ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00738.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

A new plate reconstruction has enabled the Island of Socotra, currently located in the Gulf of Aden adjacent to the Somalian coast, to be restored confidently to its original spatial position adjacent to the southern Omani coastline. Regional geological and geophysical evaluations integrated with this plate reconstruction have confirmed the presence of an untested Mesozoic graben, which trends across the Socotra Platform. Fieldwork carried out in the region now enables a SE extension of the prolific Lower Cretaceous Qishn “play” (delineated in the Masilah Basin, onshore Yemen) to be postulated offshore into the Gulf of Aden.Following the award to British Gas E&P Ltd of a tract of offshore acreage adjacent to the Island of Socotra, exploration studies have confirmed the presence of the Qishn “play” both on the Island of Socotra, and offshore in the one available control well. This work has also identified two additional “plays”: the Shuaiba‐equivalent carbonates, which are prolific producing reservoirs in Central Oman; and the Permo‐Triassic clastics, which may provide a new reservoir target for the region.Ongoing multidisciplinary studies, integrating the results of a detailed geophysical interpretation with high‐resolution structural‐stratigraphic studies, have confirmed the presence of large structures within an undrilled Mesozoic rift‐basin, which will

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00739.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Recent commercial discoveries offshore Palawan have propelled the Philippines into the list of oil‐ and gas‐producing countries, and have focussed on the importance of Miocene reefs as reservoirs. This new situation has motivated the update of earlier depositional‐diagenetic models for the Miocene reefs in the Visayan Islands, which is presented in this paper. These reefs consisted of an association of corals, red algae, bryozoans, and encrusting foraminifers, which formed wave‐resistant, constructed, barrier‐and‐atoll systems along the edge of narrow shelves, with associated back‐reef patch reefs and frontal pinnacle reefs. The latter also grew on structural and depositional highs and plaforms among deeper water carbonate mudstones and shales.Reservoirs developed in all the various types of buildups by extensive burial dissolution, often preceded (with the exception of some pinnacle reefs) by subaerial exposure generating secondary porosity by vadose to phreatic undersaturated dissolution. Seals were generally provided by overlying basinal carbonate mudstones and shales, and by andesitic volcaniclastics and basaltic lava flows. Source beds were mature, basinal, bituminous carbonate mudstones and shales, and migration of hydrocarbons was mainly updip, complicated by local structur

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00740.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Part I of this paper (Journ. Petrol. Geol. 17, no. 4, pp. 429–444, hereafter referred to as Reed, 1994a) discussed the deformation and distribution problems presented by the thick Callovian salt found in the Gulf of Mexico Basin, and the enigma it presents to explorationists studying the area. Attempted solutions for the problems were discussed, together with reasons why these solutions have generally not been successful. A radical, new model was presented that would answer most of the salt problems; this model entails continuous rifting in the Gulf from Late Cretaceous to Recent times. This would imply that the Gulf of Mexico is a tectonically‐active basin, in contrast to the more widely accepted passive‐basin theory. This concluding section of the paper discusses evidence from the Gulf which supports the active‐basin

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00741.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

A total of only six exploration wells have been drilled in Lebanon since World War II. The exposed succession consists predominantly of competent carbonates, with only minor occurrences of shales and marls. None of these wells penetrated formations older than the oldest exposed at the suflace, which are of Liassic age. In the majority, reservoirs were invaded by meteoric waters as a result of the proximity of elevated, outcropping recharge areas, inencient seals, or the proximity of major faults. Calculations based on gravity data indicate that the basement beneath the Lebanon uplift is some 3 km below sea level, providing for a sedimentary column over 5,000‐m thick below the Upper Jurassic, most of which is unknown.The Triassic successions in the adjacent Palmyride Basin of Syria and of northern Jordan are, by contrast, well‐known from subsuflace exploration and drilling; over 1,500 m of carbonates, with thinner interbeds of shales and evaporites, are present in the former, where a number of Triassic oil, gas and condensate discoveries have been made. The axis of the Palmyride Basin trends WSW, towards Lebanon, as revealed by isopachs; Upper Triassic (Carnian) evaporites, including major salts, have a similar trend. It has long been proposed that if Triassic evaporites extend to Lebanon, they may provide a major impervious seal between meteoric water‐invaded reservoir strata above, and potentially petroliferous Triassic and Paleozoic successions below.The recent marine reflection‐seismic survey offshore Tripoli (northern Lebanon) has revealed the presence of a deeper and tectonically‐ mobilised salt level, in the core of a compressional structure, directly on trend with the westwards prolongation of the Palmyride salt and peripheral anhydrite basin on the other side of the Levant (Dead Sea) transform fault (lateral slip here<20 km). It has given added credence to the speculative presence of evaporites 650m below the oldest (Liassic) exposures at Nahr Ibrahim, north of Beirut, which were interpreted from an earlier electrical survey.A regional seal in the subsurface of Lebanon is thus assured, and the ingredients for Triassic, hydrocarbon generation, migration, entrapment and preservation can now be regarded as present. Both offshore (deep) and onshore (more shallow) prospects of Triassic age therefore seem attractive. Additionally. well‐penetration and seismic data from Syria indicate the presence of Ordovician andd Silurian successions at least under northern Lebanon. These successions regionally include several organic‐rich source levels. and lie within reach of the drill on the large onshore structures of the Lebanon uplift.A second, east‐west trending, basin of Triassic age (the Hawran Basin) extends under the basalt areas of Jaba1 Druze (Jabal al Arab) in southern Syria and northern Jordan, and into the Risha “panhandle” (NE Jordan), offering a front

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00742.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The present classification systems of kerogens have many shortcomings, especially in respect of amorphous kerogens which have, so far, remained undifferentiated in relation to hydrocarbon generation. Hence, a practical classification method based on density separation, elemental composition and optical characteristics, which discriminatingly identifies kerogens with indications of their hydrocarbon potential, has been developed.The method first divides the whole range of kerogens into liptinite and humic groups. The liptinitic kerogens are subdivided into Hyperliptinites (prolific oil sources); Mesoliptinites (which are oil‐prone); Metaliptinites (gas‐prone); and Hypoliptinites (having no potential for hydrocarbons). The humic kerogens are similarly divided into subgroups consisting of Hyperhumics (with some gas potential); Mesohumics (mainly gas sources); and Hypohumics (organic materials with no potential for hydrocarbon generati

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00743.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00744.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00745.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00746.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00747.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY