Mexican Maya is the flagship heavy sour export grade of Pemex, the Mexican state oil company. For four decades it has been one of the most important heavy crude grades in global trade, with U.S. Gulf Coast refiners building substantial coking and hydrotreating complexity specifically to process Maya volumes that historically reached 1.5 million barrels per day or more. The relationship between Mexican Maya production and U.S. Gulf refining is one of the most consequential structural features of the North American oil market — and the protracted decline of Mexican production over the past two decades has been one of the most important slow-motion changes in global heavy crude availability.
Understanding Maya requires understanding both the field-level production story (dominated for decades by the giant Cantarell complex and now by the Ku-Maloob-Zaap complex) and the Pemex institutional context that has constrained the country's ability to arrest the production decline.
Maya is quoted as a differential to a basket of references including WTI and US Gulf sour grades. The chart above shows the WTI reference; current Maya pricing differentials are published by Pemex through monthly formula prices.
Quality Specifications
Maya is a heavy sour blend with API gravity of approximately 22°, comparable to Venezuelan Merey and slightly heavier than Western Canadian Select's 20.5-22° API range. Sulfur content is approximately 3.3% by weight — sour by any meaningful definition, well above the 0.5% sweet/sour threshold and substantially higher than Middle Eastern sour grades like Dubai (2.0%).
The heavy-sour profile means a Maya barrel yields a relatively low share of high-value light products (gasoline, jet fuel) and a high share of middle distillates, heavy fuel oil, and residual fractions. Converting Maya into the modern slate of low-sulfur transport fuels requires substantial coking and hydrotreating capacity — exactly the complexity that distinguishes the most sophisticated U.S. Gulf Coast refineries.
Production gathered into the Maya stream comes from a number of offshore Bay of Campeche fields plus some onshore Mexican production blended to meet the named grade specification. The blend has been quality-consistent over decades, supporting the long-term commercial relationships built around it.
The Cantarell Story
The Cantarell complex, located offshore in the Bay of Campeche, was for decades the single most important producing asset for Mexico and one of the largest oil fields in the world. Discovered in 1976 (with discovery attributed to a fisherman named Rudesindo Cantarell whose nets caught the surface oil seep), Cantarell was brought into production in 1979 and grew through subsequent decades into a production juggernaut.
Cantarell's peak production exceeded 2.1 million barrels per day in 2004, making it briefly the second most productive oil field in the world after Saudi Ghawar. The decline that followed was steep and rapid — by 2010, Cantarell production had fallen below 600,000 barrels per day; by the mid-2020s, production was a small fraction of peak. The decline was driven by reservoir depletion that exceeded the rate at which enhanced recovery techniques (including the massive nitrogen injection program that had supported peak production) could compensate.
Cantarell's collapse is one of the most-studied examples of accelerated decline in a giant offshore field. The reservoir physics — particularly the speed at which the gas-oil contact moved through the reservoir under nitrogen pressure maintenance — produced a steeper decline profile than typical onshore giants. The Cantarell decline is the single largest negative contributor to the Mexican production trajectory over the past two decades.
The Ku-Maloob-Zaap Era
As Cantarell declined, the Ku-Maloob-Zaap (KMZ) complex emerged as the new dominant Mexican producing asset. Located adjacent to Cantarell in the Bay of Campeche, KMZ consists of three connected fields (Ku, Maloob, and Zaap) developed as an integrated complex. KMZ production peaked at approximately 850,000 barrels per day in the mid-2010s and has subsequently declined as the complex matures.
KMZ produces the heaviest crude in the Mexican system — even heavier than the traditional Maya blend — and the field's production characteristics have driven Maya's overall quality slightly heavier over time. The complex remains the single largest producing asset in Mexico despite its own decline trajectory.
Beyond KMZ and the legacy Cantarell production, the Mexican upstream includes a long tail of smaller offshore and onshore fields, plus the controversial new Dos Bocas refinery's anchor field Quesqui and the recent shallow-water and onshore developments that have constituted the bulk of Pemex's new project investment over the past decade.
