Abstract

The Cantarell Complex is the largest field in México and the sixth largest in the world, with original proven reserves of over 17 billion barrels of oil. It started producing in 1981 and, through 1995, produced approximately one million barrels per day.

In 1996, a redevelopment project was started to increase reserves, more than double oil production, utilize all the gas by adding sufficient compression and process capacity, and modernize the existing facilities to improve operational safety and efficiency. Overall, the design, construction, and installation of these facilities are nearly 80 percent complete.

This technical paper provides an overview of the project, a summary of the current status, and a discussion of major project achievements to date.

Introduction

The Cantarell field, located about 80 kilometers (km) offshore of the Yucatan Peninsula in the Bay of Campeche, Mexico (see Figure 1: Location of Cantarell Oil Field), is the largest oil field in Mexico.

The Cantarell field was discovered in 1976 and has a surface area of 162 square kilometers (km2). It is composed of four major fields: Akal, Nohoch, Chac, and Kutz, in addition to the reserves in the newly discovered deeper Sihil field.

These fields comprise an anticline oriented northeast to southwest. The Akal block is the largest of the complex with 91 percent of 35 billion barrels of original oil volume, followed by Nohoch, Kutz, and Chac. The average depth for the Akal field is estimated at 2,300 meters (m) below sea level.

The Cantarell crude is classified as heavy, with a density varying between 19 ° and 22 ° API and containing sulfur compounds. The producing zones consist of different geological formations that are highly fractured with abundant vugs due to dissolution, providing superlative productive capacity.

The exploitation of Cantarell began in June 1979, and reached a production peak of 1.156 million barrels of oil per day (bpd) in April 1981. By 1986, the reservoir pressure of 270 kg/cm2). had decreased by 60 percent to 172 kg/cm2. Pemex installed a lift gas system which stabilized production at approximately one million bpd until 1995.

In 1996 an increase in production began as a result of the Cantarell Project. Production reached 1.4 million bpd in 1997. By early 1999, the production in most of the wells was facilitated by lift gas, yet the bottom hole pressure had further decreased to 112 kg/cm2.

In the beginning of Cantarell field, wells were capable of producing an average of 31,000 bpd. Currently, the average production per well has been reduced to a little more than 7,000 bpd. The relationship between reservoir pressure and oil production is shown in Figure 2: Cantarell Field Production and Bottom Hole Pressure. The pressure-production history of the field indicates that each kg/cm2 of pressure reduction in the reservoir corresponds to a production loss of more than 120 bpd per well.

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