Final Draft of API RP 11V10

182 Pages·2006·4.52 MB·English

Recommended Practices for
Design and Operation of
Intermittent and Chamber
Gas-lift Wells and Systems
API RECOMMENDED PRACTICE 11V10
FIRST EDITION, JUNE 2008

Recommended Practices for
Design and Operation of
Intermittent and Chamber
Gas-lift Wells and Systems
Upstream Segment
API RECOMMENDED PRACTICE 11V10
FIRST EDITION, JUNE 2008
Special Notes
API publications necessarily address problems of a general nature. With respect to particular circumstances, local,
state, and federal laws and regulations should be reviewed.
Neither API nor any of API's employees, subcontractors, consultants, committees, or other assignees make any
warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of
the information contained herein, or assume any liability or responsibility for any use, or the results of such use, of any
information or process disclosed in this publication. Neither API nor any of API's employees, subcontractors,
consultants, or other assignees represent that use of this publication would not infringe upon privately owned rights.
Classified areas may vary depending on the location, conditions, equipment, and substances involved in any given
situation. Users of this recommended practice should consult with the appropriate authorities having jurisdiction.
Users of this recommended practice should not rely exclusively on the information contained in this document. Sound
business, scientific, engineering, and safety judgement should be used in employing the information contained
herein.
API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly train and
equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their
obligations to comply with authorities having jurisdiction.
Information concerning safety and health risks and proper precautions with respect to particular materials and
conditions should be obtained from the employer, the manufacterer or supplier of that material, or the material safety
data sheet.
API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the
accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or
guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or
damage resulting from its use or for the violation of any authorities having jurisdiction with which this publication may
conflict.
API publications are published to facilitate the broad availability of proven, sound engineering and operating
practices. These publications are not intended to obviate the need for applying sound engineering judgment
regarding when and where these publications should be utilized. The formulation and publication of API publications
is not intended in any way to inhibit anyone from using any other practices.
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is solely responsible for complying with all the applicable requirements of that standard. API does not represent,
warrant, or guarantee that such products do in fact conform to the applicable API standard.
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Copyright © 2008 American Petroleum Institute
Foreword
Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the
manufacture, sale, or use of any method, apparatus, or product covered by letters patent. Neither should anything
contained in the publication be construed as insuring anyone against liability for infringement of letters patent.
This document was produced under API standardization procedures that ensure appropriate notification and
participation in the developmental process and is designated as an API standard. Questions concerning the
interpretation of the content of this publication or comments and questions concerning the procedures under which
this publication was developed should be directed in writing to the Director of Standards, American Petroleum
Institute, 1220 L Street, N.W., Washington, D.C. 20005. Requests for permission to reproduce or translate all or any
part of the material published herein should also be addressed to the director.
Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-time
extension of up to two years may be added to this review cycle. Status of the publication can be ascertained from the
API Standards Department, telephone [phone]. A catalog of API publications and materials is published
annually and updated quarterly by API, 1220 L Street, N.W., Washington, D.C. 20005.
Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW,
Washington, D.C. 20005, [email protected].
iii

