THE NW SULU SEA BASIN, PHILIPPINES : AN ATTRACTIVE FRONTIER AREA FOR PETROLEUM
http://www.doe.gov.ph/ER/archives/win_opp/cd/POBLETE/nw_sulu_sea_basin.htm
Ricardo G. Poblete, Jr. and Arturo A. Morado, Jr.
COMEXCO, Incorporated
The NW Sulu Sea Basin is probably the most attractive frontier area for exploration in the Philippines. It is located within the continental North Palawan Block (NPB), a rifted fragment of the Asian mainland. The Northwest Palawan Area (NWPA), the only petroleum-producing province in the Philippines, is also located within the NPB and to the northwest of the NW Sulu Sea Basin. Previous work and our own recent study suggest that the NW Sulu Sea Basin could contain a petroleum system that is analogous to that of the NWPA.
Numerous large to giant-sized leads, representing the four (4) major play types that are identified in the basin, are presented. The major play types are:
- anticlines with four-way dips;
- Early Miocene carbonates;
- Middle Miocene carbonates; and,
- Miocene turbidites.
Geological conditions in the relatively unexplored NW Sulu Sea Basin present possibilities for major oil and/or gas accumulations. The similar distance to the market in Luzon of the NW Sulu Sea Basin and the giant Camago-Malampaya Gas Field, currently under development by Shell (gas-to-power) in the deep waters of NWPA, implies that even a gas accumulation from the giant leads in the NW Sulu Sea Basin can be a viable economic venture. The variety of the types of leads in both shallow and deep waters in the area present the explorers with medium risk-high reward to high risk-high reward exploration opportunities.
The NW Sulu Sea Basin is part of the greater NW Sulu Sea area that includes the Cuyo Platform and the Cagayan Ridge (Figure 1). The sharp change in the bathymetry near the latitude of 10o30’ North is considered the geographic boundary between the Cuyo Platform and the NW Sulu Sea Basin. The Cuyo Platform is in shallow waters (<200>
Our studies of the NW Sulu Sea Basin in the last three years has led to the following findings that:
There are indications that the hydrocarbon play concept that proved successful in the NWPA might also be present in the NW Sulu Sea Basin;
It contains a variety of untested plays with several giant leads, and;
The area offers an opportunity for both a relatively medium risk-high reward to high risk-high reward exploration venture.
A significant portion of the NW Sulu Sea Basin and the Cuyo Platform is currently under license or under an exclusive Geophysical Survey and Exploration Contract (GSEC) application by South China Resources, Inc. with the Philippine Department of Energy (cf. Fig. 1).
The table below summarizes the highlights of past and present exploration in the NW Sulu Sea Basin and adjoining areas:
Table 1: Geochronological Summary of Past Exploration
Year | Activity | Company/Organization | Purpose |
1969 | Aeromagnetic Survey – Project MAGNET | U.S. Naval Oceanographic Office; Philippine Bureau of Mines and Bundesanstalt fuer Bodenforschung (Bfb) of Germany | Scientific Research |
1970 | Seismic Acquisition | Phil. Overseas Drilling | Petroleum Exploration |
1970 | Seismic Acquisition | Philex Mining Corp. | Petroleum Exploration |
1970 | Seismic Acquisition | Baguio Gold Mining | Petroleum Exploration |
1970 | Sesimic Acquisition | Oriental Petroleum | Petroleum Exploration |
1971 | Seismic Acquisition | Mobil Oil (US) | Petroleum Exploration |
1974 | Seismic Acquisition | Oceanic Minerals (US) | Petroleum Exploration |
1974 | Seismic Acquisition | Brascan Resources (US) | Petroleum Exploration |
1976 | Seismic Acquisition | MultiNatural Resources | Petroleum Exploration |
1977-87 | Seismic, Gravity and Magnetic Acquisition; Ocean Drilling Program | German Federal Institute for Geosciences and Natural Resources (BGR) | Scientific Research |
1978-79 | Seismic Acquisition | Cities Service (US) | Petroleum Exploration |
1978-80 | Seismic Acquisition | Phillips Petroleum (US) | Petroleum Exploration |
1979-81 | Exploratory Drilling – Roxas-1; Dumaran-1 & Paly-1: all dry holes, except Dumaran-1 | Cities Service (US) | Petroleum Exploration |
1980-82 | Seismic Acquisition & Field Geology | Seafront Petroleum | Petroleum Exploration in the Cuyo Platform |
1980-82 | Seismic Acquisition & Field Geology | Phil. Oil & Geothermal Energy (POGEI) & Lepanto Mining | Petroleum Exploration in the Cuyo Platform |
1982-86 | Comprehensive Basin Evaluation Studies | World Bank-funded: Phil. Bureau of Energy Dev’t, Robertson Research & Flower, Doery and Associates. | Petroleum Exploration |
1985 | Geological Field Studies in Central Palawan | UNDP-Phil. Bureau of Mines | Mineral Resources Evaluation |
1992-94 | Seismic, Gravity, Magnetic & Geochemical Data Acquisition; Seismic Reprocessing; Basin Evaluation Studies | Australian Geological Survey Organization (AGSO) & Phil Dept. of Energy | Petroleum Exploration |
1996-98 | Data Re-Interpretation & Basin Evaluation | South China Resources & COMEXCO, Inc. | Petroleum Exploration |
1996-Present | Seismic Reprocessing; Aerogravity and Magnetic Acquisition; Seismic Acquisition | Murphy Oil (US) & South China Resources | Petroleum Exploration in the Cuyo Platform |
3.1 Tectonic Setting and Present Structure
The NW Sulu Sea Basin, together with the Cagayan Ridge to the east and the Cuyo Platform to the north, is located within the continental NPB (Figure 2 ). The continental basin is bounded to the west by the uplifted North Borneo-Palawan ophiolite province and to the east-southeast by the oceanic SE Sulu Sea Basin and the Sulu-Negros Trench. A submerged portion of the ophiolite province presently underlies the northwestern margin of the NW Sulu Sea Basin shelfal area.
The Cagayan Ridge is a southeast-facing continental volcanic arc of ?Oligocene-Miocene age. It is a partly submerged magmatic arc that separates the continental basin of NW Sulu Sea from the oceanic SE Sulu Sea basin (Figure 3). The petrology (Kudrass et al., 1990 in Hinz et al., 1991) and geochemistry (Spadea et al., 1991 in Hinz et al., 1991) of samples collected from drillsite 771 during the Ocean Drilling Program (ODP) Leg 124 indicate that continental basement underlies the volcanic rocks of Cagayan Ridge (Rangin, 1991). A series of northeast-trending rift half-grabens have also been recognized on seismic below the thick volcanic units (Hinz et. al., 1991). These half-grabens are probably equivalent to those observed in the NWPA and other areas within the NPB.
The uplifted North Borneo-Palawan ophiolite province is a remnant of the Early to Middle Cretaceous oceanic Proto-South China Sea (PSCS) (cf. Fig. 2 ). The PSCS was modeled by Morado and Poblete (1997a) to have progressively thrusted over a portion of the NPB as a result of the nearly coeval opening of the present South China Sea to the north-northwest and the SE Sulu Sea to the southeast (Figure 4a-4d).
Northeast-trending Paleogene extensional features, similar to those in the Northwest Palawan Area (NWPA) and Cuyo Platform, exist in the NW Sulu Sea Basin (Figure 5). The north to northeast-trending en echelon folds, which are very prominent in the deep water portion of the basin, were probably inverted grabens that resulted from compressive or transpressive movement episodes during the Early to Middle Miocene (cf. Fig. 4c and 4d). Some possible igneous extrusions are observed on seismic and these appear to be localized and suspected to have emanated along the margins of the rift faults. An analogous occurrence of volcanic extrusives in the hydrocarbon-producing NWPA was encountered in the Boayan-1 well (cf. Fig. 5).
3.2 Stratigraphic Summary
The stratigraphic development in the basin can be can be segregated into four major stratigraphic sequences: pre-rift, syn-rift, drift-sag and post-drift (Figure 6 ).
The NW Sulu Sea Basin, like the Cuyo Platform and NWPA, is interpreted to be underlain by a thick pre-rift sequence of highly deformed autochthonous Paleozoic to Mesozoic metamorphic and sedimentary materials derived from a continental source similar to the outcrops in north Palawan and the Calamianes Island group. These outcrops reveal similarities with chronostratigraphic lithologies presently found in southern China (Hashimoto and Sato, 1973; Fontaine, 1979; Fontaine et al., 1985; BED, 1986).
The rift phase within the southeastern Eurasian margin, including the NPB, occurred from the close of Cretaceous to Early Oligocene (cf. Fig. 4a and 4b). The rifting event, which led to the development of large horst and grabens, corresponds to the latest phase of the Yenshanian orogeny as recorded on mainland China (Holloway, 1982).
