Complex acid-solvent treatment design and practice for Jurassic-Cretaceous carbonate formation of the Varadero oilfield (the Republic of Cuba)

Introduction …………………………………………………………………………………… 1 Geologic Evolution of the northern Caribbean area …………………………………………… 1 Late Triassic to Middle Jurassic Rifting …………………………………………………… 4 Opening of the Gulf of Mexico in the Late Jurassic ……………………………………… 7 Opening of the Proto-Caribbean Ocean Basin …………………………………………… 7 Movement of the Caribbean Plate ………………………………………………………… 8 Collision of Cuba Arc-Forearc with the Bahama Platform ………………………………… 9 Tectonic Summary ………………………………………………………………………… 9 Jurassic-Cretaceous Composite Total Petroleum System …………………………………… 16 Source Rocks …………………………………………………………………………… 16 Lower to Middle Jurassic Rift-related Mudstones …………………………………… 16 Upper Jurassic-Lower Cretaceous Deep-Marine Carbonates ……………………… 18 Upper Cretaceous Deep-Marine Carbonates and Mudstones ……………………… 18 Paleogene Mudstones ………………………………………………………………… 19 Summary of Cuban Oil Geochemistry ………………………………………………… 19 Petroleum Generation …………………………………………………………………… 20 Petroleum Migration ……………………………………………………………………… 21 Significance of the DSDP Site 535 well, southeastern Gulf of Mexico …………………… 21 Significance of the Doubloon-Saxon #1 well, Bahama Platform ………………………… 23 Summary-Jurassic-Cretaceous Composite Total Petroleum System …………………… 24 Geologic Definition of Assessment Units ……………………………………………………… 25 North Cuba Fold and Thrust Belt AU ……………………………………………………… 25 North Cuba Foreland Basin AU …………………………………………………………… 32 North Cuba Platform Margin Carbonate AU ……………………………………………… 32 Assessment of Undiscovered Oil and Gas Resources ………………………………………… 34 Geologic Models for Assessment ………………………………………………………… 34 North Cuba Fold and Thrust Belt AU ……………………………………………………… 35 North Cuba Foreland Basin AU …………………………………………………………… 35 North Cuba Platform Margin Carbonate AU ……………………………………………… 35 Assessment Methodology ………………………………………………………………… 35 Assessment Input Data …………………………………………………………………… 36 North Cuba Fold and Thrust Belt AU ………………………………………………… 36 North Cuba Foreland Basin AU ……………………………………………………… 37 North Cuba Platform Margin Carbonate AU ………………………………………… 39 Assessment Results ……………………………………………………………………… 39 Conclusions …………………………………………………………………………………… 40 References Cited ……………………………………………………………………………… 41 Appendix 1. Assessment input data for North Cuba Fold and Thrust Belt AU ………………… 46 1. Locations of Cuba, Yucatan Platform, Yucatan Basin, Florida Peninsula, Bahama Platform, and the general bathymetry of parts of the Gulf of Mexico, Yucatan Basin, Cayman Trough, Caribbean Sea, and Atlantic Ocean ………………………… 2. Physiographic features of northwestern Cuba and southeastern Gulf of Mexico ……… 3. Locations of onshore oil fields of northwestern Cuba …………………………………… 4. Interpretation of the tectonostratigraphic units of northern Cuba ……………………… 5. Map and schematic cross section showing general positions of tectonostratigraphic units of central Cuba ………………………………………………………………… 6. Stratigraphic column showing repetition of thrust sheets in the Cuban fold and thrust belt in northern Cuba ………………………………………………………………… 7. Lithostratigraphic column for northwestern Cuba and offshore showing reconstructed stratigraphy of the proto-Caribbean basin …………………………………………… 8. Reconstruction of paleogeographic elements in the western Caribbean region during Middle Oxfordian time ………………………………………………………………… 9. Reconstruction of paleogeographic elements in the Caribbean region during Tithonian time ………………………………………………………………………… 10.Reconstruction of paleogeographic elements in the Caribbean region during Hauterivian-Barremian time …………………………………………………………… 11.Reconstruction of paleogeographic elements of the Caribbean region during Late Maastrichtian time …………………………………………………………………… 12. Reconstruction of the Guaniguanico terrane along the Yucatan margin and the development of the active margin west of the El Pinar fault zone of northwestern Cuba …… 13.Correlation of stratigraphic units of the Guaniguanico terrane as it developed along the eastern margin of the Yucatan Platform ………………………… 14.Reconstruction of the position of the Caribbean plate relative to the proto-Caribbean plate in the Early Paleocene …………………………………………………………… 15.Structure of the Yucatan Basin during Paleogene time ………………………………… 16.Map showing a reconstruction of structural features in the western Caribbean region during Middle Eocene time.