Prospective Resources as of January 1, 2009

Transcription

1 Hydrocarbon Reserves of Mexico Prospective Resources as of January 1, Mexico s prospective resources and their distribution in the most important producing basins are listed in this chapter. Petróleos Mexicanos has continued and intensified its exploratory activities on the coastal plain, the continental shelf and in the deep waters of the Gulf of Mexico, where the acquisition and interpretation of geological and geophysical information have made it possible to estimate the magnitude of Mexico s oil potential. Consequently, this potential resource, also known as a prospective resource, amounted to a volume of 52,300 million barrels of oil equivalent as of January 1, The distribution of prospective resources is described in Figure 3.1, where the Southeastern and Gulf of Mexico Deepwater basins stand out with 88.3 percent of the country s total prospective resources. The prospective resources are used to define the exploratory strategy and thus program the physical and investment activities aimed at discovering new hydrocarbon reserves, which would make it possible to replace the reserves of the currently producing fields and to provide medium- and long-term sustainability for the organization. In this context, the exploratory strategy is focused on the Southeastern and Gulf of Mexico Deepwater basins, mostly in the search for oil, while in the Sabinas, Producer Basins Crude Oil and Associated Gas Non-associated Gas W N S E Prospective Resource Bboe 1. Sabinas Burgos Tampico-Misantla Veracruz Southeastern Gulf of Mexico Deepwater Yucatan Shelf 0.3 Total Km 5 7 Figure 3.1 Distribution of Mexico s prospective resources. 11

2 Prospective Resources Burgos and Veracruz basins, the effort is still centered on discovering new fields of non-associated gas. 3.1 Mexico s Most Important Production Basins Sabinas Basin Oil exploration in the basin was initiated by foreign companies in 1921 and later continued as a nationalized industry after The first discovery was made in 1974 in the Monclova-Buena Suerte field with nonassociated gas production in Lower Cretaceous rock; to date, four plays have been established, two in the Upper Jurassic (La Gloria and La Casita) and two in the Lower Cretaceous (Padilla and La Virgen), which have produced 434 billion cubic feet of gas extracted from 23 fields discovered, 18 of which are active with a remaining total reserve of 53 million barrels of oil equivalent. Geologically, the Sabinas Mesozoic Basin corresponds to an intracratonic basin formed by three paleoelements; the Tamaulipas paleopeninsula, the Coahuila paleoisland and the Sabinas Basin. Five fracturing patterns have been identified in the Sabinas Basin associated with compressive forces, of which only two are considered important for the generation of naturally fractured hydrocarbon reservoirs and they are: a) Fractures as a result of the compression, parallel to the direction of the dipping layer extending along great distances, laterally as wells as vertically, b) Fractures due to extension, perpendicular to the fold axis, Figure 3.2. The total prospective resource of the Sabinas Basin has been estimated at 300 million barrels of oil equivalent, of which 279 million barrels of oil equivalent have been documented, which means 93 percent. Thus, N 102º 101º 100º W S E A Salt Dome Anticline USA 28º Inverse Fault B A C A D 27º B Monclova C B D A B C D Salt Detachment Basement Inverse Faulting Smooth Folding Domes and Salt Detachments 26º Monterrey Saltillo Figure 3.2 Structural styles of the Sabinas Basin km 12

