bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE ZUBAIR FORMATION, EAST BAGHDAD OILFIELD, CENTRAL IRAQ
Authors: Ali A. Jawad , Aziz Z. R. 
Published: December 2007

A number of depositional cycles have been defined from the Zubair Formation in central Iraq (East Baghdad field). Each cycle represents the growth of a deltaic lobe (construction phase), followed by a hiatus during which the delta margin was subjected to wave and tidal activity (destruction phase), succeeded by a marine transgressive shale by which the cycle was concluded. When the growth of the deltaic lobe is renewed over a shale base, a new cycle begins.For each depositional cycle, four facies were identified from sections of core samples. These are: low‐sinuosity (distributary) channels (facies A); marsh (facies B); chenier (facies C); and shelf (facies D). Facies A. B and C comprise the lobe, i.e. indicate a marine regression, whereas facies D concludes the cycle and indicates a transgression.The sandstones of the Zubair Formation are classified as quartz arenites: they are mineralogically and texturally mature, fine‐ to very‐fine grained, well‐ to moderately‐well sorted, fine‐ to nearly‐symmetrical, skewed and mesokurtic.The rocks of the source area are acidic‐igneous. The source area, located within the Arabian Shield, underwent successive periods of tectonic renewal giving rise to high values of sediment supply, and lower values during intervening periods. The detrital materials supplied were to a large extent recycled.
THE HISTORY OF HYDROCARBONS EXPLORATION AND PRODUCTION IN ARGENTINA
Authors: Yrigoyen M. R. 
Published: December 2007

Sedimentary basins in Argentina cover about 1.4 MM sq. km on land, and 400,000 sq. km offshore as far as the 200‐m isobath. Oil and gas has been produced from six mostly onshore pericratonic basins, all of which belong to the Sub‐Andean domain. Their current daily production amounts to 553,800 brls of oil (of which only 26,500 b/d comes from the offshore) and 2,392 million cu. ft of gas. Currently, proved reserves are around 1,354 million brls of oil and 20.3 trillion cu. ft of gas. Cumulative production to end‐1990 was 5.0 billion brls of oil and 13.7 trillion cu. ft of gas, 93% of which was associated gas.The most important basins from the viewpoint of current oil production are: Neuquén (yielding 44.5% of Argentina's total output); San Jorge (33.2%); Cuyo (9.9%); Magallanes (or Austral) (9.4%) and Tarija/Orán (3%). Yacimientos Petrolíferos Fiscales (the former Argentine State oil agency. YPF) is the largest operator in the country, with about 48% of daily oil and 64% of daily gas production, and the remaining output comes from private companies. However, this balance is expected to change in the near future as a result of deregulation and privatisation policies being implemented by the Government.
DEPOSITIONAL MODELS OF THE LOWER CRETACEOUS QUINTUCO — LOMA MONTOSA FORMATION, NEUQUÉN BASIN, ARGENTINA
Authors: Carozzi A. V. , Orchuela I. A. , Schelotto M. L. Rodriguez 
Published: December 2007

The Quintuco — Loma Montosa Formation is the largest and most diversified oil‐producing carbonate depositional system in the Neuquén Basin. It was mainly deposited during the Early Cretaceous, in an intracratonic embayment of the Andean orogenic belt which extended eastwards over the South American Plate.Microfacies techniques have revealed that this formation consists of a number of juxtaposed, well‐developed depositional environments, which were from west to east: carbonates (basin, slope, and oolitic build‐up, which developed into an oolitic‐bioclastic platform); then evaporites (lagoonal and sabkha, both with frequent meteoric dolomitization).These environments shifted in time through several transgressive‐regressive cycles controlled by eustatism and synsedimentary differential subsidence, which originated in reactivated cratonic structures. At all times, the carbonate‐evaporitic environments were surrounded by fringing fan‐deltas. During regressive episodes, these extended basinwards as fluvial, and fan‐delta plain and front facies, terminating with unusual mixed carbonate — fan‐delta slope deposits.This extremely diversified association of carbonate, evaporite and siliciclastic sediments in the Quintuco‐Loma Montosa Formation overlies the mature, black shales of the Vaca Muerta Formation, which acted as source beds. Each depositional sub‐environment has the possibility of producing oil as a result of various types of secondary burial porosity (preceded in places by intercrystalline porosity produced by meteoric dolomitization), when combined with appropriate tectonic conditions.In this respect, the Quintuco‐Loma Montosa Formation is the largest and most attractive target for oil exploration in the Neuquén Basin.
THERMAL MATURITY AND SOURCE‐ROCK POTENTIAL OF THE SEDIMENTARY SUCCESSION FROM THE DRAKE FIELD, SVERDRUP BASIN, ARCTIC CANADA
Authors: Gentzis T. , Goodarzi F. 
Published: December 2007