Contents
Page
1 Introduction and Organization of This Document. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Overview of Section 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Understanding Intermittent, Chamber, and Plunger Gas-lift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Deciding When Each Method is Applicable and Choosing Candidate Wells (Includes a Table for
Comparing Pros and Cons of Each Method) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Selecting the Most Appropriate Control Method(s). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.5 Designing These Types of Gas-lift Wells and Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
1.6 Troubleshooting These Types of Gas-lift Wells and Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
1.7 Operational Considerations for Individual Gas-lift Wells and Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1.8 Derivation of Important Intermittent Gas-lift Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
1.9 Detailed Example of an Intermittent Gas-lift Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2 Definition of the Intermittent Gas-lift Method and General Guidelines for its Application. . . . . . . . . . . . 36
2.1 Definition of the Intermittent Gas-lift Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2.2 General Guidelines for Intermittent Gas-lift Installations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3 Types of Intermittent Gas-lift Installations (General Description and Operation) . . . . . . . . . . . . . . . . . . . 49
3.1 Simple Completions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.2 Chamber Installations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.3 Accumulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.4 Dual Completions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.5 Gas-lift with Plungers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4 Types of Gas Injection Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.1 Choke Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.2 Surface Time Cycle Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
4.3 Controlling the Gas Injection While Unloading an Intermittent Gas-lift Well. . . . . . . . . . . . . . . . . . . . . . . 68
4.4 Variations in Time Cycle and Choke Control of Injection Gas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.5 Automatic Control with a Production Automation System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5 Design of Intermittent Gas-lift Installations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
5.1 Mandrel Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.2 Optimum Cycle Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.3 Volume of Gas Required Per Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5.4 Valve Area Ratio Calculation for Choke Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
5.5 Valve Area Ratio Calculation When Surface Time Cycle Controllers are Used. . . . . . . . . . . . . . . . . . . . . 85
5.6 Use of Mechanistic Models for Intermittent Gas-lift Design Calculations . . . . . . . . . . . . . . . . . . . . . . . . . 86
6 Troubleshooting Techniques for Intermittent Gas-lift. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.1 Information Required for Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.2 Diagnostic Tools Available for Troubleshooting Intermittent Gas-lift Installation. . . . . . . . . . . . . . . . . . . 88
6.3 Troubleshooting Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7 Operational Considerations for Intermittent Gas-lift Systems and Wells. . . . . . . . . . . . . . . . . . . . . . . . . 106
7.1 Staffing Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
7.2 Understanding the Design Philosophy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
7.3 System/Well Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
7.4 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
7.5 Analysis/Problem Detection/Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
7.6 Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
7.7 Optimization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
v
Page
Annex A Analytical Derivation of Optimum Cycle Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Annex B Intermittent Gas-lift Design—A Detailed Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Annex C Use of Field Units and SI Units Calculators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Figures
1.1 Simple Completion (Closed Installation). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 Double Packer Chamber. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
1.3 Insert Chamber. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.4 Insert Chamber with Hanger Nipple for “Stripper”-type Wells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.5 Insert Chamber with Combination Operating-bleed Valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.6 Extremely Long Insert Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
1.7 Insert Chamber for Tight Formations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
1.8 Simple Type Accumulator (Not to Scale) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
1.9 Insert Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
1.10 Parallel String Dual Completion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
1.11 Completion for Zones That are Too Far Apart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
1.12 Completion for Intermittent Gas-lift with Plungers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
2.1 Intermittent Gas-lift Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.2 Effect of Reservoir Pressure and PI on Optimum Cycle Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
2.3 Chamber Type Completions: a) with Normal Sanding Valve; b) with Extended Standing Valve . . . . . . 42
2.4 Closed Rotative Gas-lift System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.5 Separator Liquid Level vs. Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
3.1 Simple Completion (Closed Installation). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
3.2 Double Packer Chamber. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
3.3 Pressure Diagram in Dip Tube and Chamber Annulus (for High True Liquid Gradient). . . . . . . . . . . . . .53
3.4 Pressure Diagram in Dip Tube and Chamber Annulus (for High True Liquid Gradient). . . . . . . . . . . . . .53
3.5 Insert Chamber. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
3.6 Pressure-depth Diagrams for the Same Well and Three Different Types of
Completions (Beginning of Liquid Accumulation Period) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
3.7 Pressure-depth Diagrams for the Same Well and Three Different Types of
Completions (Just Before Chamber Valve Opens) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
3.8 Insert Chamber with Hanger Nipple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
3.9 Insert Chamber with Combination Operating-bleed Valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
3.10 Extremely Long Insert Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
3.11 Insert Chamber for Tight Formations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
3.12 Simple Type Accumulator (Not to Scale) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
3.13 Insert Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
3.14 Parallel String Dual Completion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
3.15 Completion for Zones That are Too Far Apart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
3.16 Completion for Intermittent Gas-lift with Plungers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64
3.17 Typical Experimental Fallback vs. Plunger Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
5.1 Graphical Procedure for Spacing Unloading Valves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78
5.2 Fallback Factor as a Function of the Total Volume of Gas Per Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
6.1 Typical Wellhead Pressure Recordings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
6.2 Cycle Frequency Effect on Minimum Wellhead Pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90
6.3 Surface Injection Pressure Recording (Choke Control) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
6.4 Typical Gas Injection Pressure Recordings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
6.5 Surface Injection Pressure Recording (Time Cycle Control) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
6.6 Examples of Inefficient Gas Injection Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
6.7 Double Packer Chamber. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100
Page
6.8 Double Packer Chamber (Initial Liquid Level Above Upper Packer). . . . . . . . . . . . . . . . . . . . . . . . . . . . .101
6.9 Downhole Pressure Survey Output (1st Stop at Wellhead, 2nd Stop at Valve Depth,
3rd Stop at Top of Perforations, 4th Stop at Valve Depth) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
6.10 Minimum Pressure Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104
A.1 Practical Range for Intermittent Lift Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119
A.2 Variables Considered by the Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .132
A.3 Downhole Pressure Survey in a Conventional Intermittent Lift Installation. . . . . . . . . . . . . . . . . . . . . . .142
A.4 Graphical Valve Spacing with Well Full of Fluid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144
Tables
C.1 Conversion Factors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .164