Depositional Environment Drive as Overpressure Generation: Study Case in “Gap” Field, North West Java Basin

Author(s):  
A., C. Prasetyo

Overpressure existence represents a geological hazard; therefore, an accurate pore pressure prediction is critical for well planning and drilling procedures, etc. Overpressure is a geological phenomenon usually generated by two mechanisms, loading (disequilibrium compaction) and unloading mechanisms (diagenesis and hydrocarbon generation) and they are all geological processes. This research was conducted based on analytical and descriptive methods integrated with well data including wireline log, laboratory test and well test data. This research was conducted based on quantitative estimate of pore pressures using the Eaton Method. The stages are determining shale intervals with GR logs, calculating vertical stress/overburden stress values, determining normal compaction trends, making cross plots of sonic logs against density logs, calculating geothermal gradients, analyzing hydrocarbon maturity, and calculating sedimentation rates with burial history. The research conducted an analysis method on the distribution of clay mineral composition to determine depositional environment and its relationship to overpressure. The wells include GAP-01, GAP-02, GAP-03, and GAP-04 which has an overpressure zone range at depth 8501-10988 ft. The pressure value within the 4 wells has a range between 4358-7451 Psi. Overpressure mechanism in the GAP field is caused by non-loading mechanism (clay mineral diagenesis and hydrocarbon maturation). Overpressure distribution is controlled by its stratigraphy. Therefore, it is possible overpressure is spread quite broadly, especially in the low morphology of the “GAP” Field. This relates to the delta depositional environment with thick shale. Based on clay minerals distribution, the northern part (GAP 02 & 03) has more clay mineral content compared to the south and this can be interpreted increasingly towards sea (low energy regime) and facies turned into pro-delta. Overpressure might be found shallower in the north than the south due to higher clay mineral content present to the north.

1987 ◽  
Vol 107 ◽  
pp. 182-182
Author(s):  
Reynold Higgins

A recent discovery on the island of Aegina by Professor H. Walter (University of Salzburg) throws a new light on the origins of the so-called Aegina Treasure in the British Museum.In 1982 the Austrians were excavating the Bronze Age settlement on Cape Kolonna, to the north-west of Aegina town. Immediately to the east of the ruined Temple of Apollo, and close to the South Gate of the prehistoric Lower Town, they found an unrobbed shaft grave containing the burial of a warrior. The gravegoods (now exhibited in the splendid new Museum on the Kolonna site) included a bronze sword with a gold and ivory hilt, three bronze daggers, one with gold fittings, a bronze spear-head, arrowheads of obsidian, boar's tusks from a helmet, and fragments of a gold diadem (plate Va). The grave also contained Middle Minoan, Middle Cycladic, and Middle Helladic (Mattpainted) pottery. The pottery and the location of the grave in association with the ‘Ninth City’ combine to give a date for the burial of about 1700 BC; and the richness of the grave-goods would suggest that the dead man was a king.


2018 ◽  
Vol 36 (5) ◽  
pp. 1229-1244
Author(s):  
Xiao-Rong Qu ◽  
Yan-Ming Zhu ◽  
Wu Li ◽  
Xin Tang ◽  
Han Zhang

The Huanghua Depression is located in the north-centre of Bohai Bay Basin, which is a rift basin developed in the Mesozoic over the basement of the Huabei Platform, China. Permo-Carboniferous source rocks were formed in the Huanghua Depression, which has experienced multiple complicated tectonic alterations with inhomogeneous uplift, deformation, buried depth and magma effect. As a result, the hydrocarbon generation evolution of Permo-Carboniferous source rocks was characterized by discontinuity and grading. On the basis of a detailed study on tectonic-burial history, the paper worked on the burial history, heating history and hydrocarbon generation history of Permo-Carboniferous source rocks in the Huanghua Depression combined with apatite fission track testing and fluid inclusion analyses using the EASY% Ro numerical simulation. The results revealed that their maturity evolved in stages with multiple hydrocarbon generations. In this paper, we clarified the tectonic episode, the strength of hydrocarbon generation and the time–spatial distribution of hydrocarbon regeneration. Finally, an important conclusion was made that the hydrocarbon regeneration of Permo-Carboniferous source rocks occurred in the Late Cenozoic and the subordinate depressions were brought forward as advantage zones for the depth exploration of Permo-Carboniferous oil and gas in the middle-northern part of the Huanghua Depression, Bohai Bay Basin, China.


