarantee in connection with the publication of any API Recommended Practice and hereby expressly disclaims any liability or responsibility for loss or damage resulting from their use, for any violation of any federal, state, or municipal regulation with which an API Standard may conflict, or for the infringement of any patent resulting from the use of an API Recommended Practice or Specification.
Note:
This is the first edition of this recommended practice.
Requests for permission to reproduce or translate all or any part of the material published herein should be addressed to the Director, American Petroleum Institute, 1220 L Street NW, Washington DC 20005-4070
This Recommended Practice shall become effective on the date printed on the cover but may be used voluntarily from the date of distribution.
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Recommended Practices for
High Pressure and Sub-Sea Gas-Lift
API RP 19G13
Generic Document Outline
as Provided by API
Note: The next three pages contain a generic outline provided by API that all API Recommended Practices are to use. The “n” pages following the generic outline contain the table of contents (TOC) for Section VII (Requirements or Recommended Practices) contained in this document. The pages following the TOC contain the draft of the actual document. The TOC is for use during preparation of the document only. It will be removed when the document is finished and ready for submission to the API for publication.
I. Forward
The foreword consists of a specific part and a general part.
The specific part (supplied by the committee) should contain any specific information a committee wants to convey to the public such as a statement of significant technical changes from any previous edition of the document or the relationship of the document to other documents.
The general part (supplied by API staff) gives information relating to the document such as the committee responsible for preparing the document, the effective date, terms of use, and contact information to submit suggested revisions.
II. Introduction
The introduction is an optional preliminary element used, if required, to give specific information or commentary about the technical content of the document, and about the reasons prompting its preparation. It shall not contain requirements.
The introduction shall not be numbered unless there is a need to create numbered subdivisions. In this case, it shall be numbered 0, with subsections being numbered 0.1, 0.2, etc. Any numbered figure, table, displayed equation or footnote shall be numbered normally beginning with 1.
III. Scope
This element shall appear at the beginning of each document and define without ambiguity the subject of the document and the aspects covered, thereby indicating the limits of applicability of the document or particular parts of it. It shall not contain requirements.
In documents that are subdivided into parts, the scope of each part shall define the subject of that part only.
The scope shall be succinct so that it can be used as a summary for bibliographic purposes and the API Publications Catalog (www.api.org/publications).
IV. Normative References
This optional element shall give a list of the referenced documents cited in the document in such a way as to make them indispensable for the application of the document. References may be general or specific. It is recommended that general references be used unless there are technical reasons why a specific edition must be referenced. When a general reference is to all parts of a document, the publication number shall be followed by the indication “(all parts)” and the general title of the series of parts. For specific references, each shall be given with its edition number (or year of publication). The year of publication or dash shall not be given for undated references.
The list shall be introduced by the following wording:
“The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document applies (including any addenda/errata).”
V. Terms and Definitions
This is an optional element giving definitions necessary for the understanding of certain terms used in the document. The following introductory wording shall be used where all terms and definitions are given in the document itself:
“For the purposes of this document, the following terms and definitions apply.”
In the case where terms defined in one or more other documents also apply (e.g. in the case of a series of associated documents where Part 1 specifies the terms and definitions for several or all of the parts), the following introductory wording shall be used, altered as necessary:
“For the purposes of this document, the terms and definitions given in...and the following apply.”
Rules for the presentation of terms and definitions are provided in Annex E.
VI. Symbols and Abbreviations
This is an optional element giving a list of the symbols and abbreviations necessary for the understanding of the document. Unless there is a need to list symbols in a specific order to reflect technical criteria, all symbols should be listed in alphabetical order in the following sequence:
— Upper case Latin letter followed by lowercase Latin letter (A, a, B, b, etc.);
— Letters without indices preceding letters with indices, and with letter indices preceding numerical ones (B, b, C, Cm , C2 , c, d, dext , dint , d1, etc.);
— Greek letters following Latin letters (A, B,...Z, α, β,...z, etc.);
— Any other special symbols.
Per API style guidelines, variables are set in Times New Roman/Italic in the equations and when referenced in the text; however, symbols, numbers, abbreviations and acronyms are not italicized.
For convenience, this element may be combined with the Terms and Definitions element in order to bring together terms and their definitions, abbreviated terms, symbols, and perhaps units under an appropriate composite title, e.g. “Terms, Definitions, Abbreviations, Symbols, and Units.”