The thermal maturity and source‐rock potential of the sedimentary succession in the Drake field, Melville Island, Arctic Canada, have been studied using reflected‐light microscopy and Rock‐Eval pyrolysis. The Mesozoic sediments are immature to mature (% Ro = 0.35‐0.80). Vitrinite reflectance in Cretaceous sediments ranges from 0.35 to 0.56%; in Jurassic sediments, it ranges from 0.40 to 0.66%, and in Triassic sediments, from 0.50 to 0.80%. The Triassic Schei Point Group shales and siltstones contain organic matter of marine origin, whereas the predominantly plant‐derived organic matter present in the Jameson Bay, Ringnes and Deer Bay Formations has higher TOC. Among the Schei Point Group sediments, the Eden Bay Member of the Hoyle Bay Formation has high TOC content (approx. 5.0%) and high HI values (in excess of 600 mg HC/g Corg). It is followed by the Cape Richards Member and the Cape Caledonia Member of the Murray Harbour Formation (approx. 5.0% TOC).Regional variations in the level of thermal maturity of Mesozoic sediments in the Sverdrup Basin are mainly a function of burial depth. Thermal subsidence, uplift, erosion and heat associated with periods of diapiric and igneous intrusions may have been responsible for the thermal maturity pattern in the Drake field. The Jurassic Jameson Bay, Ringnes and Deer Bay Formations are immature to marginally mature, and have limited oil‐generation potential due to their high terrestrial input. The organic matter is these formations has good gas potential.
COAL RANK AND TYPE VARIATION IN ROCK‐EVAL ASSESSMENT OF NEW ZEALAND COALS
Authors: Suggate R. P. , Boudou J. P. 
Published: December 2007

Rock‐Eval and coal analytical data are compared for New Zealand coal samples ranging from peat to medium‐volatile bituminous coal. Most are humic coals within the New Zealand coal band, which is representative of the Type III maturation series defined for kerogens. However, four were chosen as particularly high‐hydrogen coal types. Relations between individual parameters — principally H/C, O/C, Tmax, HI and OI — are generally similar to those of Espitalié et al. (1985, 1986), but important differences include a broader range of HI values in the peats and lignites, and a differentiation between maturation and coal‐type effects in the relationship of HI to H/C. Correlations of the effects of maturation on HI, OI, Tmax and vitrinite reflectance are made by the use of the independent Rank(S) scale of Suggate (1959).Rank(S)/reflectance relations vary between well sequences. The Rank(S) scale is used to integrate biomarker data on hydrocarbon generation and expulsion. The oil zone (“oil window”) corresponds to the range of bituminous coals, beginning at Rank(S) 10 (Tmax425°C) and ending at Rank(S) 17 (Tmax estimated at 550°C). Release of oil begins at or soon after Rank(S) 12.5 (Tmax 435°C), and culminates in the range Rank(S) 14.5‐ 15.5 (Tmax 460–480°C). For the Taranaki Basin, New Zealand, the results imply that a substantially greater volume of coal measures has been subject to oil generation and migration processes than previously thought.
THE RECOVERABLE OIL AND GAS RESOURCES OF MONGOLIA
Authors: Penttila W. C. 
Published: December 2007

