Innovative Concept of a Drilling and/or Production Platform for Operating in Arctic and Deep Water

A concept of an innovative floating platform using a conical structure was originally developed for operation in arctic region. It is called as MCAD (MonoCone Arctic Drilling Platform). The conical structure is used to reduce ice-loading as it facilitates ice to break in flexure while riding the slope of the conical surface. For supporting the weight of the platform, equipment, and ballast, a base structure with sufficient buoyancy is added at the base of conical structure. To ensure the platform with adequate stability, a heavy (solid) ballasting system that can be lowered to adjust the vertical center of gravity of the platform is incorporated in the system. The conceptual platform configuration has been analyzed for a large payload of more than 25,000 ST operating in approximately 125 feet of water depth. In the winter season, the platform is subjected to more than 12,000 ST of ice load. For warmer season the platform has been designed to survive a 45 feet significant wave height with 80 knots wind, and a very strong current of 6 knots. To withstand such magnitude of ice forces, mooring system using 32 lines was designed. For lower ice loads in a milder environment, the number of mooring lines can be reduced considerably. For operating in the warmer season, the platform was analyzed for design environments of operating and survival conditions. The motion responses in these conditions were found to be excellent in comparison to other deepwater concepts in use. With the promising motion response results of the conceptual platform with such a high payload, the concept is expected to provide operating company an alternative for deepwater application as well. Since the concept has been developed for a very large payload, the excess payload may be utilized as storages of produced oil. Mooring system for operating in deep water has been developed, and has been compared with that of the system for arctic condition. This paper describes the concept identifying the salient features. The effects of various features on the design and platform performance are also described. The ballast system with its lowering system makes this concept attractive for easy installation without the assistance of a large derrick vessel, a significant reduction of installation time is also expected. Results of stability, motion and mooring analyses is presented in the paper as well. Preliminary structural analyses were carried out to confirm the viability of the concept in operational, installation and survival conditions.

II.—Cataclysmic Theories of Geological Climate

The most important geological problem, and the one of all others which at present excites the greatest attention, is the cause of those extraordinary changes of climate which have taken place during past ages. How are we to account for the cold and Arctic condition of things which prevailed in temperate regions during what is called the Glacial Epoch, or for the warm and temperate climate enjoyed by the Arctic regions, probably up to the Pole, during part of the Miocene and other periods? Theories of the cause of those changes, of the most diverse and opposite character, have been keenly advocated, and one important result of the discussions which have recently taken place is the narrowing of the field of inquiry and the bringing of the question within proper limits.

IV.—On Changes of Climate during the Glacial Epoch

If one were asked to put into a few words the general results which have been arrived at from a study of the Glacial deposits, he would probably say that these deposits gave evidence of a severe Arctic condition of things having obtained in this country,—that the gradual approach of this Arctic climate caused the disappearance from our area of the fauna and flora which had previously characterized it,—that during the continuance of the cold in Britain several speciesof mammalia appear to have died out in the more southern regions of Europe, whither they had migrated,—and that it was not until after our climate had become greatly ameliorated that these islands were visited by what are termed the “Post-glacial mammalia,” several species of which, however, had been denizens. of Britain and northern Europe inPre-glacial times. In short, our island, throughout the Glacial period proper, is commonly supposed to have remained a barren waste of snow and ice. But the evidence which has been accumulating during recent years will compel us, I believe, to modify materially these general inferences. So far from the Glacial epoch having been one long continuous age of ice, it would appear to have been broken up by many intervening periods of less Arctic, and even temperate conditions, during whichthe snow and ice disappeared from our low grounds, and the glaciers shrunk back into our mountain valleys. I speak, of course, of that portion of the Glacial epoch which was antecedent to the general submergence, and is represented by the Till or Boulder-clay of Scotland. la this short paper I propose to give an outline of the facts upon which these conclusions are based. But before doing so it may be well to point out the order of succession of the Scottish drift deposits, which is now no longer a matter of dispute. Beginning with the lower beds, we have the following sequence

Projected Exploration of Iceland by the Alpine Club

We are glad to find tbis interesting and little-known country is likely to be visited by some of the members of this enterprising club. The address recently delivered by the Vice-President, Mr. William Longman, now lies before us, illustrated by a neatly-executed map of the wild volcanic island he seeks to bring, in a special manner, before scientific notice. It is quite surprising to think that a country so rich in the physical phenomena of moving glaciers and active volcanos has “never been explored or even visited” by any traveller who has made a study of such great causes of surface-aspect. Certain work has, however, been done, and what records of it we have been able to meet with are appended to this article. Most of them are books available for study, and for this special work perusal of them will be useful, as no doubt a goodly company of physical geologists will answer Mr. Longman's call; for existing glacial conditions in Iceland are more likely to aid them in learning the operations of the post-pliocene glacial eras, which in Britain have left such abundant records of their existence.No one who has read the last “Edinburgh Paper,” by Mr. Robert Chambers, “Ice and Water,” can fail to see how greatly our comprehension of the recent arctic condition of the British Isles will be aided by examination of that icy fringe of the northern zone, which has of late so materially influenced our climate, as if we were again menaced with a southerly extension of polar ice.