*SPE Member **Currently a PhD candidate at the U. of California

Abstract

There exists in the pipeline industry a potentially catastrophic phenomenon known as potentially catastrophic phenomenon known as ductile fracture. This report presents new technology which minimizes the effect of a ductile fracture if preventive measures fail.

Introduction

The decision to inject carbon dioxide (Co.) into oil-bearing formations for enhanced oil recovery (EOR) pioneered a new era in the oil producing industry. However, due to the super-critical (dense phase) nature of CO., CO pipelines can be vulnerable to a potentially hazardous phenomenon known as potentially hazardous phenomenon known as "ductile fracture."

In keeping with Chevron U.S.A. Inc.'s strict environmental protection policy, a recent study investigated the possibility of a ductile fracture occurring along the 220 mile (354 km] long Canyon Reef Carriers CO pipeline in West Texas. Furthermore, it is pipeline in West Texas. Furthermore, it is necessary to protect the potential loss of oil production as a result of the loss of CO involved in a ductile fracture.

A ductile fracture can be defined as a propagating crack in a length of pipe which propagating crack in a length of pipe which results from an external rupture. Corrosion, construction defects, and/or a careless backhoe operator can initiate a ductile fracture, which may travel along the pipeline for several miles, approaching the pipeline for several miles, approaching the speed of sound. The primary hazards are flying dirt, rocks, and pipe metal. Potentially harmful levels of CO, will be Potentially harmful levels of CO, will be released.

The 14 major working interest owners of the SACROC Unit formed Canyon Reef Carriers, Inc. (CRC) for the purpose of constructing a $46 million pipeline to meet the SAC Unit's CO2 flooding needs. EOR production commenced with the flow of CO, to the SACROC Unit in February 1972.

The Canyon Reef Carriers Pipeline (CRC Pipeline) currently has a maximum capacity Pipeline) currently has a maximum capacity of 200 million ft' per day [6 Mm' per day) and utilizes 90,650 hp (67,571 kw] of compression. The pipeline begins adjacent to Shell Oil Company's Terrell Plant in northeastern Terrell County, Texas and traverses ten West Texas counties in a generally northeastern direction to the SACROC Unit in Scurry County, Texas (see Figure 1). Figure 2 shows the CRC Pipeline's location with respect to other Pipeline's location with respect to other CO. pipelines servicing other CO sources and/or CO, floods. The CRC Pipeline is 220 miles [354 kml long, consisting of 40 miles [64 km] of 12.75 in. (32.38 cm] outside diameter (O.D.), 0.344 in. [0.874 cm] wall, API X-65 and 180 miles [290 km] of 16 in. (41 cm] O.D., 0.375 in. [0.952 cm) wall, API X-60 pipe. There are 24 mainline valves (MLV, ls) spaced an average of 11 miles [18 km] apart in 20 MLV sections. The maximum absolute operating pressure is 2,025 psig (14 MPa]. Pipeline operating pressure averages 1,500 psig [10 MPa].

The CRC Pipeline system gathers tailgate CO, from four adjacent gas processing plants (Terrell, Grey Ranch, Mitchell, and Puckett) as shown in Figures 1 and 2. Each plant services a Val Verde Basin natural gas field where raw gas consisting of methane with 25 to 50 percent by volume of CO, as well as minor quantities of heavy hydrocarbons, nitrogen (N,) and hydrogen sulfide (H,S) is produced. produced. P. 311

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