3 Hydrocarbon Reserves of Mexico Table 3.1 Prospective resources documented in the Sabinas Basin by hydrocarbon type. Hydrocarbon Type Exploratory Wells Prospective Resources number MMboe Dry Gas Total exploratory opportunities have been recorded; the remaining 7 percent is still being documented, Table 3.1. forms part of the Río Bravo basin that regionally covers the southeastern tip of Texas and the northern part of the states of Tamaulipas and Nuevo León. Burgos Basin The Mesozoic geological structure of the Burgos Basin corresponds to a shallow marine basin with broad platforms, where there were deposits of sandstone, evaporites, limestone and shale starting from the Upper Jurassic to the end of the Mesozoic. This sedimentary carpet was lifted and folded to the west of the basin in the Late Cretaceous as a result of the Laramide Orogeny event that gave rise to the huge structural folds of the Sierra Madre Oriental. This basin was first explored in 1942 and production commenced in 1945 with the discovery and development of the Misión field, near the city of Reynosa, Tamaulipas. Since then, 227 fields have been discovered, of which 194 are currently active. Reactivation of the basin commenced in 1994 with the application of new work concepts and technologies that made it possible to increase the average daily production from 220 million cubic feet of natural gas in 1994 to 1,383 billion cubic feet per day on average in 2008, which means a cumulative production of 10,020 billion cubic feet. The remaining total reserves amount to 910 million barrels of oil equivalent. The Burgos Basin is defined by a powerful sedimentary package of Mesozoic and Tertiary rocks accumulated on the western margin of Gulf of Mexico. Geologically it Múzquiz Presa Falcón Herreras This rise was accompanied by the development of basins parallel to the folded belt, including the Burgos Basin to the front of the Sierra Madre Oriental, where the paleoelements of the Tamaulipas peninsula and Isla de San Carlos were the western limit of the depocenter, which operated as a reception center for a large volume of tertiary sediments and where the limit is established regarding the structural styles that acted in the conformation of the Burgos Basin structural framework, with normal listric growth faulting and Camargo Yegua Reynosa Miocene Queen City O. Vicksburg O. Frío O. Anáhuac P. Midway Figure 3.3 Schematic structural section of the Burgos Basin. 13

4 Prospective Resources Table 3.2 Prospective resources documented in the Burgos Basin by hydrocarbon type. Hydrocarbon Type Exploratory Wells Prospective Resources number MMboe Light Oil Dry Gas Wet Gas 364 1,478 Total 504 2,000 later reactivations of the terminal part of the Laramide Orogeny at the end of the Oligocene. The sequences of sandstone and shale environments that vary from marginal to marine, prograded over the edge of the Cretaceous platform and a Cenozoic sedimentary column was deposited, that is approximately 10,000 meters thick, Figure 3.3. The Burgos Basin has a total prospective resource of 3,100 million barrels of oil equivalent, of which 2,000 million barrels have been documented, which means 65 percent of the potential recorded in 504 exploratory opportunities; the remaining 35 percent is still being documented, Table 3.2. and Arenque fields (the latter is offshore). Production was established in the southern part of the basin in 1908 in the area which is now known as the Faja de Oro, which, after the discovery of its southern and offshore extensions has produced more than 1,500 million barrels of oil equivalent from calcareous reef Tamaulipas Arch Tamaulipas- Constituciones Ebano Pánuco Tampico Arenque 200 m W Gulf of Mexico N S E Tampico-Misantla Basin The Tampico-Misantla Basin, with an area of 50,000 square kilometers, including the offshore portion, is Mexico s oldest oilproducing basin. Activity began in 1904 with the discovery of the Ébano-Pánuco province, which has produced more than 1,000 million barrels of heavy oil from the calcareous rocks of the Late Cretaceous. The basin also produces from the oolitic limestones of the Upper Kimmeridgian and chalk of the Lower Cretaceous in the Tamaulipas-Constituciones, San Andrés 0 Chicontepec Sierra Madre Oriental 100 km Faja de Oro Atoll Poza Rica SanAndrés Figure 3.4 Map of the Tampico-Misantla Basin showing the most important areas. 14

