ABSTRACT

INTRODUCTION

The SACROC Unit, one of the nation's largest oil fields, initiated a giant carbon dioxide, (C02) injection project on January 26, 1972. This miscible flood will be the largest secondary recovery project of this type ever undertaken, and is estimated to recover an additional 230 million barrels of oil. The significance of this increase in oil reserves may be realized when it is noted that a field with reserves of this magnitude has not been discovered in the United States for 10 years-with the exception of Alaska.

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This project will require the injection of 629 billion cubic feet (37 million tons) of C02over an approximate 9 year period into 202 pattern injection wells. The total cost of the project is estimated to be in excess of $175,000,000, which includes a field C02 and water distribution system and conversion of the pattern wells to injection at SACROC, expansion of SACROC's producing and water injection facilities; the installation of the C02 delivery system and the purchase and transportation of C02 to SACROC. The C02 will be transported through a 220 mile pipeline system from Val Verde Basin gas fields in Southwest Texas to SACROC requiring 81,000 HP compressor capacity to deliver the C02 at a final pressure of 2400 psi. Canyon Reef Carriers, Inc. (CRC) has been formed by the major SACROC owners to construct and operate the C02 pipeline system.

This paper summarizes the management, engineering and planning considerations in the design and implementation of this project. It has required the assistance and cooperation of the legal, financial and engineering representatives from SACROC's major owners and a major facility expansion by the 3 gasoline plants, 5 oil pipeline companies and 2 gas purchasers' pipelines which service the SACROC Unit.

HISTORY

The SACROC Unit is located in West Texas near the town of Snyder in Scurry County, as shown in Figure 1. The 50,000 acre unit comprises 98% of the Kelly-Snyder Field and is the major unitized field among 4 units in the 35 mile by 5 mile Canyon Reef formation. The field was discovered in the fall of 1948 and by 1951 at least 2,000 wells had been drilled.

It became apparent from the rapid pressure decline that a pressure maintenance program would be required to prevent excessive loss of recoverable reserves. In 1953 the Texas Railroad Commission approved unitization of SACROC and the installation of a unique centerline water injection program. The waterflood project was initiated in 1954 and the performance since that time is shown in Figure 2. The SACROC Unit was first operated in three segments by Standard Oil Company of Texas, Sun Oil Company, and Mobil Oil Corporation under a joint Unit Manager's office until 1962 when Standard Oil of Texas (now Chevron Oil Company-Western Division) was elected operator. The Unit presently has 1256 wells which have produced more than 500 million barrels of oil to date. There are 329 working interest owners including almost all of the major oil companies in the nation and 2,750 royalty owners.

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