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 MEXICO
Central America
Mexico has a coastline that borders the Pacific Ocean,
the Gulf of California, the Gulf of Mexico and the Caribbean Sea but the
Gulf of Mexico basin and its onshore extensions are the site of all
Mexico’s oil and gas production in 5 areas; Campeche Bay, Tabasco, Vera
Cruz, Golden Lane and the Burgos Basin (gas).
Over the last decade growth in offshore oil production in
Mexico has offset declining output from old onshore fields. Most of the
offshore reservoirs are fractured carbonates in Campeche Bay containing
heavy oil, very different from US fields in the Gulf of Mexico. Such
reservoirs present problems in production and many wells are required to
sustain recovery.
 Mexico’s entire region is licensed to Pemex Exploration
and Production (PEP), the upstream subsidiary of Petroleos Mexicanos
(Pemex). Pemex has full responsibility for exploration, production and
distribution of the nation’s oil and gas and has been investing heavily
to increase output. However, due to capital constraints, there are moves
to open the oil industry to private investment and operations although
exclusive exploration and production rights or ownership of oil and gas
will not be granted to foreign companies.
To attract private capital new Multiple Services
Contracts (MSCs) were issued in 2003 covering onshore gas projects in
the Burgos Basin. Under an MSC private companies are responsible for
100% of financing and are paid for the works performed and services
rendered.
Campeche Bay: Nearly 30 oil fields are located in
a confined area of Campeche Bay (also called the Gulf of Campeche or
Campeche Sound). They are located 100 to 150 km offshore of Atasta on
the east side of the Gulf of Mexico. The fields are developed in 5
complexes, termed asset areas.
The largest, Cantarell, was discovered in 1976 and
comprises the Akal field, which holds the bulk of the reserves, and the
Chac, Kutz and Nohoch fields. In addition there are undeveloped
reserves in the deeper Sihil field below Cantarell.
Cantarell, is the highest offshore oil-producing complex
in the world, and is only second to the onshore Ghawar field in Saudi
Arabia. It lies in shallow water depths of 35m to 40m and produces from
over 30 platforms. The fields are located within a NW-SW trending
anticline and produce heavy oil, known as Maya 22, from fractured
carbonates.
The first field, Akal, came onstream in 1979 and reached
a production peak in April 1981 at 1.12 mm Bbls per day after which
pressure drops reduced output. Pemex installed a gas lift system, which
stabilised output at around 1 mm Bbls per day to 1995.
In 1996 output began increasing due to additional
drilling and installation of infrastructure (the Cantarell project) but
pressure continued to decline. To maximise output a pressure maintenance
system was designed to inject nitrogen into the gas cap, believed to be
more effective than a conventional water flood.
Nitrogen modules began operating in 2000, injecting 34 mm
cubic metres per day. Over 10 new platforms have been installed and at
least 200 wells have been drilled. The complex produced around 2.1 mm
Bbls per day in 2004 but has since declined.
With increased oil output produced gas volumes have
increased substantially. In 1996 the area could handle around 7 Bcm per
year but infrastructure has been installed to compress and handle more
gas and cease flaring. In August 2004 a new offshore gas compression
plant and processing plant was inaugurated in the Akal complex obviating
the need to send 25 million cubic metres a day of gas ashore for
processing, before being sent back as fuel for offshore operations and
for re-injection.
A smaller heavy oil area to the north of Cantarell
comprises the Ku-Maloob-Zaap assets in slightly deeper waters (100 to
200m), which will also be fully developed through the existing Cantarell
system with 4 new platforms and separation and compressor facilities.
Other complexes to the southwest of Cantarell, known as the Abkatun
assets and the Pol-Chuc assets have been producing lighter, better
quality oil for many years although output is declining.
Other Mexico: The first onshore discoveries in
Mexico were found in what became known as Golden Lane, near Tampico,
west of the Gulf of Mexico, where fractured Cretaceous carbonate
reservoirs gave exceptionally high flow rates. As a result Mexico
accounted for one quarter of global oil production during the early
years of the 20th century but the area is now in decline.
A string of small oil fields produce offshore of Golden
Lane in shallow waters around 30 km from the coast. The Lankahuasa
natural gas find and other light crude projects are due to be developed,
perhaps with MSCs.
To the east of Campeche Bay the wide shelf east, north
and west of the Yucatán peninsula has seen few wells and no discoveries.
However, Pemex intends to start drilling in 2007 on its Progreso project
in Campeche State off the west coast of the peninsula. Work in Yucatán
State territorial waters may start in 2008. The area is extremely
sensitive environmentally and, even if oil and gas were found,
production would not start for many years. Previous exploration failed
to find commercial oil and it is thought that, typically for the
northern Caribbean Sea, the area lacks source rocks.
To the west of Mexico the shelf plunges off the mountains
of the Sierra Madre into the Pacific Ocean. The southern stretch from
Guadalajara to the border with Guatemala is filled with young sediments
in a deep narrow trough but in the north, off Baja California, the
Guaymas, Viscaino and Purisimo basins have accumulated rift sediments
and gas discoveries have been made near the coast. This region has
similarities to the productive Los Angeles Basin in the US but has so
far been hardly explored.
There are also other large areas of the Gulf of Mexico
including deepwater areas, all sparsely drilled. There are high
expectations for new discoveries since the northern part of the Mexican
shelf has seen less than 10% of the wells compared to the other side of
the border. .
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