5 Hydrocarbon Reserves of Mexico Table 3.3 Prospective resources documented in the Tampico-Misantla Basin by hydrocarbon type. Hydrocarbon Type Exploratory Wells Prospective Resources number MMboe Heavy Oil 4 44 Light Oil Dry Gas Total 118 1,123 rocks of the Middle Cretaceous that surround the atoll developed on the Tuxpan Platform. Bordering the Faja de Oro fields, there is a second strip that produces from rocks in the platform deposited as debris flows on the reef slopes. The famous stratigraphic trap known as the Poza Rica field, with a cumulative production of 1,731 million barrels of oil equivalent is the most important accumulation within this play. In this basin, the Paleocanal de Chicontepec covering an area of 3,000 square kilometers was developed to the west of the Faja de Oro, Figure 3.4. The paleocanal is mostly made up of siliciclastic sediments of the Paleocene and Eocene. The Córdoba Mesozoic Platform consisting of Mesozoic calcareous rocks whose stratigraphy is the result of processes related to relative sea water level cycles and/or tectonic pulses. These processes started to form limestone platforms (Córdoba Platform) and associated basins (Veracruz Tertiary Basin) in the Lower Cretaceous that constituted the fundamental stratigraphic domains which began during the Mesozoic. The buried structural front of the folded and faulted belt that forms the Sierra Madre Oriental, also known as the Córdoba Platform, is made up of limestones of the Middle-Upper Cretaceous that produce middle to heavy oil and sour wet gas. The Tampico-Misantla Basin reported an average production of 85,038 barrels of oil per day in December 2008, after having reached a maximum of 600,000 barrels per day in The remaining total reserves are 18,497 million barrels of oil equivalent. The Tampico-Misantla Basin has a total prospective resource of 1,700 million barrels of oil equivalent, of which 1,123 million barrels of oil equivalent have been documented, this represents 66 percent of the total recorded in 118 exploratory opportunities; the remaining 34 percent is in the process of being documented, Table 3.3. Veracruz Basin The Veracruz Basin, Figure 3.5, is made up of two well-defined geological units: The Veracruz Tertiary Basin that is made up of by Tertiary siliciclastic rocks was formed during the Paleocene-Oligocene. The sedimentation comes from igneous events (Alto de Santa Ana), metamorphic (La Mixtequita, Sierra Juárez and Macizo de Chiapas), and carbonated (Córdoba Platform) and correspond to an alternating sequence of widely-distributed shale, sandstone and conglomerates (debris, fan and channel flows). The sedimentary column includes the established and hypothetical plays of the Paleogene and the Neogene, ranging from a few dozen meters on the western edge to more than 9,000 meters in the depocenter. The Veracruz Tertiary Basin produces dry gas in the Cocuite, Lizamba, Vistoso, Apertura, Madera, Arquimia and Papán fields, and oil to a lesser extent in the fields on the western edge such as Perdíz-Mocarroca. Additionally, there is 15

6 Prospective Resources N 673 Km² W E S Veracruz 181 Km² Folded Thrust Belt Cocuite 3D Seismic 286 Km² 0 25 km Tezonapa 2 1 Mata Pionche Field Cocuite Field Miocene-Pliocene 5 10 Lower Miocene Paleocene-Eocene-Oligocene Km Figure 3.5 Subprovinces of the Veracruz Basin. considerable hydrocarbon accumulation potential in the areas geologically analogous to the areas currently producing. As a result of Pemex s strategy focused on the search for non-associated gas, the basin was reactivated through an intense campaign of seismic acquisition and exploratory drilling, which led to discoveries that now make it Mexico s second most important producer of non-associated gas; with an average production of 957 million cubic feet per day in The remaining total reserves of the Veracruz Basin amount to 265 million barrels of crude oil equivalent. The Veracruz Basin has a total prospective resource of 700 million barrels of oil equivalent, of which 571 million barrels have been documented, that is, 82 Table 3.4 Prospective resources documented in the Veracruz Basin by hydrocarbon type. Hydrocarbon Type Exploratory Wells Prospective Resources number MMboe Heavy Oil 6 52 Light Oil 9 54 Dry Gas Wet Gas Total

7 Hydrocarbon Reserves of Mexico percent of the potential recorded in 237 exploratory opportunities; the remaining 18 percent is still being documented, Table 3.4. The Salina del Istmo province, with an area of around 15,300 square kilometers is a pile of siliciclastic sediments intruded by salt that produces light oils, mostly from the plays that underlay, overlay or terminate against the allochthonous salt of Jurassic origin. Southeastern Basins The basins cover an area of 65,100 square kilometers, including the offshore portion, Figure 3.6. Exploratory jobs date back to 1905 when the Capoacán-1 and San Cristóbal-1 wells were drilled. These basins have been Mexico s most important oil producers since the 1970s. They are made up of five provinces: The Chiapas-Tabasco-Comalcalco province was discovered in 1972 with the Cactus-1 and Sitio Grande-1 wells; it covers an area of 13,100 square kilometers and it mostly produces light oil and its reservoirs correspond to calcareous rocks of the Upper Jurassic and Middle Cretaceous. The Macuspana province extends over approximately 13,800 square kilometers; it is a producer of non-associated gas in reservoirs of the Tertiary age formed by rain delta and platform sandstones, associated with stratigraphic and structural traps. The Sonda de Campeche includes an area of approximately 15,500 square kilometers and it is by far the most prolific in Mexico. The Cantarell complex forms part of this province, together with the Ku-Maloob-Zaap complex, the area s second most important oil-producing field. Most of the reservoirs of the Sonda de Campeche lie in breccias of the Upper Cretaceous to Lower Paleocene age, and in oolitic limestones of the Upper Jurassic. The Litoral de Tabasco province covers an area of approximately 7,400 square kilometers. The 1,500 m N W E S 1,000 m Gulf of Mexico Sonda de Campeche 200 m Litoral de Tabasco Salina del Istmo Chiapas- Tabasco- Comalcalco Macuspana Figure 3.6 Location of the Southeastern Basins. 17

8 Prospective Resources Table 3.5 Prospective resources documented in the Southeastern Basins by hydrocarbon type. Hydrocarbon Type Exploratory Wells Prospective Resources number MMboe Heavy Oil 53 1,076 Light Oil 284 3,508 Superlight Oil 209 2,648 Dry Gas Wet Gas Total 629 8,186 reservoirs are fractured Cretaceous limestones that mostly produce superlight oil. The Southeastern Basins have a cumulative production of 40,685 million barrels of oil equivalent, and remaining reserves of 23,290 million barrels of oil equivalent. The total prospective resource is 16,700 million barrels of oil equivalent, of which 8,186 million barrels have been documented, which means 49 percent of the potential recorded in 629 exploratory opportunities; the remaining 51 percent is in the process of being documented, Table 3.5. Gulf of Mexico Deepwater Basin This is the portion of the Gulf of Mexico Basin that is at water depths exceeding 500 meters and it covers an area of approximately 575,000 square kilometers. Based on the information acquired so far, nine geological provinces distributed over three exploratory projects have been identified: Golfo de México B, Golfo de México Sur, and Área Perdido, Figure 3.7. Some of the geological characteristics are: Perdido Folded Belt dipping under the allochthonous salt strip, a folded and faulted belt was formed as a result of salt settlement and gravitational displacement over the top of Jurassic salt cap that involves the Mesozoic sequence. These structures seem to be cored by salt and are elongated, very big (more than 40 kilometers) and close together. This belt lies at water depths of 2,000 to 3,500 meters. Recently a consortium of various companies drilled a well on the US side of the area known as Alaminos Canyon in the northern protrusion of the folded belt that, according to some sources, found hydrocarbons. Oil is the hydrocarbon type most expected, and the storage rocks would be deepwater fractured limestone in the Mesozoic column, and siliciclastic turbidities in the Tertiary. The Mexican Ridges province is characterized by the presence of elongated folded structures, whose axes lie north-south. The origin is related to gravity slippage of the sedimentary cover. These structures correspond to the southward extension of the Mexican Ridges folded belt, which are associated with a regional uplift located in the Eocene clay sequence. The most important potential hydrocarbons in the sector are gas and possibly superlight oils. In the Saline province of Deep Gulf (Salina del Istmo Basin), the Mesozoic and Tertiary sedimentary column has been highly affected by the presences of large salt canopies and deep-rooted saline intrusions that cause deformation and in some cases a rupture of the Mesozoic and Tertiary structures, which played an active role in the sedimentation, giving rise to the formation of mini-basins caused by salt evacuation where the Pliocene sediments are confined, which make it possible to reach stratigraphic traps. This sector of the Salina del Istmo Basin has lots of evidence supporting the 18

9 Hydrocarbon Reserves of Mexico N W E S Geologic Provinces: 1. Rio Bravo Delta 2. Allochthonous Salt Strip 3. Perdido Folded Belt 4. Distensive Lane 5. Mexican Ridges 6. Saline Basin of Deep Gulf 7. Edge of Campeche 8. Veracruz Canyon 9. Abyssal Plain Km Figure 3.7 Geological provinces identified in the Gulf of Mexico Deepwater Basin. presence of oil that is being squeezed up to the seafloor through faults. This evidences lead to the expectation of mostly light oil hydrocarbons in the sector. The southern-eastern and eastern end of the area contains part of the compressive tectonic front that generated the most important producing structures in the Sonda de Campeche (Reforma-Akal folded belt), with a prevalence of low angle reverse faults lying in a northwestern-southeastern direction and whose transport direction is to the northeastern. Furthermore, the Tertiary sedimentary cover in this zone tends to be thinner, while the Mesozoic structures are relative shallower, which means that heavy oil is especially expected. Well drilling started at the beginning of 2004 in the Gulf of Mexico B project where eight exploratory wells have been drilled to date, and the following have been successful: Nab-1, extra-heavy oil producer and the Noxal-1, Lakach-1 and Lalail-1 non-associated gas wells, Figure 3.8. Jointly, these wells added a total reserve of 548 million barrels of oil equivalent. The prospective resources studies carried out in this basin indicate that it has the highest oil potential, with an estimated mean prospective resource of 29,500 19