…………………………………………………………… 17.Tectonic model for the development of the Cuban fold and thrust belt and foreland …… 18. Sequential development of the northwest Cuban fold and thrust belt and the foreland associated with the fold belt ………………………………………………… 19.Chart showing chronology of major tectonic events affecting the northwest Cuba area and the main elements of the Jurassic-Cretaceous Composite Total Petroleum System …… 20.Present-day distribution of synrift Jurassic source rocks ……………………………… 21.Present-day distribution of Upper Jurassic deep-water carbonate source rock ……… 22. Present-day distribution of Lower Cretaceous deep-water carbonate source rocks …… 23.Postulated present-day distribution of Cenomanian-Turonian source rocks …………… 24.Geochemical classification of Cuban oil families ……………………………………… 25.Map of western Cuba showing distribution and classification of three main oil families … 26.Plot of percent sulfur and API gravity for some Cuban oils (from Magnier and others, 2004) …………………………………………………………… 27.Plot of Rock-Eval data in Cuban onshore source rock samples and samples from Deep Sea Drilling Project well 535 …………………………………………………………… 28.Plot of geochemical depositional-source indicators (gammacerane and hopane) showing the general separation of Jurassic and Cretaceous deep-water carbonates with Tertiary siliciclastic source rocks ……………………………………………………… 29.Boundaries of the Jurassic-Cretaceous Composite Total Petroleum System and the three assessment units defined in this study ………………………………………………… 30.Seismic profiles and offshore DSDP well locations northwest of Cuba ………………… 31.Stratigraphic column showing interpretation of carbonate sequences cored at DSDP Site 535 ……………………………………………………………… 32.Modified van Krevellen diagram for potential hydrocarbon-bearing source rocks at DSDP Site 535 ………………………………………………………………………… 33.Stratigraphic column showing positions of oil-stained intervals in DSDP Site 535 core … 34.Map showing locations of oil and gas exploration wells in the southwestern part of the Bahama Platform ……………………………………………………………………… 35.Cross section of wells drilled and tested in the Bahama Platform ……………………… 36.Map showing boundaries of the three assessment units defined in the Jurassic-Cretaceous Composite Total Petroleum System …………………………… 37. Schematic structural cross section of the North Cuba Basin showing general boundaries of the three assessment units defined in the Jurassic-Cretaceous Composite Total Petroleum System …………………………………………………………………… 38.Boundary of the North Cuba Fold and Thrust Belt Assessment Unit …………………… 39.Schematic geologic cross section across onshore northwestern Cuba ………………… 40.Schematic geologic cross section illustrating the complex structure of the Cuban fold and thrust belt and the underlying rift zone, and the definition of exploration play types … 41.Two selected seismic sections showing general expression of the Cuba fold and thrust belt, foreland, and margin of the carbonate platform ………………………………… 42.Structural cross section of the Boca de Jaruco oil field in northern Cuba ……………… 43.Map and structural cross section of the Punta Allegre oil field, northern Cuba ………… 44.Geologic model for assessing undiscovered resources in the North Cuba Basin ……… 45.Composite petroleum-system events chart for North Cuba Fold and Thrust Belt Assessment Unit ……………………………………………………………………… 46.Boundary of the North Cuba Foreland Basin Assessment Unit ………………………… 47.Composite petroleum system events chart for the North Cuba Foreland Basin Assessment Unit ……………………………………………………………………… 48.Boundary of the North Cuba Platform Margin Carbonate Assessment Unit …………… 49.Paleoenvironmental map showing the distribution of platform margin reefs and deep water calcareous sediments during Albian time ……………………………………… 50.Petroleum system events chart for the North Cuba Platform Margin Carbonate Assessment Unit ……………………………………………………………………… 51.Plot showing oil-field size versus discovery year for the North Cuba Fold and Thrust Belt Assessment Unit ………………………………………………………………… 52.