See E.5 for additional information on symbols and abbreviated terms.
VII. Requirements
Here is the meat of the document
VIII. Annexes
Annexes should appear in the order in which they are referenced in the body of the standard (e.g. the first annex mentioned should be Annex A, the second Annex B, and so on). Note that this rule means that normative and informative annexes will be intermixed. An exception to this rule is the bibliography (see 6.6.9). The bibliography shall be the last annex of the standard (in instances where an index exists, all annexes would precede the index). See 5.3.6 for more information on annexes.
IX. Bibliography
A bibliography, if present, shall appear after the last annex. The bibliography should include the following:
a) Referenced documents that are cited in an informative manner,
b) Referenced documents that are bibliographic or background material in the preparation and application of the document.
If bibliographic items are cited in text, figures, or notes, the citation shall be placed in brackets at the point where reference is made and shall be numbered consecutively e.g. [1]. Lists of bibliographic references are normally arranged either alphabetically by the first element or in numeric sequence corresponding to the order of citation in the text.
Documents already listed in the normative references section shall not be included in the bibliography.
Recommended Practices for
High Pressure and Sub-Sea Gas-Lift
API RP 19G13
Table of Contents
Forward
To be drafted by Wayne Mabry and Cleon Dunham.
Introduction
To be drafted by Wayne Mabry and Cleon Dunham.
1. Scope
To be drafted by Wayne Mabry and Cleon Dunham.
2. Normative References
To be prepared by the Work Group as the project unfolds.
3. Terms and Definitions
To be prepared by the Work Group as the project unfolds.
4. Symbols and Abbreviations
To be prepared by the Work Group as the project unfolds.
5. Requirements
At this time, we envision four major sections in the document to cover Land-Based Gas-Lift, Dry Three (Platform Based) Gas-Lift, Sub-Sea Gas-Lift, and Normal Pressure Sub-Sea Gas-Lift. The first step will be to prepare outlines for each of the four sections, and then to harmonize these outlines so there is consistency on form and format. The people assigned to produce the initial outlines are:
· Land based gas-lift: Tom Nations, with help by Bryan Freeman, Mike Johnson, Ian Schuur, and Stan Groff.
· Dry tree based gas-lift: Keith Fangmeier, with help by Jim Hall and Nora Ghobrial.
· Sub-sea gas-lift: Tom Norland, with help by Wayne Mabry and Wim DerKinderen.
· Normal pressure sub-sea gas-lift: Mike Johnson
· Harmonization of the Outlines and Text. Wayne Mabry and Cleon Dunham.
Each section will address the following topics. Some of the sub-sections may not be pertinent in each section. If some sub-sections are repetitive, they can be included as annexes and cross-referenced with the rest of the document.
For purposes of this document:
· High pressure will be defined as 2,000 psi (xxx kPa) and above. This is based on a 900 ANSI, B16.5 flange rating, with some reduction to a logical limit.
· High pressure will be in a range of from 2,000 to 5,000 psi.
· The ultra high pressure range will be above 5,000 psi.
Note: This section contains draft outlines for the four sections of this recommended practice. When an outline is completed, it will be moved to the Master Document where the sections can be written. Theses are shown in blue.
When a section has been drafted, the color of the outline will be changed to yellow.
5.1 High Pressure Land-Based Gas-Lift
Author(s) / Target Date / StatusLead - Tom Nations
Bryan Freeman
Mike Johnson
Ian Schuur
Stan Groff
Outline version 1
The scope of this document is intended to address the special requirements and recommended practices associated with applying gas-lift in wells where high pressures are required, both onshore and offshore.
High Pressure gas lift gas availability, measurement, and quality (high pressure gas definition is minimum 2,000 psi)
The scope of the documents will address the followign topics, plus others.
(1) Types of equipment (design considerations for burst/collapse/pressure rating for life of well)
(a) Surface Equipment
(i) Gas lift distribution manifold and surface lines
1. HSE considerations: In comparison with normal gas lift, high pressure gas lift operations generate additional set of HSE risks. This recommended practice may serve as a guide to identifying these risks and providing some mitigation suggestion. It is up to the user to ensure all risks are identified and mitigated as necessary.
2. Regulatory agencies and field regulations: This recommended practice does not superseed or replace any statutory or regulatory requirements.