The data‐base for this study is mainly unpublished Mongolian and Former Soviet Union reports (1958 to 1989), and studies conducted by or for the Mongol Petroleum Co. (Mongol Gazryn Tos: MGT) (1989 to 1992). A very small amount of data was obtained from published literature. Until 1989, the majority of work on the petroleum geology of Mongolia either condemned the prospects, or suggested that there was only very limited oil and gas potential.However, the present evaluation, which is based on three years' work by the Author and his associates, supported by Mongol Petroleum Co. explorationists, is that three to six billion brls oil‐equivalent (o.e.) of conventional recoverable oil and gas resources within the territory of Mongolia is a reasonable expectation. The expected “most likely” oilfield size ranges from 100 to 170 million (MM) brls o.e., with the “low” oilfield size ranging from 5 to 10 MM brls o.e. and the “high” oilfield size ranging from 330 to 700 MM brls o.e.The concepts upon which these estimates are based were derived from Klemme (1980, 1983, 1986); Klemme and Ulmishek (1991); Ulmishek (1986); and Ulmishek and Klemme (1990).
JORDAN REVISITED: HYDROCARBONS HABITAT AND POTENTIAL
Authors: Beydoun Z. R. , Futyan A. R. I. , Jawzi A. H. 
Published: December 2007

A thick succession of sedimentary rocks, comprising mainly Paleozoic shallow‐marine and fluvial deposits, and Mesozoic and Paleogene marine carbonates, with subordinate elastics and evaporites, occurs in Jordan. These are preserved in several basins, including: Late Paleozoic inverted basins with thick, Infra‐Cambrian to Silurian successions in the south, east and NE; and younger, Late Cretaceous and/or Tertiary basins in the centre and west, in which Mesozoic marine shelf sediments and/or thick, rift‐related Neogene sediments are well‐developed.Two regional, organic‐rich source‐rock levels occur. They comprise Upper Ordovician/ Lower Silurian shales in the SE half of the country, and Upper Cretaceous, bituminous chalky marls in the western/central sectors; the former range from immature in the SW to locally over‐mature in the NE, whereas the latter are mainly immature, except where deeply buried, as in the Jordan Valley/Dead Sea rift and part of the Azraq rift. Subordinate source‐rock levels occur in the Triassic and Middle Cretaceous. Numerous hydrocarbon indications, including seeps and floating asphalt blocks, occur in the Dead Sea area and have been correlated with the Upper Cretaceous source rocks.In spite of these positive indications, only 13 exploration wells have been drilled since drilling first began in the mid‐1950s. The Natural Resources Authority (NRA) has established modest oil and gas production in two fields, mainly through the drilling of well clusters in encouraging areas. Hydrocarbons potential, however, remains good, with play concepts related to the major source levels. Detailed local and regional analytical studies, together with extensive and sophisticated seismic acquisition and processing/reprocessing, are required, however, prior to further drilling, with clear and separate strategies for each of the plays.
PROBABLE CRETACEOUS‐TO‐RECENT RIFTING IN THE GULF OF MEXICO BASIN An answer to Callovian salt deformation and distribution problems? Part 1
Authors: Reed J. M. 
Published: December 2007

Abundant evidence from the Northern Gulf of Mexico Basin suggests that late Early Cretaceous to Recent sea‐floor spreading is the principal factor in the formation of the structural components of this basin. This would classify the Gulf of Mexico Basin as an active tectonic basin as opposed to the more accepted passive basin status. The following two‐part paper presents a model for this lithospheric plate adjustment together with the geological evidence to support this movement. Part 1 discusses the rift model and supporting evidence. Some of this evidence is: a proposed triple‐junction rift zone radiating from a large dome centered in the DeSoto Canyon area; the division of the Gulf of Mexico Basin Jurassic salt province into three salt basins (the Interior, Exterior, and Challenger Basins); the linearity and structurally‐positive attitude of the Cretaceous Shelf Edge; an excessive Exterior Basin salt mass that thickens towards the Sigsbee escarpment; large areas of non‐diapiric salt found within the Exterior Basin; an extensional fault zone found underlying the Abyssal Plain; and the absence of a Late Mesozoic section from the Exterior Basin, a section that would be needed to cover the salt until it was overlain by younger Tertiary sediments.Part 2 discusses further evidence for an active Gulf of Mexico Basin, and includes the following observations. The recorded positive gravity response in the Exterior Basin is in conflict with thick Louann salt found there. Possible lithospheric plate boundaries are outlined by linear magnetic signatures, recorded earthquake epicenters and centers of active and dormant volcanism. Magnetic, deep refraction and reflection data record a ridge‐and‐valley basement complex running parallel to these lithospheric plate boundaries. Refraction and reflection data allows the Challenger salt layer to extend northwards under the Abyssal Plain, and to connect to the Exterior Basin Louann salt layer. Eastern Cretaceous Shelf Edge paleostmctural restoration shows doming along this linear structure from the early Late Cretaceous through the Early Tertiary, which corresponds to Albian‐ early Cenomanian through Early Tertiary linear doming in the offshore area of eastern Mexico. Eastern Mexico's Tuxlas volcanic field appears to be part of the Trans‐Mexico neovolcanic belt that has been relocated along a transform fault. Other lines of evidence are also considered.
CLAY‐MINERAL STUDIES OF THE SUBSURFACE NIGER DELTA
Authors: Odigi M. I. 
Published: December 2007

