Recommended Practice on the Operation of Solution-Mined Underground Storage Facilities

API RECOMMENDED PRACTICE 1115 FIRST EDITION, SEPTEMBER 1994

REAFFIRMED, OCTOBER 2012

Recommended Practice on the Operation of Solution-Mined Underground Storage Facilities

Manufacturing, Distribution and Marketing Department

API RECOMMENDED PRACTICE 1115 FIRST EDITION, SEPTEMBER 1994

REAFFIRMED, OCTOBER 2012

SPECIAL NOTES

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Copyright © 1994 American Petroleum Institute

FOREWORD

This standard was prepared under the auspices of the API General Committee on Pipelines and provides basic guidance on the operation of solution-mined underground hydrocarbon liquid or liquefied gas storage facilities.

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 publi- cation and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict.

Suggested revisions are invited and should be submitted to the director of the Manufac- turing, Distribution and Marketing Department, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005.

CONTENTS

Page

SECTION 1—INTRODUCTION 1

1. Scope 1

2. Overview 1

3. Regulatory Requirements. 1

4. Referenced Publications. 1

5. Definitions. 1

SECTION 2—CAVERN HYDRAULICS 3

1. General 3

2. Pressure 3

   1. Casing Seat Pressure 3

   2. Maximum Allowable Operating Pressure 3

   3. Minimum Allowable Operating Pressure 3

   4. Rate of Pressure Change 4

3. Maximum Product Injection Rate 4

4. Maximum Allowable Brine Injection Rate 4

5. Pressure Surges (“Water Hammer”) 4

6. Specific Gravity 4

7. Brine Saturation 4

SECTION 3—STORED PRODUCT FACILITIES 4

1. Pumps and Compressors 4

2. Product Control 4

3. Product Measurement 4

4. Product Conditioning 5

5. Surface Product Piping 5

6. Tubular Strings 5

7. Changing the Product Stored 5

   1. General 5

   2. Potential Problems Areas and Solutions 5

SECTION 4—BRINE FACILITIES 6

1. Salinity 6

2. Brine Sources 6

3. Brine Storage Pond 6

4. Disposal. 7

5. Pumping 7

6. Measurement 7

7. Control 7

8. Product/Brine Separation Systems 7

SECTION 5—FRESH WATER FACILITIES 7

1. Source 7

2. Pumping 7

3. Measurement 8

SECTION 6—WELLHEAD/HANGING STRING 8

1. General 8

2. Planning 8

3. Safety Considerations 8

4. The Workover 8

5. Additional Tests and/or Safety Devices 8

6. Cavern Protection While Out of Service 9

SECTION 7—CAVERN INTEGRITY TESTING AND MISCELLANEOUS SURVEYS 9

1. Mechanical Integrity or Certification Testing 9

   1. General 9

   2. Brine Full Hydrostatic Pressure Test 9

   3. Nitrogen/Brine Interface Test 9

2. Frequency of Testing 9

3. Sonar Caliper Surveys. 10

4. Geophysical Logs. 10

5. Elevation Surveys 10

6. Records and Reports 10

   1. Retention 10

   2. Reporting 10

SECTION 8—ENVIRONMENTAL AND REGULATORY CONSIDERATIONS 11

SECTION 9—SECURITY 11

1. General 11

2. Area Patrol 11

3. Controlled Access 11

4. Boundary/Perimeter Control 11

5. Security Plans 11

6. Locks 11

SECTION 10—EMERGENCY PLANS 12

1. General 12

2. Suggested Contents 12

3. Mutual Aid Organizations 12

SECTION 11—SAFETY AND TRAINING 12

1. Safety Engineering Design Criteria 12

   1. General 12

   2. Cavern Safety Equipment 12

   3. Rotating Equipment 14

   4. Maintenance Access 14

2. Personnel Safety. 14

3. Contractor Safety 14

4. Operator Training 14

SECTION 12—RECORDS 15

1. General 15

2. Design and Construction Records 15

3. Regulatory Compliance Records 15

4. Maintenance Records 15

   1. Routine Maintenance 15

   2. Preventive Maintenance 15

5. Ongoing Operations Records 15

6. Operations Log Book 16

Recommended Practice on the Operation of Solution-Mined Underground Storage Facilities

