Blocks Of Shale Research Articles

A mathematical model for the retorting of a large block of oil shale: effect of the internal temperature gradient

A mathematical model which incorporates the intrinsic kinetics of the decomposition of kerogen and carbonate minerals and the internal as well as external heat-transfer effects has been developed. This rigorous model is compared with the uniform-temperature model. The results indicate that at a heating rate of 1 °C/min and a mass velocity of gas of 0.0179 kg m 2 s, the uniform-temperature model gives about 10% error in the extent of conversion for particles of 6 cm in radius. As the particle size increases, the error becomes greater. Also, at higher heating rates or mass velocities the error is larger for the same particle size. The new model has been applied to the results of thermogravimetric experiments published in the literature. The comparison shows that the rigorous model describes the retorting of oil shale more accurately than the shrinking-core model or the uniform-temperature model.

The preservation of the Neogene Brassington Formation of the southern Pennines and its bearing on the evolution of Upland Britain

The Brassington Formation of the southern Pennines comprises a succession of sands, gravels and clays, the youngest beds of which contain Lower Pliocene fossil plants. These strata are generally considered to have foundered into the Carboniferous Limestone through solution subsidence mechanisms. The subsidencc cavities also contain detached marginal blocks of shale, which locally contain Namurian goniatites. Examination of the shale blocks from a number of widely separated localities has revealed that all contain Namurian spore assemblages, datable in some cases as E 2 (Arnsbergian) age. The contact between the shale blocks and oldest sands of the Brassington Formation is unconformable and, characteristically, the latter are seen to rest on zones of lilac-stained weathered shale, representing a pre-subsidence land surface. Evidence is presented which indicates that the Brassington Formation strata are conformable and that the succession represents a single cycle of sedimentation. Because of this conformable relationship it is inferred that this land surface is also of Lower Pliocenc (or Upper Miocene) age. A tacheometric survey of a well-exposed solution subsidence complex at the Bees Nest Pit, Brassington, has enabled structure contour maps to be made of key horizons in the succession. Laboratory tests have been conducted which have attempted to duplicate this structure and so indicate the probable subsidence mcchanisms. Results suggest that subsidence was gradual, with block-by-block removal of the host limestone, and took place in deep, steep-sided pipe-like forms. The depth of subsidence, and hence the elevation of the land surface prior to the deposition of the Brassington Formation, has been determined by estimating the thickness of limestone and Namurian shale which, as suggested by previous research work in the southern Pennines, was once present over the sites of the present subsidence masses. Subsidence can be shown to be of the order of 150–250 m, which implies that the Lower Pliocene land surface of the southern Pennines lay at about 450m O.D. Based on the evidence of the contemporary sea level, the presence of the Lower Pleistocene deposits of s e England, and the sub-Neogene surface of the southern Pennines, a graph has been constructed which suggests broadly that Upland Britain has undergone a regular uplift since the main Alpine episode at a rate of about 1 metre in 15,250 years. In this light, the possible age of other well known planation surfaces is discussed.

Les series transgressives d'age oligo-miocene inferieur de l'Apennin meridional; consequences tectoniques et paleogeographiques

Abstract Uppermost Stampian-lower Aquitanian, upper Aquitanian (lower Burdigalian), tectonic events, shale blocks, foraminifera