Mineralogical studies of Tertiary subsurface sediments in the Niger Delta have shown that smectite, kaolinite, mixed‐layer illite/smectite and illite are the principal clay minerals, with subordinate quantities of chlorite. Clays from the Recent delta have similar mineralogical compositions.Sediments in the eastern Niger Delta are contributed by rivers which drain the Oban and Bamenda Massifs, and the Tertiary volcanics and Cretaceous sediments of the Benue Trough. Sediments in the central and western delta are derived by weathering of the North, Central and SW Nigerian Basement, and also from Cretaceous sediments which are drained by the Niger/Benue river systems.The clay‐mineral assemblages of the western, central and eastern Niger Delta sequences differ. These differences are thought to be related to geothermal gradients, environments of deposition, source materials, pore‐waters chemistry and basin tectonics.Clay‐mineral assemblages from nine wells in the Niger Delta are used in this study as a possible means of correlation. A relationship can be established between clay mineralogy and the occurrence of hydrocarbons in the wells investigated.
A NEW HYDROCARBON “PLAY” AREA OFFSHORE SOCOTRA ISLAND, REPUBLIC OF YEMEN
Authors: Richardson S. M. , Bott W. F. , Smith B. A. , Hollar W. D. , Bermingham P. M. 
Published: December 2007

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 be tested during 1995.
RESERVOIR POTENTIAL OF THE MAASTRICHTIAN PAB SANDSTONE IN THE EASTERN SULAIMAN FOLD‐BELT, PAKISTAN
Authors: Sultan M. , Gipson M. 
Published: December 2007

The hard, resistant, generally cliff‐forming Pab Sandstone Formation of Maastrichtian age is well exposed in parts of the eastern Sulaiman Fold‐Belt. Thin‐section, XRD and SEM studies of 66 samples from seven outcrops extending 200 km along strike were made in order to assess the reservoir quality of this formation. Petrographic studies indicated that the sandstones, classified as quartz arenites (locally subarkose), are texturally and mineralogically mature. The proportion of potassium feldspar varied from trace to 16%, and this mineral was confined to certain stratigraphic zones. Alteration of feldspars to clay minerals was common, particularly in the south of the study area. Plagioclase, heavy minerals, and lithic fragments were present in minor amounts.Diagenetic kaolinite, illite and chlorite were common, with kaolinite being the most abundant. Quartz overgrowths constitute the dominant cement. The reservoir quality of the formation largely depends on the composition of the sandstone, and its susceptibility to chemical alteration. Most of the porosity (up to 16%) results from the dissolution of feldspar grains; dissolution was restricted to the south of the study area, and the feldspars in the north show little alteration and no dissolution.Reservoir potential has also been influenced by the substantial input of silica‐rich solutions that completely destroyed the primary porosity of the sandstone. The observed porosity is mostly secondary, commonly formed by dissolution of feldspar grains, and occasionally cement/matrix.The sequence of diagenetic events is, from oldest to youngest: formation of pyrite; formation of early‐stage calcite; formation of dolomite; silica cementation; formation of clays; precipitation of late‐stage calcite; feldspar dissolution; and formation of iron oxides. The textural and mineralogical maturity, coupled with local well‐developed secondary porosity, may make the Pab Sandstone Formation a good reservoir rock.
POROSITY EVALUATION OF SEISMICALLY‐RESOLVED ZECHSTEIN CARBONATE LAYERS, LøGUMKLOSTER‐1 WELL, DENMARK
Authors: Maver K. G. 
Published: December 2007