The syn-rift sequence in the NW Sulu Sea Basin is possibly deposited in a shallow marine to marginal marine environment of deposition similar to that of the NWPA as described by Benavidez et. al., (1995). A lacustrine environment could also be present within the basin. Lacustrine sediments were encountered in the Maniguin area (Del Pilar, 1997) on the northeast portion of the NPB. In the PSCS basin (cf. Fig. 4a and 4b), deposits were mainly deep water turbidites of Eocene age (UNDP, 1985) which are represented on outcrops by the widespread Crocker Formation. It has been suspected that sometime in the Early and Middle Oligocene, portions of the eastern margin of the PSCS basin were affected by compressive movements caused by the initiation of spreading in the SE Sulu Sea (cf. Fig. 4a and 4b).
Past workers referred to the syn-rift sequence of the NPB as the pre-Nido Tertiary Formation (Sali and Oesterle, 1981; Phillips Petroleum, 1983). The Lower Paleogene syn-rift sequence is generally absent in the NWPA. The Upper Paleogene, however, is represented by an Upper Eocene trangressive sandstone overlain by an Upper Eocene to Lower Oligocene carbonate platform (Beddoes, 1980 and Hatley, 1980 in Holloway, 1982). In the east Palawan area, shallow marine undifferentiated Eocene limestones are reported to outcrop in a few islands/islets north of Dumaran Island, e.g. Pabellion, Apulit and southeastern Maytiguid Islands (David and Fontaine, 1985). These carbonates could be equivalent to the transgressive Late Eocene Lepitan Limestone in onshore SW Mindoro (Sarewitz and Karig, 1986) on the northeastern extremities of the NPB, where it has been reported to drape over the thick syn-rift sequences. Seismic data in the western part of the Cuyo Platform suggest the presence of at least 2,500 meters of syn-rift sequences in some of the half-grabens.
The recent seismic mapping show that very thick Paleogene syn-rift sequences underlie the NW Sulu Sea Basin. The Lower and Upper Paleogene sequences appear to be separated by a local unconformity of possible Early Eocene age. This deposition break is well-recognized on seismic in the deep water part of the basin. The anticipated syn-rift sequences were probably deposited in a lacustrine to possibly shallow marine environment. It was noted that in the NWPA, some of the oil discovered is sourced from syn-rift deposits (Branson et al., 1997).
The mid-Oligocene Unconformity marked the transition from rift to drift. From Late Oligocene to Middle Miocene, the South China Sea opened (cf. Fig. 4c and 4d) resulting in the southward drift of the NPB to its current position (Taylor and Hayes, 1983). Crustal sagging accompanied this drifting episode. Contemporaneous oceanic spreading in the SE Sulu Sea resulted in compressional folding and local uplifts along the eastern margin of the PSCS basin. This was probably partly compensated by the continued subduction of the southern half of the oceanic crust beneath the Sulu-Negros Trench (Morado and Poblete, 1997a).
The drift-sag sequence is composed of variable deposits of Upper Oligocene to Middle Miocene age. These deposits range from non-marine to lacustrine clastics and shallow to deep open marine carbonates and clastics. Included within this sequence are the Nido Limestone Formation (or its onshore equivalent in Palawan Island, the St. Paul’s limestone) and the Pag-asa Formation, which includes the Galoc Clastics and the Batas Conglomerate.
In the NW Sulu Sea Basin, the drift-sag sediments are anticipated to be generally shallow marine carbonates to transitional marine on the shelf and fault block crests and deep marine on the basin lows, similar to the NWPA. In the Maniguin-2 well, on the northeastern part of the NPB (cf. Fig. 5), the drift-sag sediments are non-marine to lacustrine (Del Pilar, 1997; Morado, 1997). To the northwest of this well towards southwest Mindoro Island, the drift-sag sediments become transitional to deeper marine (BED, 1986). The drift-sag sediments contain the main proven source rocks, reservoirs and seals in the petroleum system of NWPA. In the Maniguin-2 oil discovery, the source, reservoir and seal are within the drift-sag sequence (Del Pilar, 1997).
The Middle Miocene Unconformity, which records the initial collision of the NPB with the Philippine Mobile Belt (PMB), separates the drift-sag sequence and the post-drift sequence
The dominant structural deformation in the NPB during the post-drift phase was compressional resulting in uplift and folding. There was also transpressional reactivation of old rift faults (Branson, et. al., 1997) which resulted in inverted structures. Some of the traps formed during this period are productive in the NWPA (e.g. W. Linapacan, Linapacan A and B).
