29/10/2020
Oil, geology, and changing concepts in the Southwest Philippines (Palawan and the Sulu Sea)
by: E.F. DURKEE
Ste 7B-LPL Towers 112 Legaspi Street
Legaspi Village, Makati Metro Manila, Philippines
Published 1993.....Corpus ID: 131596053
Geology:
The Southwest Philippines; Palawan, its offshore shelves, Reed Bank, and the southwestern Sulu Sea encompass 350,000 km2 (126,000 mi2). This region contains the better areas to search for significant oil and gas deposits in the Philippines. The two largest oil fields yet found in the Philippines were discovered and confirmed in 1991-1992. West Linapacan field has more than 100 million barrels of recoverable oil. In June 1992, Shell Oil is reported in the Philippine press to have identified the possible occurrence of a 200 to 400 MMBO field at Camago-Malampaya about 30 km southwest of West Linapacan. The Southwest Philippines' oil producing trend, about 40 km off the northwest coasts of Palawan and Busuanga is a northerly trending belt 200 km in length. Oil reservoirs in the Philippine fields are Oligocene to Lower Miocene platform limestones, reefs, and both silicic and carbonate turbidite sequences.
Shared July 26, 2020
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Oil, geology, and changing concepts in the Southwest Philippines (Palawan and the Sulu Sea)
E.F. DURKEE Ste 7B-LPL Towers 112 Legaspi Street
Legaspi Village, Makati Metro Manila, Philippines
Published 1993.....Corpus ID: 131596053
Abstract: The Southwest Philippines; Palawan, its offshore shelves, Reed Bank, and the southwestern Sulu Sea encompass 350,000 km2 (126,000 mi2). This region contains the better areas to search for significant oil and gas deposits in the Philippines.
The two largest oil fields yet found in the Philippines were discovered and confirmed in 1991-1992. West Linapacan field has more than 100 million barrels of recoverable oil. In June 1992, Shell Oil is reported in the Philippine press to have identified the possible occurrence of a 200 to 400 MMBO field at Camago-Malampaya about 30 km southwest of West Linapacan.
The Southwest Philippines' oil producing trend, about 40 km off the northwest coasts of Palawan and Busuanga is a northerly trending belt 200 km in length. Oil reservoirs in the Philippine fields are Oligocene to Lower Miocene platform limestones, reefs, and both silicic and carbonate turbidite sequences. A 540 km gap occurs between the Philippine production at Nido and the closest oil fields to the southwest in Sabah. Untested prospects and leads are present along the South China Sea coast of Palawan.
The southwest Sulu Sea overlies three poorly explored Tertiary sedimentary-structural basins (Balabac, Bancauan, and Sandakan basins). Geology and oil shows suggest the possible presence of commercial oil fields. Prospects and prospect leads are numerous. One well in the Malaysia sector of the Sulu Sea (Nymphe Norde 1) suggests economic potential.
Deep-water exploration targets (untested reefs and structural traps) are present in the South China Sea offshore Palawan. Large gas-condensate and oil reserves are indicated at Camago-Malampaya in 2400+ feet of water. A test of a major deep water reef prospect, Sarap-1, provided an exploration disappointment in 1991. Other major reef traps (e.g. Cliff Head) in deep water with better source rock association remain to be tested.
Besides economic interest, the Southwest Philippines has been the spawning ground of several concepts and theories about the origin and evolution of the overall region. Some theories and concepts are reviewed. The "Ulugan Bay fault" is disputed and recommended for elimination from future maps based on later field work and offshore geophysical studies. A major redefinition is an alternative.
Two schools of thought on the origin of much of Palawan are reviewed. Was continental crust from the South China Sea area subducted beneath Palawan, or is Palawan a complicated thrust pile composed in part of original crust types and early Tertiary sediments that have been thrust or emplaced to the northwest from the Sulu Sea region?
Some future exploration areas, plays, and prospects are illustrated.
INTRODUCTION...
Geology
The Southwest Philippines; Palawan, its offshore shelves, Reed Bank, and the southwestern Sulu Sea encompass 350,000 km2 (126,000 mi2). This region contains the better areas to search for significant oil and gas deposits in the Philippines. The two largest oil fields yet found in the Philippines were discovered and confirmed in 1991-1992. West Linapacan field has more than 100 million barrels of recoverable oil. In June 1992, Shell Oil is reported in the Philippine press to have identified the possible occurrence of a 200 to 400 MMBO field at Camago-Malampaya about 30 km southwest of West Linapacan. The Southwest Philippines' oil producing trend, about 40 km off the northwest coasts of Palawan and Busuanga is a northerly trending belt 200 km in length. Oil reservoirs in the Philippine fields are Oligocene to Lower Miocene platform limestones, reefs, and both silicic and carbonate turbidite sequences. A 540 km gap occurs between the Philippine production at Nido and the closest oil fields to the southwest in Sabah. Untested prospects and leads are present along the South China Sea coast of Palawan. The southwest Sulu Sea overlies three poorly explored Tertiary sedimentary-structural basins (Balabac, Bancauan, and Sandakan basins). Geology and oil shows suggest the possible presence of commercial oil fields. Prospects and prospect leads are numerous. One well in the Malaysia sector of the Sulu Sea (Nymphe Norde 1) suggests economic potential. Deep-water exploration targets (untested reefs and structural traps) are present in the South China Sea offshore Palawan. Large gas-condensate and oil reserves are indicated at Camago-Malampaya in 2400+ feet of water. A test of a major deep water reef prospect, Sarap-1, provided an exploration disappointment in 1991. Other major reef traps (e.g. Cliff Head) in deep water with better source rock association remain to be tested. Besides economic interest, the Southwest Philippines has been the spawning ground of several concepts and theories about the origin and evolution of the overall region. Some theories and concepts are reviewed. The "Ulugan Bay fault" is disputed and recommended for elimination from future maps based on later field work and offshore geophysical studies. A major redefinition is an alternative. Two schools of thought on the origin of much of Palawan are reviewed. Was continental crust from the South China Sea area subducted beneath Palawan, or is Palawan a complicated thrust pile composed in part of original crust types and early Tertiary sediments that have been thrust or emplaced to the northwest from the Sulu Sea region? Some future exploration areas, plays, and prospects are illustrated.
PETROLEUM OCCURRENCE - skipped
GEOLOGIC CONCEPTS; THEIR EVOLUTION, REVIEW, CHANGES - skipped
OIL, GEOLOGY, AND CHANGING CONCEPTS IN THE SOUTHWEST PHILIPPINES 261 of 200 to 400 MMBO at the latter.
Other world class-sized prospects remain to be tested offshore Palawan, in the Sulu Sea basins and in other parts of the Southwest Philippines including the Mindoro, Reed Bank, and Cuyo platform areas.
Image below: Figure 22. Oil and gas fields; wells with important oil and gas shows; or surface hydrocarbon occurrences of note relative to the Southwest Philippines. Published in 1993.
Oil, geology, and changing concepts in the Southwest Philippines (Palawan and the Sulu Sea) @ https://www.semanticscholar.org/paper/Oil%2C-geology%2C-and-changing-concepts-in-the-(Palawan-Village/a16d667bde86d42c103f9cd3468bc820f05c2d91/figure/17
SUMMARY OF NEW AND CHANGING CONCEPTS:
New or changing concepts with respect to the geology and search for oil in the Southwest Philippines are:
1. The area contains world class oil fields with reserve sizes of 100 to 400 MMBO (million barrels of oil) or larger with major gas condensate reserves of 1.0 to 3.0 TCF.
2. A northwest Palawan subduction zone does not exist. Ramping, overthrusting, and duplex emplacement are more likely responsible for the Island of Palawan, at least the southwest two thirds of the Island (Hinz et al., 1989, p. 728).
3. There is not a major north-south transform fault at illugan Bay (Faure et al., 1989, p. 942; field observations, this writer) separating two types of tectonic plates. This general area might represent the northeast edge of ramping of Sulu Sea - Sabah terrains northward onto the edge of the southward drifting East Asia microplates.
4. Pre-Tertiary oil sources of Cretaceous age are perhaps likely for some of the oil to be found along parts of the Palawan shelf.
5. Reefs, especially deep water features offshore Palawan, probably need to have been associated with pre-Tertiary source rocks and or deeply depressed Tertiary strata to have obtained a hydrocarbon charge.
6. Much reduced lateral movement of segments of the South China Sea plate in Paleogene time versus that which has been published by some
CONCLUSIONS
The Southwest Philippines has all the geological prerequisites to become a major oil producing area. This is demonstrated by the discovery and establishment of production from the West Linapacan field with estimated recoverable reserves of 100 to 200 MMBO.
More recently even the West Linapacan field appears to have a chance of being eclipsed by a still larger potential find at Camago-Malampaya. Press reports suggest a recoverable resource in the range
Shared July 26, 2020
Read more:https://gsm.org.my/products/702001-101009-PDF.pdf