Fracturing Oil Shale With Electricity

Abstract Laboratory studies to evaluate the use of electricity for fracturing various grades of Colorado oil shale were started in 1964. Breakdown voltages varied greatly from one grade of shale to another, ranging from a minimum of 300 v to a maximum of 15,000 v. With few exceptions, the shale samples were readily fractured at relatively low current levels. On the basis of encouraging results obtained in the laboratory, experiments were expanded to field tests to study electrical characteristics of oil shale when subjected to overburden pressure. These tests generally confirmed the laboratory experiments. Fracturing was accomplished at all electrode spacings used. The spacings varied from 3 to 129 ft. Based upon results obtained in these field experiments, additional fracturing tests were conducted in four shallow wells drilled in an oil shale formation. Some new permeable zones were created between wells. The induced permeability was improved by detonating two conventional nitroglycerin wellbore shots in one of the wells. Introduction Before an in situ retorting process can function, it is necessary to develop techniques to increase the permeability of the oil shale formation. Induced fracturing, the best method of increasing the effective permeability of oil-shale deposits, may be accomplished by hydraulic pressure, high explosives, high-voltage electricity or combinations of two or more of these. This article discusses the laboratory experiments and preliminary field tests being made to study high-voltage electricity as a method of fracturing oil shale. Fracturing is the first phase of the electrocarbonization process and is the phase with which this investigation is primarily concerned. Several investigators have studied the electrocarbonization process as applied in coal, petroleum and oil shale formations, but none has reported making field tests in Green River oil shale. Laboratory Experiments Preliminary Studies Samples used for the preliminary tests to evaluate electrical properties of various types of oil shale ranged in size from 2 to 175 lb and represented a broad spectrum of Colorado oil shales ranging from 1.5 to 58.6 gal of oil per ton of shale. The first tests determined the breakdown voltage required to initiate a current flow of 5 milliamp through the sample. In all cases, 1/4-in. stainless steel tubes spaced 4 in. apart were used as the electrodes. Breakdown voltages varied greatly from one sample to another, ranging from 300 to 15,000 V. Fracturing Studies Establishment of Air Communication After it was definitely established that electrical fracturing could be accomplished, other factors related to an in situ retorting process were investigated. The first of these was the establishment of air communication between two or more holes drilled at different locations in the shale block. Experiments were conducted on several shale blocks in which three holes were drilled in a line and spaced 2 in. apart, with 1/4-in. perforated steel tubes cemented into the holes. In most cases, interconnecting fractures created by the electrical current permitted substantial amounts of air to flow between all three holes. In these experiments the entire length of the steel tubes served as the electrodes; under these conditions the fractures occurred at random along the low-resistance paths taken by the electric current. Controlled Fracturing Fracturing at random is not a satisfactory solution to the problem. For an in situ retorting operation to be successful, a technique is required to create a system of horizontal fractures vertically spaced at preselected intervals. Accurate control of positioning the horizontal fractures is essential because the combustion process may require a vertical spacing between fractures of as little as 1 or 2 ft In Feb., 1965, experiments were initiated to investigate the feasibility of creating a controlled system of horizontal fractures. Electrodes used in these experiments were designed to concentrate the current at a small, well defined contact point. The first experiments were made with slabs of oil shale weighing 150 to 300 lb. Horizontal fractures were induced at preselected levels vertically spaced at 3-in. intervals (Fig. 1). Based on these results the experiments were expanded to involve oil shale slabs weighing several tons. The slab shown in Fig. 2 assayed at 55.7 gal of oil per ton. The top of the slab was first leveled off by inducing a fracture at the base of the peak. Two 1-in. diameter holes spaced 4 ft apart were drilled to a depth of 36 in. JPT P. 37ˆ

On a New Form of Blattoid from the Coal Measures of the Forest of Dean

I am indebted to Dr. A. Morley Davies, F.G.S., for the opportunity of examining and describing a blattoid forewing or tegmen collected upon the spoil-heap of the Harrow Hill Mine, Drybrook (Forest of Dean), during the course of a visit to that place by a party of students from the Imperial College of Science & Technology in 1921. The wing is a right forewing or tegmen, and lies upon a block of grey shale containing plant-remains. The tegmen is somewhat large for a blattoid, having a length of 44 mm., and a greatest width (across the anal area) of 19 mm: it is thus a little over twice as long as wide. The surface is densely chitinous and lustrous, with sunken veins, while the wing presents structures not hitherto seen, so far as I know, in any other British or European blattoid. The outer (costal) margin is moderately convex along the proximal two-thirds, and then curves more abruptly inwards over the distal third, so that the wing-apex is carried backward towards the inner margin, to which it is joined by a short curve. The inner margin is convex over the anal area, concave in the middle, and a little convex over the distal cubital area, where it passes by the short curve mentioned into the blunt apex. The double curvature of the inner margin imparts to the wing a somewhat humped appearance. The costal area is very wide basally, somewhat triangular, and terminates in an acute angle beyond the middle