1954 ◽  
Vol 49 ◽  
pp. 267-291
Author(s):  
Elizabeth B. Wace

The Cyclopean Terrace Building lies to the north-west of the Lion Gate on the northern end of the Panagia Ridge and faces almost due west across the valley of the Kephissos and modern main road from Corinth to Argos. It lies just below the 200 m. contour line, and one terrace below the houses excavated in 1950–51 by Dr. Papadimitriou and Mr. Petsas to the east at the same end of the ridge. The area contains a complex of buildings, both successive and contemporary, and in view of the discovery of structures both to the south-west and, by the Greek Archaeological Service, to the north-east it is likely that this whole slope was covered by a portion of the outer town of Mycenae. This report will deal only with the structure to which the name Cyclopean Terrace Building was originally given, the so-called ‘North Megaron’, supported by the heavy main terrace wall.The excavation of this structure was begun in 1923. The main terrace wall was cleared and two L.H. IIIC burials discovered in the top of the fill in the south room. In 1950 it was decided to attempt to clear this building entirely in an endeavour to find out its date and purpose. The clearing was not, however, substantially completed until the close of the 1953 excavation season, and this report presents the available evidence for the date as determined by the pottery found beneath the building; the purpose is still a matter for study, though various tentative conclusions can be put forward.


2017 ◽  
Vol 31 (3) ◽  
pp. 393-400 ◽  
Author(s):  
Renato Ribeiro Passos ◽  
Liovando Marciano da Costa ◽  
Igor Rodrigues de Assis ◽  
Danilo Andrade Santos ◽  
Hugo Alberto Ruiz ◽  
...  

AbstractThe efficient use of water is increasingly important and proper soil management, within the specificities of each region of the country, allows achieving greater efficiency. The South and Caparaó regions of Espírito Santo, Brazil are characterized by relief of ‘hill seas’ with differences in the degree of pasture degradation due to sun exposure. The objective of this study was to evaluate the least limiting water range in Udox soil under degraded pastures with two faces of exposure to the sun and three pedoenvironments. In each pedoenvironment, namely Alegre, Celina, and Café, two areas were selected, one with exposure on the North/West face and the other on the South/East face. In each of these areas, undisturbed soil samples were collected at 0-10 cm depth to determine the least limiting water range. The exposed face of the pasture that received the highest solar incidence (North/West) presented the lowest values in least limiting water range. The least limiting water range proved to be a physical quality indicator for Udox soil under degraded pastures.


1920 ◽  
Vol 3 (2) ◽  
pp. 219-243
Author(s):  
J. Reid Moir

When visiting Mundesley, in Norfolk, in September, 1916, the present author found upon the shore, in close proximity to an exposure of clay which he now considers to be referable to the Cromer Forest Bed Series, a very finely-made and large flint flake, of human manufacture. This discovery induced him to again visit Mundesley, and during this year (1919) close upon three weeks have been spent in an examination of the stretch of cliffs and shore lying between Trimingham, to the north-west of Mundesley, and Bacton, which lies to the south-east.The author's researches have been greatly helped by the co-operation of three friends, Professor A. S. Barnes, Mr. Walter B. Nichols, and the Hon. Robert Gathorne-Hardy, who accompanied him to Mundesley, and to whom he offers his warmest thanks. He would, however, wish to make it clear that these gentlemen are in no way responsible for the statements made in this paper. For these the author is solely responsible.