The post-drift sequence is characterized by the presence of thick coarse clastics, mostly conglomerates, due to uplifts related to compressional and transpressional episodes brought about by continuous collision of the NPB with the Philippine Mobile Belt (PMB). These sediments belong to the Matinloc Formation. In the NWPA, Branson, et. al. (1997) noted that in some parts, uplift was in excess of 1,000 meters. The post-drift phase was followed by the deposition of Plio-Pleistocene biocalcarenites, marls and argillaceous limestones that composed the Carcar Formation.
The tectonic model proposed by Morado and Poblete (1997b) for the continental NPB is the foundation by which the petroleum potential of the NW Sulu Sea Basin has been evaluated. It is our belief that a potential petroleum system, very similar to the one that proved successful in the NWPA, exists in the NW Sulu Sea Basin (Figure 7). In particular, rift fault systems analogous to those that control the petroleum system in the NWPA (cf. Fig. 5) are present in the NW Sulu Sea Basin.
4.1 Source Rocks
None of the three wells in the area (cf. Fig. 2 and Fig. 5) penetrated any potential source rock (BED, 1986). However, the existence of possible source rocks is imlpied by the presence of relatively good gas shows (C1-C4) and dead oil traces in a 1,100 meter thick interval of non-reservoir conglomerates in the Dumaran-1 well drilled by Cities Service in 1980. It is speculated that the hydrocarbons found in this well must have migrated up dip from a source deeper in the basin (Fraser and Guazon, 1995).
Potential hydrocarbon kitchen areas in the basin are large Paleogene grabens with thick syn-rift sediments attaining a thickness in excess of 5,000 meters and overlain by drift-sag sediments of up to 3,000 meters thick (cf. Fig. 6). Syn-rift lacustrine to marginal and shallow marine sediments and drift-sag deep water carbonates and shales, very similar to those in the NWPA are the anticipated source rocks. An older source, possibly Cretaceous in age and possibly similar to the one proposed by Durkee (1992) for the western Palawan shelf, might also be present in the basin.
4.2 Thermal Maturation
Thermal maturation of the sediments in the basin was determined using the Lopatin method (Waples, 1980). Random points along selected seismic dip-lines in the basin were chosen for thermal maturity modeling. Some of these models are presented here (Figures 8a to 8d).
A geothermal gradient factor of 3.92oC/100m (2.15oF/100ft), which is the average of two nearby ‘continental’ wells, Paly-1 and Maniguin A-1X, and ambient surface temperature of 24oC were utilized in the burial history modeling. This geothermal gradient factor is comparatively higher than the prevailing average of 3.6oC/100m in the petroleum-producing NWPA. Moreover, it is apparently higher than those in other rift-sag basins, e.g. the Damintun Depression in North China (3.4oC/100m, according to Xiao & Zuan, 1991).
The mature sediment thicknesses and computed TTI values obtained from the Lopatin models were plotted on the map and contoured for visual interpretation and presentation (Figure 9). The distribution plots appear to correlate well with the predominant north-northeast structuring in the basin (cf. Fig. 5).
From the burial history charts (cf. Fig. 8), the onset of hydrocarbon generation at the base of the syn-rift sediments occurred as early as Late Eocene to Early Oligocene. Thick intervals of the potential syn-rift and drift-sag source rocks contained in the kitchen areas are presently still within the hydrocarbon-generating window.
It was noted from the various thermal maturity profiles across the deep water part of the basin that much of the drift-sag potential marine source rocks are still within the oil generating window stage (between TTI 15 and 160). Some of the syn-rift source are in the gas generating stage. The average top of the oil window in the deep water portion of the basin is approximately 3,500 meters while the average top of the gas window lies at around 4,500 meters.
Up to 5,500 meters thick of thermally mature sediments were determined from the plots of the thermal maturity profiles using time-temperature indices. Two major north-northeast trending belts of potential kitchen areas, measuring approximately 40 kilometers by 80 kilometers (3,200 square kilometers) each, contain at least 3,500 meters of thermally mature sediments (cf. Fig. 9). These potential kitchen areas correspond to the two parallel major grabens in the basin. The areas of these kitchens are considered very large and could supply the necessary volumes for major accumulations in the basin. In comparison, the size of the Malampaya Graben kitchen of NWPA, which is the source for most of the hydrocarbons accumulations in that basin, is approximately 3,000 square kilometers. It is therefore considered that, indeed, the NW Sulu Sea Basin is a very attractive frontier area for exploration.
