Execution of EPC Submarine Pipeline Projects in the Cantarell Field

Abstract

Abstract Petroleos Mexicanos (Pemex) is undertaking a major upgrade and expansion of the Cantarell oil field in the Gulf of Mexico in order to increase crude oil production and exports, curtail gas flaring, and to improve the reliability of existing facilities. Pemex Exploration and Production (PEP) awarded Bechtel a contract initially for a field development planning study and later for overall program management in late 1996. A number of engineering, procurement and construction (EPC) contracts have been let to implement these goals, including new platforms for drilling, production, nitrogen injection, gas compression, and personnel accommodations. In addition, EPC contracts have been awarded for over fifty submarine pipelines. This paper reviews the overall contracting philosophy for this massive submarine pipeline undertaking, plus it presents some interesting engineering, procurement, fabrication and construction issues that arose on three of those pipelines. Cantarell Field The Cantarell complex comprises four adjacent oil fields known as AKAL, CHAC, KUTZ, and NOHOCH. The fields are located in the Bay of Campeche, Gulf of Mexico, off the coast of the Yucatan Peninsula, approximately 80 kilometers north of Ciudad del Carmen, Campeche, México in water depths ranging from 35 meters in the south to 40 meters in the north. Pemex Exploración y Producción (PEP) is the operator. Cantarell is the most important oilfield complex in México and is the sixth largest oilfield in the world, with proven and probable hydrocarbon reserves of about 13.5 billion barrels of il equivalent. During September 1996, Cantarell produced a combined rate of approximately 1.1 million barrels of oil per day (MMBPD) horn twenty platform/complexes, which represents approximately 40 percent of México's domestic oil production. Cantarell also produced associated gas at a rate of 430 million standard cubic feet per day (MMSCFD) in September 1996. The quantity of treated lift gas transported by pipeline from onshore for oil recovery has steadily increased to the September 1996 volume of 252 MMSCFD. AKAL field is a supergiant field with almost 90 percent of current Cantarell oil production. AKAL Field was discovered in August 1977 and began initial production in June 1979. CHAC field, which has less than 4 percent of Cantarell production, was discovered in August 1976 but did not begin producing until August 1991. KUTZ field has not yet commenced production. NOHOCH field, which accounts for 5 percent of Cantarell production was discovered in March 1978 and began production in July 1979. The location of the Cantarell field is shown in Figure 1. Existing Facilities Oil is produced at 16 wellhead platforms. First-stage gas-oil separation is performed at some wellhead platforms and the crude oil is stabilized at three production complexes. Crude oil is transported via pipelines to three offshore tanker berths at Cayo Areas and to storage tanks at Dos Bocas where part of the production is exported via two offshore berths and the balance is transported inland by pipeline. Produced gas is sent onshore for treatment and consumption and the balance is returned offshore for gas lift. Crude oil from adjacent fields Ku, Maloob and Zaap (KMZ) is exported through the Cantarell facilities and currently some KMZ two phase production is processed at the Cantarell facilities. Two-phase light oil production from adjacent fields Ixtoc and Ek-Balam is stabilized in the Cantarell facilities and is sent by separate pipeline with light oil from nearby offshore fields Pol and Abkatun to Dos Bocas.