3. Maintenance/inspection program for pressure relief valves: Pressure relief valves should be on a regular maintenance program to ensure the pressure limitations of the surface equipment are not exceeded at any time.
4. Pressure rating/integrity, new design/retrofitting: Pressure rating of equipment should be as per manufacturer stated working pressure, the system working pressure should only be as high as the lowest rating in the system. The working pressure rating capability of the system should be validated on a regular basis.
5. Erosion/corrosion: Surface equipment should be monitoted for erosion and corosion so as to ensure its integrity and pressure retention capabilities.
6. Gas scrubbing/cleaning
a. NGL’s impact at higher pressures
(ii) Wellhead
1. Pressure rating/integrity: High pressure gas lift applications require higher annulus pressures than those of normal gas lift applications, though they may have similar tubing pressures at the well head. Both the annulus and tubing pressures need to be considered when evaluating the suitability of a new or existing well head configuration.
2. Elastomers – explosive decompression issues when converting to high pressure gas lift.: Higher gas pressures, if not properly managed, may damage elastomers by explosive decompression. When selecting surface equipment, the possibilty of a significant gas pressure drop should be considered as this may damage elastomer seals.
3. Flanged and welded connections – not threaded: Though threaded high pressure connections are available, most surface connnections are of line pipe style and, due to their thin cross-sections at the connections, are not recommended for higher pressure gas lift injection lines. Flanged connections provide a higher safety factor and are less impacted by erosion/corosion.
(iii) Separators
1. Flowlines between wellhead and separator: The flowlines should be suitable to retain the operating pressures and any fluctuations that they may be exposed to.
2. Over/under pressure prevention system: Care should be taken to accurately select the operating pressure of both the downstream pressure retaining equipment and consideration should be given to ensure safe operating limits are not exceeded.
3. Maintenance/inspection program for pressure relief valves/pilots: It is recommneded that the downstream safety euqipment be placed on a regular maintenance schedule applicable to the equipment.
(iv) Collapse considerations when casing annulus pressure is bled down: Explosive decompression of elastomers should be considered whenever a high pressure gas bleed down event is planned or expected. Rapid drop of gas inpregnated elastomers may impact seal integrity and require in intervention to remedy.
(v) Other?
(b) Downhole equipment
(i) Tubing and casing design
1. Burst/collapse considerations: High pressure gas lift applications typically expose the production tubing to increased differential pressures. In most cases this differential pressure acts as a burst load, with the annulus acting as the injection gas conduit.
(ii) Gas-lift equipment
1. Refer to relevant API, ISO, and other industry standard documents
a. API 11V1 (gas lift product specification)
b. ISO 17078-1 and -2 (gas lift equipment, mandrels and valves respectively)
c. WR0534 (Statoil barrier seal qualification standard)
d. ISO 14310 V1 Leak rate specification for Packer and Bridge Plug Product (is there one for gas lift eqpt?)
(iii) Other downhole equipment
1. SSSV
a. Elastomers
b. Annular restriction
c. Production Flow restriction
d. API 14A (ISO 10432) safety valve specifications
2. Nipples
a. Flow restriction
b. Completion equipment
(2) Location of gas-lift injection
(a) Single injection point
(b) Use IPO valves for unloading stations if required
(i) High dome charge pressures
(ii) Special handling procedures for transportation to well location
(3) Operational Issues
(a) Flow assurance
(i) Hydrates
(ii) Jules-Thompson (freezing)
(iii) Dehydration (erosional effects)
(iv) Solids deposition
(v) Erosion
(vi) Corrosion
(b) Unloading, start up
(i) Downhole differential pressure, collapse/burst
(ii) Rates and velocities through valves and orifices (erosion)
(c) Shut down and restart
(d) Optimizaton & Troubleshooting
(i) Downhole monitoring
(ii) Multi-phase flow modeling
(iii) Well production rate testing, tied to gas-lift optimization
(4) Intervention techniques
(a) Pressure control on lubricators and other servicing equipment
(b)
(5) Dynamics, e.g. pressure fluctuations in long flowlines and risers
(i)
(ii)
(6) Fluid issues
(a) Impact of fluid properties, gas absorption/re-absorption
(b) Formation of asphaltines/parafins
(c) Formation of hydrates
(d) Very high or low temperature issues
5.2 Deep Water Dry Tree (Platform Based) Gas-Lift