Proceedings of Session 1889-90

Society's Rooms, 207 Bath Street, 10th October, 1889. Mr. Daniel M'Millan, Vice-President , in the Chair. The Chairman welcomed the Members and hoped that the Session just commenced might prove no way behind any of its predecessors in interest and value. Mr. Robert Woodburn Gillan, Indian Civil Service, The Manse, Carmunnock, was elected an Ordinary Member. Mr. John Young, F.G.S., exhibited a fine series of specimens of Polyzoa and Monticulipora, comprising over 20 species, discovered by himself this summer at Kirktonholm, East Kilbride, in Carboniferous limestone shale. He explained that most of the specimens exhibited were extracted from blocks of shale which had been partly burnt in the kilns. The shale in its natural condition is of a dark blackish grey colour, but it changes through burning to a rock of a yellowish grey, the fronds of the Polyzoa being a brownish black, and their lace-like structure contrasting more strongly with the colour of the stone than when found in unburnt shale. Mr. Joseph Sommerville, V.P. , exhibited a fine Quartz Crystal, with a Cavity containing Fluid, from the Calciferous Sandstone of New York State, U.S. Such specimens are geologically of great interest. Remarks on the subject of fluids enclosed in mineral cavities were made by Messrs. John Young, F.G.S., James Thomson, F.G.S., R. Dunlop, and other members. The Hon. Secretary (Mr. James B. Murdoch), on behalf of Mr. James Bennie, of the Geological Survey of Scotland, read a paper entitled “On Things New and Old from the Ancient Lake of Cowdenglen, This 250-word extract was created in the absence of an abstract

VIII.—On Some Small Bivalve Shells from the Karoo Formation, South Africa

Amongst the specimens sent many years ago, from South Africa, by the late Mr. Andrew Geddes Bain, to the Geological Society of London, are two small blocks of greenish-grey hard mudstone or shale, very slightly calcareons; one bed-plane in each, specimen bears upon its surface numerous valves of one or more forms of small Lamellibranchs, closely resembling the shells of the genera Cyrena and Cyclas in contour.

On some recently discovered fossiliferous beds in the Silurian rocks of the Pentland Hills

A few years ago I read a short notice before this Society on some blocks of Fossiliferous Limestone which I had discovered in the Conglomerate at Habbie’s Howe, in the Pentland Hills. This Conglomerate, considered by Professor Geikie to be of Old Red Sandstone age, obtains a considerable thickness in this locality, and is well exposed in the gorge through which the Logan Burn runs from the higher valley into the lower about half-a-mile above the Loganlee reservoir. The Conglomerate is mostly composed of rounded and lenticular pebbles and blocks of Silurian grit and shale, without any appearance of fossils; but while examining the beds I discovered several masses of limestone, which upon inspection proved to be very fossiliferous. The limestone of which these blocks are composed has a coarse granular appearance, and is largely made up of corals of the genera Halysites, Heliolites, Favosites, and Petraia. Along with fragments of Encrinites and several species of Brachiopoda, it also contains a peculiar rounded body of a grayish colour, which appeared like a pebble in the limestone blocks. These Mr D. J. Brown, who accompanied me on several occasions, and myself, considered to be an organism; and on showing one of them to Mr Charles Peach he undertook to make a section from it for microscopic examination. This he succeeded in doing in a very satisfactory manner, and submitted the section to Mr Robert Etheridge, jun., who determined it to be a coral of a very fine structure; and, in a

On the Lias Outliers at Knowle and Wootton Warwen in South Warwickshire, and on the Presence of the Lias or Rhætic Bone-bed at Copt Heath, its furthest Northern Extension hitherto recognized in that County

T he Liassic outlier at Copt Heath, near Knowle, eleven miles south-east of Birmingham, has been referred to in the ‘Geological Transactions’ by my lamented friend, the late Hugh E. Strickland, and it was first noticed by my friend Dr. Lloyd; but it does not appear that any particular account has been given either of the one near Knowle or of the others in the neighbourhood of Wootton Warwen, which are, however, of sufficient interest to deserve a more detailed report. The outlier at Knowle is of limited extent, being about a mile and a half in length and half a mile broad. It occurs in the midst of the Red Marl, by which it is surrounded on all sides. A few bands of limestone are seen cropping out on the side of the canal; but the main mass is quarried by a shaft, so that the order of succession is not very easy to be traced; and as the works did not pay, they have been again closed, though a quantity of stone was raised in 1857. Judging from the blocks of stone and shale still remaining, they seem to represent the Saurian beds; and the presence of beautifully preserved specimens of Ammonites planorbis confirms this. Some of the masses of limestone are of large size, and contain remains of Saurians, scales of Fish, Ostrea, Modiola, Cardium , and a few other shells; the black laminated shales yield, besides the A. planorbis , a small Pecten and plates of a Cidaris . It