4.3 Hydrocarbon Migration
Hydrocarbon migration from the source to the trap is anticipated to be via numerous fault and fractures systems and permeable beds present in various stratigraphic levels (cf.Fig. 7). Timing of trap formation is not considered critical in the basin since hydrocarbon generation from potential source rocks continued up to the present day (cf. Fig. 9).
A study by Todd, et. al. (1997) suggests that typical major petroleum provinces in Southeast Asia are characterized by a close association of oil and gas pools to within 20 kilometers of the source kitchen and that outside of this "halo" of accumulations, valid traps tend to be severely underfilled or dry. Most, if not all, of the leads that have been identified in the NW Sulu Sea Basin are within 20 kilometers of the potential source kitchen.
4.4 Reservoir Rocks
The potential reservoir sections in the basin are present in the pre-rift, syn-rift and drift-sag sediments (cf. Fig. 6 and Fig. 7). The pre-rift reservoirs include the Cretaceous sandstones equivalent to those gas-bearing sandstones encountered by the Sampaguita wells in the Reed Bank west of the NWPA and pre-Tertiary fractured basement rocks or carbonates similar to those that are hydrocarbon-bearing in southern Vietnam, North China (Zhai and Zha, 1981; Xiao Guan and Zuan, 1991) and Bohai Gulf (Li, 1986).
The syn-rift reservoirs are probably non-marine to shallow marine sandstones and shallow water carbonates. At the San Martin-1 gas discovery well in the NWPA, the shallow marine Eocene sandstones have porosities up to 21% (BED, 1986). While in the Reed Bank area, west of NWPA, the Sampaguita wells tested substantial amounts of gas from non-marine to transitional Paleocene-Eocene sandstones (BED, 1986). The Late Eocene rocks onshore Mindoro Island have porosities ranging from 7% to 20% with measured permeabilities up to 225 mD (Benavidez, et. al., 1995).
Potential drift-sag reservoirs are very similar to those that produce hydrocarbons in the NWPA (cf. Fig. 7). These reservoirs include shallow water carbonate buildups (Nido Limestone) on highs analogous to the Camago-Malampaya, Nido, Cadlao and Matinloc fields and turbidite sandstones in the lows, similar to the oil-bearing turbidite sandstones at the Galoc and Octon discoveries in the NWPA.
Several possible turbidite canyons have been identified on seismic along the present western margin of the NW Sulu Sea Basin and these could have been the pathways of the turbidites to the basin floor currently located in the present day deep water portion of the basin.
4.5 Seal
The regional top seal of the basin is anticipated to be the drift-sag Early to Middle Miocene fine-grained sequence (cf. Fig. 6 and Fig. 7) that is thick and widespread in the NPB. This sequence is equivalent to the deep water Pag-asa claystone of the NWPA. Local top seals would be provided by intra-formational claystones associated with transitional to shallow water sequences in the syn-rift sediments.
4.6 Trap Formation
The potential traps present were formed mostly during the syn-rift and the drift-sag phases although additional potential traps were formed during the post-drift/collision phase. The timing of trap formation is not considered a problem in this basin since, as mentioned earlier, hydrocarbon generation from potential source rocks continued up to the present day (cf. Fig. 9).
There are four major petroleum plays (Types A to D) in the basin (cf. Fig. 7): They are:
- anticlines with four-way dip closures stacked with Mesozoic to Early Miocene reservoirs (Type A);
- Early Miocene reefs (Types B1 & B2);
- Middle Miocene reefs (Types C1 & C2), and;
- Miocene turbidites (Type D).
Numerous leads, representing the four aforementioned plays, have been seismically identified in the NW Sulu Sea Basin. The locations of these leads are indicated in Figure 10. Note that most of the leads are near the potential source kitchens as previously discussed.
Type A: Anticlines with Four Way Dip Closure
Anticlines with four-way dip closures are the most impressive plays in the basin. These are situated in the present-day deep water portion (>200m subsea). These anticlinal leads were seismically defined on the Top Early Miocene level. These large anticlines are products of transpressional and/or compressional folding during the drift-sag phase (Morado and Poblete, 1997b). The folding created inverted grabens placing both source and reservoirs within the four-way dip closures. These are analogous to the productive structures described by Eubank and Makki (1981) in the Central Sumatra Basin.