Seismic modelling has been applied to define the porous carbonate intervals and lithologic boundaries resolved in the seismic section at the Løgumkloster‐ 1 Well, southern Jylland, Denmark, This well encountered a 14‐m thick, porous Zechstein carbonate interval (Ca‐2) with an oil show, but the well was plugged and abandoned.Band‐pass filtering and blocking of the acoustic‐impedance log in the time domain have been used to define a number of successive acoustic‐impedance models. The simplest of these, from which a synthetic seismogram correlates with the synthetic seismogram derived from the original acoustic‐impedance log, is assumed to define the maximum number of intervals resolved in the seismic section at the well location. As the well data was acquired in an area represented by a variable seismic reflection pattern, a new optimal seismic section CMP location was found, to optimise the correlation between the synthetic seismogram and the seismic section.Fifteen acoustic‐impedance intervals could be resolved in the seismic section at the Løgumkloster‐1 Well location, including the porous Ca‐2 carbonate interval. A close relationship was found between the Ca‐lb, Ca‐2 and Ca‐3 carbonate layers and lateral variations in the seismic reflection pattern, which indicates significant porosity variations.
PETROLEUM POTENTIAL OF THE FALKLAND ISLANDS OFFSHORE AREA
Authors: Richards P.C. , Gatliff R.W. , Quinn M.F. , Fannin N.G.T. 
Published: December 2007

Rocks of Precambrian, Palaeozoic and Early Mesozoic ages are present on the Falkland Islands. The islands are surrounded by extensive Mesozoic‐Cenozoic basins that developed as failed rift systems during the initial stages of Gondwana separation. Large tracts of acreage in three of these basins (the Falkland Plateau Basin, South Falkland Basin and North Falkland Basin) were opened for licensing for the first time in October, 1995.The area has undergone little exploration other than the acquisition of regional seismic data, and interpretations of stratigraphy and basin history are therefore somewhat conjectural. The basins are believed to contain Jurassic to earliest Cretaceous syn‐rift sediments. Probable marine and lacustrine source rocks, and reservoir rocks eroded from clean Palaeozoic quartzites, are predicted to occur within this syn‐rift succession. Thick argillaceous intervals probably accumulated during a post‐Valanginian thermal sag phase. This sag phase was interrupted by regional uplift, particularly during the Early Cenozoic.A variety of “play” concepts can be established within each basin, and potentially large structural targets can be defined on the reconnaissance seismic data available from the area.The region is considered to be one of the World's last true “frontier” exploration areas, where large, deep, Mesozoic failed‐rift basins remain to be drilled and explored.
RELATIONSHIPS BETWEEN SHALE CONTENT AND GRAIN‐SIZE PARAMETERS IN THE SAFANIYA SANDSTONE RESERVOIR, NE SAUDI ARABIA
Authors: Saner S. , Cagatay M. N. , Sanounah A. M. Al 
Published: December 2007

The grain‐size distribution of a sediment is controlled by the hydrodynamics of the depositional environment. There is a relationship between the petrophysical properties of a reservoir rock, such as porosity and permeability, and the grain‐size distribution. Therefore, the grain‐size distribution is important in interpreting both the depositional environment and the petrophysical properties of a sedimentary rock. Determination of the grain‐size parameters from gamma‐ray and/or other shale‐indicator well logs may be possible if the necessary correlations are established.Relationships between the shale content and the grain‐size parameters of samples from the Lower Cretaceous Safaniya Sandstone Member in NE Saudi Arabia were investigated by grain‐size analyses of 47 samples using sieving and a Microscan II particle‐size analyzer. Analysed samples were “clean” and “shaly” fine‐ to very fine‐grained sandstones. Grain‐size distribution curves revealed a finer mean, poorer sorting, finer skewness, and a leptokurtic distribution with increasing shale content. The shale content associated with the finer grain sizes promoted a reduction in porosity and permeability, which is a common occurrence in sandstones.In the studied well, a reasonable correlation between the grain‐size parameters and the shaliness log was observed. Vertical variations in the parameters for the sequence indicated two coarsening‐upwards and one fining‐upwards depositional cycles.