Iraq ◽  
2002 ◽  
Vol 64 ◽  
pp. 135-216 ◽  
Author(s):  
J. E. Reade

The buildings on the citadel of Nimrud, ancient Kalah or Kalḫu, constitute a most impressive monument (Fig. 1; Postgate and Reade 1980), but the sporadic way in which they have been excavated leaves many questions unanswered. One puzzling area lies north and north-east of the great North-West Palace. It includes the ziggurrat, and the shrines of Ninurta, of Ištar Šarrat Nipḫi (formerly read Bēlat Māti) and of the Kidmuri (or Ištar Bēlat Kidmuri). Their interrelationships have yet to be established, and texts refer to further gods resident at Kalah. Excavations in this quarter were conducted by Layard, Rassam, Rawlinson, Loftus and Smith in the nineteenth century, and by Mallowan in the 1950s, and were resumed by staff of the Iraq Directorate-General of Antiquities in the early 1970s. This paper summarizes some of what we know or may deduce about the area, and defines some of the remaining problems; it does not include, except in passing, the relatively well-known Nabû Temple to the south. I have endeavoured to refer to all items except sherds found during British excavations in the area, but have not attempted the detailed publication which many of the objects, groups of objects, and pottery records may merit.A possible arrangement of the buildings in this area of Nimrud about 800 BC is given in Fig. 2, but it is a reconstruction from inadequate evidence. The relative dates, dimensions, locations and orientations of many excavated structures are arguable, and the plans published by different excavators cannot be fully reconciled. Major uncertainties concern the ziggurrat, the citadel-wall, the Kidmuri shrine and the area between the North-West Palace and the Ninurta shrine. There are many minor uncertainties. My reconstruction includes speculative features, while omitting some excavated walls which I regard as secondary.


1904 ◽  
Vol 1 (6) ◽  
pp. 265-272
Author(s):  
P. W. Stuart-Menteath

On the rail to Biarritz the roots of the Pyrenees first appear at Dax, and are accompanied by those ophites and thermal springs which are special features of the entire chain. Vast deposits of salt, to whose first development I contributed, have added an important industry to the resources of this ancient capital of Aquœ Tarbelliœ, where the exact harness depicted on Roman medals is still characteristic of every cart. Beneath the existing ditch of the Roman fortifications rock-salt was accidentally discovered by a boring for mineral water, and the salt is now worked at three miles to the south-east, and is indicated by springs for a distance of seven miles. The deposit is known to be about 100 feet in thickness, but is of unknown depth beneath the existing borings.Along the entire outskirts of both sides of the Pyrenees similar salt deposits abound, and they are often similarly accompanied by igneous rocks.The salt formation of Dax is distinctly limited by the valley of the Adour, which here ceases to wander among the sands of the plain, and is suddenly and sharply diverted along a tectonic depression, running towards the Pyrenees in a south-west direction. Precisely parallel to this course, in the Cretaceous and Tertiary rocks of the Pyrenees, there runs, at a dozen miles to the north-west, the most remarkable example known of a tectonic valley sunk beneath the ocean. The Gouf de Capbreton, sinking with steep sides to over 3,000 feet beneath the even bottom of the Atlantic skirt, and affording evidence of igneous rocks in its surroundings and in the irregularities of its floor, is a perfect analogue of the neighbouring tectonic portion of the Adour.


1954 ◽  
Vol 2 (16) ◽  
pp. 423-428

AbstractMorsárjökull is a small outlet glacier of Vatnajökull, Iceland. Two outlet streams from the ice cap unite at the foot of a precipitous step and carry a well-developed medial moraine; the north-west glacier stream is fed by a steep ice fall, the south-eastern one has been fed only by avalanches since 1938.The movement of the glacier was measured and showed that the alternate dark and light ogives were one year’s movement apart. Their characteristics are described and tentative suggestions concerning their mode of origin are proposed.


1913 ◽  
Vol 10 (5) ◽  
pp. 205-215 ◽  
Author(s):  
A. R. Horwood

Although the Rhætic beds are not exposed continuously along the eastern boundary of the Keuper outcrop, they have been proved at many points from the River Trent in the north on the Nottinghamshire border to Glen Parva in the south. South of this point there is so much drift, and borings within the Liassic outcrop have been so isolated or shallow, that there is a gap in our knowledge of the intervening ground between the last point and the Rugby district. The Countesthorpe boring, carried to a depth of over 600 feet, encountered Upper Keuper beneath the Drift, with no intervening Rhætics. Commencing in the north in the Gotham district the two outliers are capped above the Red Marl and Tea-green Marl with Rhætic beds, and Lower Lias Limestone (Ps. planorbe zone) above. At Ash Spinney at the south end of the southern outlier, and at the east end of Crownend Wood, Black Shales with Avicula contorta crop out; and on the west side septaria are seen. On the north-west side of the northern outlier at Cottager's Hill Protocardium phillipianum has been found in a well-section near the lane. Rhætic shales are seen in the shafts driven for gypsum works about Gotham.


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