Examples of this play are shown in Figure 11a-c. The areal extent of these four way dip closures range between just below 50 to over 600 square kilometers. These closures are indeed giant sizes and they attest to the exciting potential of the basin. Please note also that in the crests of some of these anticlines, possible Middle Miocene carbonate buildup exists (cf . Fig. 11a and 11c), providing for additional targets in this play.
Type B: Early Miocene Carbonate Buildup
Early Miocene carbonate buildup plays (cf. Fig. 7) were developed during the drift-sag phase in the basin. The more dominant carbonate play in the basin is represented by Early Miocene reefs which are equivalent to the main productive trapping mechanism in the NWPA (e.g. Camago-Malampaya, Nido, Cadlao, Matinloc and San Martin). Most of them grew on the original rift highs and near potential mature source rocks that are related to rift grabens. Some of the reefs apparently built up along "shelf breaks", hence, lying directly updip from potential mature source rocks (Morado and Poblete, 1997b).
Selected interpreted seismic sections across some of the carbonate leads are displayed in Figure 12a-c and Figure 12d-e. In many of them, all of the qualities required for reef definition on seismic, eg. mounded form, discontinuous internal reflections, onlap of surrounding sediments and drape of overlying sediments, are seen (Morado and Poblete, 1997b). Hence, their presence in the NW Sulu Sea Basin is unequivocal.
Areal closures of Early Miocene carbonate leads range from 6.5 to 104 square kilometers with vertical reliefs ranging from ~250 to 500+ meters. These size ranges are considered to be large for this type of play and could contain potential giant hydrocarbon accumulations. Most of the Early Miocene carbonate leads are in shallow waters (<200>
Type C: Middle Miocene Carbonate Buildup
Several Middle Miocene carbonate leads have also been mapped. They are indicated on seismic in Figures 11a, 11c and 12b. Their areal extent range between 9.0 and 75 square kilometers with vertical reliefs from ~300 to 1,000 meters. As with the Early Miocene carbonate leads, the Middle Miocene carbonate leads have giant sized volumes. Note that in Figure 12b, the Early Miocene carbonate is overlain by the Middle Miocene carbonate. This geological situation would therefore offer multiple reservoir objectives on this location.
The Middle Miocene reefs either developed directly on top of Early Miocene reefs or on residual highs left by the Early Miocene reefs due to compaction, or on top of Base Middle Miocene Unconformity highs (cf. Fig. 7). Good analogues for the Middle Miocene reefal plays are those found in the Luconia Shoals of Sarawak where several giant gas fields have been discovered, in the North Sumatra Basin, in East Natuna (Terumbu Carbonate) and offshore Danang-Vietnam along the Triton Horst (Murphy, 1997).
Type D: MioceneTurbidites
Basin floor turbidites have been observed from several seismic lines cutting across the deep water part of the NW Sulu Sea Basin. The extent of each turbidite section, however, have not yet been delineated at present. Some sections show thick, multiple stacking of individual turbidite units ranging in age from Early to Middle Miocene. This geological situation would offer multiple target reservoir objectives on this location.
An interpreted seismic section showing a typical Miocene turbidite section in the basin is presented in Figure 13. In the NWPA, the Galoc and Octon field discoveries are fine examples of Miocene turbidite plays. In the Sandakan Basin, in southeast Sulu Sea, similar plays were found to be hydrocarbon-bearing. Miocene turbidites are the current major plays in the SE Asian region, as shown by latest discoveries offshore Kalimantan, offshore Sarawak, etc.
7. Conclusions and Recommendations
Our studies show that the NW Sulu Sea Basin has the potential to be a major petroleum-producing region in this part of SE Asia and the world. It may contain a potential petroleum system that is very similar to the proven petroleum system in the adjoining NWPA. Currently, four major play types have been seismically mapped in the basin.
It is therefore recommended that further and more detailed serious exploration be conducted in the area. Exploration success in the area will depend on the use of new technologies. This view is already supported by the vast improvement of seismic data quality from 1981 to 1994 resulting in a better understanding of the petroleum potential of the east Palawan area in general.
The authors would like to thank South China Resources, Inc., particularly Messrs. Edgardo P. Reyes and David R. Baladad, for granting permission to present and publish this paper. We would also like to thank our colleagues at COMEXCO, Inc. for their contributions particularly in the drafting of the text and figures.
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