SECTION 1—INTRODUCTION

1. Scope

   This recommended practice provides basic guidance on the operation of solution-mined underground hydrocarbon liquid or liquefied petroleum gas storage facilities. This document is intended for first-time cavern engineers or supervisors, but would also be valuable to those people experienced in cavern operations. This recommended prac- tice is based on the accumulated knowledge and experience of geologists, engineers, and other personnel in the petroleum industry. All aspects of solution-mined under- ground storage operation, including cavern hydraulics, brine facilities, wellhead and hanging strings, and cavern testing are covered. Users of this guide are reminded that no publi- cation of this type can be complete, nor can any written document be substituted for effective site-specific operating procedures.

   This recommended practice does not apply to caverns used for natural gas storage, waste disposal purposes, caverns which are mechanically mined, depleted petroleum reserve cavities, or other underground storage systems which are not solution-mined.

   
   

2. Overview

   Storage of products in solution-mined salt caverns has been utilized in the United States since the late 1940s. Today, storage of hydrocarbon liquids and liquefied petroleum gases in caverns developed in both domal and bedded salt forma- tions is utilized throughout the world.

   Salt caverns can act independently as long term, seasonal storage vessels; or they may serve as short term, operational storage. Caverns can also be inserted into the production plant/pipeline systems to prevent supply interruptions when maintenance or emergency shut downs occur or to “float” on pipelines to optimize operations.

   Storage of product in a salt cavern may require careful review to ensure that the product is compatible with the salt. Chemical and physical properties of the salt at the cavern depth and at the pressure anticipated should be reviewed to verify that unwanted chemical or physical reactions will not occur. Incompatibility of product and salt is rarely a problem for most hydrocarbons. Examples of exceptions are storage in bedded salt caverns where sulfides are present and storage of jet fuels with de-icing agents that absorb water.

   In summary, storage of products in salt caverns can provide an economical, safe, and environmentally sound method to store large quantities of compatible materials.

   
   

3. Regulatory Requirements

   Federal, state, and local regulations should be consulted for specific permitting and operating requirements. In most cases, regulations will have specific record keeping require- ments (i.e., casing pressure, annulus pressure, total injection rate, etc.) and will also have mechanical integrity test requirements (see Section 8).

4. Referenced Publications

   The latest editions or revisions of the following docu- ments form a part of this recommended practice to the extent specified in the text.

   API

   RP 5C1 Recommended Practice for Care and Use of Casing and Tubing

   Spec 5CT Specification for Casing and Tubing

   RP 1114 Recommended Practice for the Design of Solution-Mined Underground Storage Facil- ities

   RP 2220 Process Contractor Safety Performance

   DOT1

   49 Code of Federal Regulations, Part 192 “Transportation of Natural and Other Gas by Pipeline” and Part 195 “Transportation of Hazardous Liquids by Pipeline”

   NFPA2

   13 Standard for the Installation of Sprinkler Systems

   15 Standard for Water Spray Fixed Systems for Fire Protection

5. Definitions

   1. brine: a saltwater solution, said to be saturated when maximum salt per unit weight has been dissolved (approxi- mately 26 percent by weight at 20˚C).

   2. caprock: a mantle composed chiefly of anhydrite, gypsum, and limestone.

   3. casing shoe (casing seat): a cement base formed at the bottom of the casing which provides both an anchor and pressure containment area.

1U.S. Department of Transportation. The Code of Federal Regulations is available from the U.S. Government Printing Office, Washington, D.C. 20402.

2National Fire Protection Association, 1 Batterymarch Park, Quincy,

Massachusetts 02169-7471.

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