Poza Rica-Altamira: Mexico's Oil Roots

Poza Rica-Altamira is currently the 10th most productive asset for Pemex in terms of oil and ranks 11th in natural gas production. Averaging 67,770 b/d of oil and 119.95 mcf/d of gas in 2012, the Poza Rica-Altamira complex consists of 73 producing blocks. The most important blocks of the asset are Poza Rica and Altamira, which give the complex its name, and the blocks awarded during the second round of integrated service contracts (ISCs): Arenque, Atún, Ébano, Pánuco, San Andrés, and Tierra Blanca.

5.44 billion bbl of oil and 7.51 tcf of gas have already been extracted from the complex. However, the CNH reports that the asset holds an additional 229.1 million bbl of 1P reserves, 404.1 million bbl of 2P reserves, and 521 million bbl of 3P reserves of oil and 361.8 bcf of 1P reserves, 619.6 bcf of 2P reserves, and 751.1 bcf of 3P reserves of gas. Around 26% of the total production from this asset has come from the Poza Rica block.

Located on the coastal plains of the Gulf of Mexico, in the northern area of the State of Veracruz and the southeastcentral region of the Tampico-Misantla geological province, the Poza Rica block is expected to reach an accumulated production target of 166.2 million bbl of oil and 203.2 bcf of gas, at an expected cost of US$3.51 billion between 2011- 2025, of which US$1.73 billion would be used for capital investment and US$1.79 billion for operational costs.

The planned strategy for development and production includes acquiring 1,130 km2 of seismic information, to further drill and complete 121 wells, execute major repairs at 262 wells and continue to use water injection techniques for enhanced oil recovery. Pemex has analyzed and evaluated three alternatives for the development of the asset, which include using primary recovery techniques as well as water injection techniques, with the use of both vertical and horizontal wells and simple well-completion solutions as the first option, multiphase pumping as the second option, and twin-well-drilling as the third option.

The Altamira block, tendered in Pemex’s second round of ISCs, is also located on the coastal plains of the Gulf of Mexico, approximately 40km northwest of Tampico, in the south of Tamaulipas. Covering a surface of 1,625km2, it is located in the north part of the Tampico-Misantla Basin.

Today Altamira has relatively low quantities of hydrocarbons remaining in its geological formations. Its remaining oil reserves stand at 4.7 million bbl of 1P reserves, 8.6 million bbl of 2P reserves, and 10.9 million bbl of 3P reserves; while its remaining gas reserves stand at 0.5 bcf of 1P reserves, 0.9 bcf of 2P reserves, and 1.2 bcf of 3P reserves. This area produces heavy and extraheavy oil, with viscosity ranging from 10°API to 13°API coming mainly from the San Felipe-Agua Nueva reservoir at a 13% recovery factor. Low porosity (fluctuating around 8% phi to 12% phi) and low permeability (which varies from 1mD to 1,100 mD) allow for extraction at a depth of 150 to 500m. The conditions within the block have allowed Altamira to produce 10.89 million bbl of oil and 17.39 bcf of gas in its 87-year history.

In the period between 2006 and 2011, 32 wells were drilled and a plan to drill in 71 additional locations was presented. Pemex already has 700km of 2D seismic data, of which only 82.8km has been processed. The information obtained from data processing is extremely variable in terms of quality, because of the irregular coverage of the area. Several technical di·culties have been found with the results, making data interpretation a di·cult task. Pemex and the CNH have both agreed that reprocessing is needed for a more accurate analysis of the area.

FIRST PRODUCTION

The first successful well drilled in Poza RicaAltamira was located in the Altamira block. In 1926, Altamira-30 started producing oil from naturally fractured limy-clayey rocks at the Upper Cretaceous formations of the San FelipeAgua Nueva reservoir, which had impregnated oil thicknesses of 150 to 190m, at a depth of 379 to 376m. Maximum production from this well totaled 10,170 b/d during 1926, after which it gradually decreased to a current production of 1,100 b/d.