10 Prospective Resources Lakach-1 Noxal-1 Leek-1 Tabscoob-1 Pleistocene Pliocene Middle Miocene Lower Miocene Figure 3.8 Representative seismic section of the Lakach-Noxal area of the Gulf of Mexico. million barrels of oil equivalent, which accounts for 56 percent of the country s total, that is, 52,300 million barrels of oil equivalent. at 300 million barrels of oil equivalent, of which 271 million barrels of oil equivalent have been documented with 16 heavy oil exploratory opportunities. Of the total prospective resource estimated for this basin, 7,222 million barrels of oil equivalent have been documented and recorded in 126 exploratory opportunities, which means 24 percent of the potential; the remaining 76 percent has yet to be documented, Table 3.6. Yucatan Platform This province, with an approximate area of 130,000 square kilometers is formed by sediments developed on a calcareous platform, where the geological-geophysical studies and the information of the subsoil have made it possible to establish an active oil system; nevertheless, the prospective resource has been estimated 3.2 Prospective Resources and Exploratory Strategy The knowledge currently available about the geographic distribution of Mexico s prospective resources has made it possible to direct the exploratory strategy towards the search for oil, without neglecting the search for non-associated gas in accordance with the economic value and/or hydrocarbon volumes estimated for all of the basins. Exploratory activities will therefore be mostly focused on the Southeastern Basins, which are traditional oil producers, where oil production is expected to continue in the short and medium term. In the same period, Table 3.6 Prospective resources documented in the Gulf of Mexico Deepwater Basin by hydrocarbon type. Hydrocarbon Type Exploratory Wells Prospective Resources number MMboe Heavy Oil Light Oil 91 5,143 Dry Gas Wet Gas 12 1,183 Total 126 7,222 20

11 Hydrocarbon Reserves of Mexico the Burgos and Veracruz basins will make a sizeable contribution to the production of non-associated gas. Additionally, exploratory works have been programmed in the Gulf of Mexico Deepwater Basin where the highest volumes of hydrocarbons are also expected to be discovered, albeit with a higher risk factor. Due to the above, it is estimated that the basin will make a significant contribution to oil and gas production in the medium and long term. In order to reach these production objectives, the exploratory strategy considers the addition of an average prospective resource of 6,300 million barrels of oil equivalent over the next five years, and to reach a total reserves replacement rate of 100 percent by the year Gas projects: focused on maintaining the production platform for this kind of hydrocarbon and helping reach the reserve replacement goals. The activities will mostly be centered on the Burgos and Veracruz basins. Furthermore, the development of the non-associated gas reserves discovered in the Holok area of the Gulf of Mexico Deepwater Basin will be consolidated. Reaching the above goals is based on the efficient execution of the activities programmed, where the acquisition of information, processing of seismic data and the geological-geophysical interpretation will make it possible to identify new opportunities and generate exploratory locations, as well as to assess the geological risk associated with these, and thus strengthen the portfolio of exploratory projects. In this context, the exploratory drive will be aligned with the following strategies in the next few years: Oil projects: focused on the Southeastern Basins in order to add oil and gas reserves as of 2010 and to intensify the exploration of the Gulf of Mexico Deepwater Basin, without neglecting the rest of the basins. This will support the activities aimed at maintaining the current production platform and reaching the reserve replacement goal. Considerations Given the nature of the exploratory projects, the estimation of the prospective resources is an ongoing activity that calls for the incorporation of results from exploratory wells drilled, and the geologicalgeophysical information acquired. Consequently, the characterization of Mexico s oil potential must be updated as new information is obtained or new technologies are applied. 21

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