The Pemex Pricing Model
Pemex sets monthly formula prices for Maya rather than retroactive Official Selling Prices. The formulas express Maya as a differential to a basket of reference grades — typically including U.S. heavy sour benchmarks (LLS, WTS), the broader sour crude assessments, and high-sulfur fuel oil components — rather than to a single benchmark like Brent or WTI.
The formula approach allows Maya pricing to reflect refining economics in different regions. The Asian-bound Maya formula and the U.S. Gulf-bound Maya formula differ in their underlying reference weights, reflecting the different competitive crude pools in each region. For U.S. Gulf refiners, Maya competes with Venezuelan Merey, Canadian heavy crude (WCS), Saudi Arab Heavy, and other heavy sour grades; for Asian buyers, Maya competes with Middle Eastern sour grades and other heavy supply.
The pricing methodology has been refined multiple times over Maya's history. The 2004 introduction of a coker-margin-based pricing formula was a particularly notable innovation that more accurately captured the value Maya provided to complex refiners.
The U.S. Gulf Coast Refining Relationship
The single most important structural feature of Maya is its role as the original anchor feedstock for U.S. Gulf Coast complex refining. Refineries built or upgraded during the 1980s and 1990s — Motiva Port Arthur, Valero's Texas City and Corpus Christi facilities, Marathon's Galveston Bay, Phillips 66's Sweeny, ExxonMobil's Baytown, and others — invested billions in coking units and hydrotreating capacity specifically to process Maya and similar heavy sour grades into the gasoline, diesel, and jet fuel the U.S. market demanded.
The relationship is symbiotic but increasingly asymmetric. U.S. Gulf Coast complex refineries depend on a heavy sour feedstock supply that has shrunk as Mexican production has declined. The gap has been partially filled by Canadian heavy crude (especially since the Trans Mountain Expansion pipeline opened additional supply routes), Venezuelan crude (under the Chevron license), and various Latin American heavies, but the integrated refining economics that originally made sense around stable Maya supply have become more complicated.
Maya volumes reaching U.S. refiners have declined from peak levels above 1.5 million barrels per day to typically below 500,000 barrels per day in recent years. The decline reflects both Pemex's reduced overall export availability (as Mexican domestic refining intake has grown) and Mexican strategic decisions to direct more crude toward Asian markets.
The Dos Bocas Effect
The 2022-2024 commissioning of Pemex's Dos Bocas refinery (officially the Olmeca Refinery) has reshaped Mexican crude allocation. The 340,000-barrel-per-day facility, built as a flagship project of the AMLO administration, processes heavy Mexican crude and reduces the volume available for export. The project has been controversial — both for cost overruns relative to original budgets and for the broader strategic logic of expanding domestic refining when Mexican upstream production has been declining — but it has had real impact on Mexican crude allocation.
Combined with the existing six Pemex refineries, Mexican domestic refining intake now competes meaningfully with export availability for the limited Mexican crude pool. U.S. Gulf Coast refiners that depended on Maya supply have had to adjust crude slates accordingly.
What Drives Maya Pricing
U.S. Gulf Coast heavy sour refining margins. Strong margins for coking-heavy refineries tighten Maya differentials.
Canadian heavy crude availability. WCS volumes via the Keystone system and TMX compete directly with Maya in U.S. Gulf markets.
Venezuelan crude flows. Chevron-license Merey volumes compete with Maya in the same refining slots.
Pemex export allocation. Mexican strategic decisions about Asian vs U.S. Gulf flow direction.
Mexican domestic refining throughput. Dos Bocas and other Pemex refinery operations reduce export availability.
Production decline. Long-term Mexican upstream production trajectory determines the absolute volume available.
SPR sour crude operations. U.S. Strategic Petroleum Reserve sour barrel activities affect Gulf Coast sour market balance.
Maya in One Sentence
Mexican Maya is the heavy sour crude grade that built the modern U.S. Gulf Coast refining complex — Pemex's flagship export blend whose quality drove decades of complex refinery investment and whose protracted production decline has reshaped North American heavy crude trade.
Continue Reading
- Mexico oil — the country-level Pemex story
- What is Western Canadian Select — competing heavy sour supply
- What is Mars crude — U.S. Gulf medium sour benchmark
- Venezuela oil — the other major heavy crude producer
- Oil market glossary