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This paper describes a new technique for effective placement of delineationwells on the basis of the change of the uncertainty in the key global-reservesvariable. Uncertainty is summarized through the geostatistical framework. Theauthors develop a numerical and analytical methodology that is tested onsynthetic and real petroleum case studies. The implementation isstraightforward, and the results are promising. A methodology is developed toassist in delineation-well placement. Decisions for new-well locations areassisted with a quantitative measure of the expected reduction in globaluncertainty in the volume of original oil in place (OOIP). The availablerealizations are analyzed and processed to quantify the impact of wellplacement. Variograms and other required statistics are inferred from therealizations. As a result, a gridded map of impact values is produced, fromwhich locations with the highest impact are suggested for new-well locations.Numerical and analytical approaches for the impact-map calculation are proposedand compared. Pros and cons of each approach are summarized. The numericalapproach requires a large number of realizations for effective implementationof the impact map, which might not be practically achievable. On the otherhand, the analytical approach does not require many realizations and producesstable results. In most cases, only variogram models and current well locationsare needed for the analytical impact-map computation. Although computationaltime of this approach largely depends on the model size, some options aresuggested to reduce the cost. The analytical impact calculation is developedfor the OOIP model response, in which the petroleum reservoir is defined as acomplex geological architecture with multiple structural surface constraints.Several case studies, including a real-petroleum-reservoir example, demonstratethe use of the impact map for the assessment of new delineation-well locations.The developed tool is of significant help for well placement.
Duchesne, Mathieu J. (Geological Survey of Canada) | Brake, Virginia I. (Geological Survey of Canada) | Hu, Kezhen (Geological Survey of Canada) | Giroux, Bernard (INRS-ETE) | Walker, Emilie (Laval University)
Mexico are gaining increasing importance.
This paper presents a novel approach to modeling braided stream fluvial reservoirs. The approach is based on a hierarchical set of coordinate transformations involving relative stratigraphic coordinates, translations, rotations, and straightening functions. The emphasis is placed on geologically-sound geometric concepts and realistically attainable conditioning statistics including areal and vertical facies proportions. The equations for the eight-fold coordinate transformation, a new analytical channel cross section shape, and a real example with 20 wells are presented.
A characteristic feature of many fluvial reservoirs is the presence of sinuous sand-filled channels within a background of floodplain shale. Techniques for realistically modeling the spatial distribution of channels are necessary for reliable volumetrics connectivity assessment, and input to flow simulation. The approach presented here is applicable to stochastic modeling channel shapes and filling those shapes with porosity and permeability.
Modeling proceeds sequentially. Each major stratigraphic layer is modeled independently. The channel complex distribution, within a layer-specific stratigraphic coordinate system, is established first. Then, within each channel complex, the distribution of individual channels is simulated using appropriate transformed coordinate systems. This process is repeated down the hierarchy of geological units until the desired level of detail has been achieved. Finally, at the last coordinate system, petrophysical properties such as porosity and permeability are simulated with cell-based geostatistical algorithms within each facies.
This paper addresses the stochastic modeling of channel complexes and channels within a major reservoir layer. Multiple reservoir layers would be successively modeled and combined in a single reservoir model for volumetrics and flow simulation. At a higher level of iteration, multiple stochastic reservoir models could be constructed for assessing uncertainty.
An important feature of any approach to reservoir modeling is data conditioning. The data considered in this paper include lithofacies, porosity, and permeability data from wells, size and shape parameters of channel complexes, size and shape parameters of individual channels, vertical facies proportion curves, and areal facies proportion maps.
The approach presented in this paper has been inspired by the clear geometries observed at outcrops and as viewed from airplane windows in modern fluvial settings. There are similar object-based approaches documented in the literature. The approach adopted here is distinct from conventional object-based fluvial reservoir modeling in a number of ways, (1) the use of an explicit reversable hierarchy of coordinate transformations that is keyed to sound sequence stratigraphic concepts, (2) geologically-intuitive and accessible input data controlling channel sizes and shapes, (3) explicit control over vertically varying and areally varying facies proportions, (4) realistic asymmetric channel geometries, (5) realistic non-undulating channel top surfaces, and (6) integrated porosity and permeability models where the main directions of continuity conform to channel geometries.
Summary. The development of innovative exploratory drilling systems for Canada's harsh Arctic offshore areas over the past decade and future activity in these areas, including possible production concepts, are discussed. The results can be applied in other Arctic areas of the world, including offshore Alaska. This operating experience will advance drilling technology and serve as a basis for the design of Arctic offshore production and transportation systems. Unique technology has been developed and successfully used in the discovery of major accumulations of hydrocarbons. Continued technological advances are anticipated to have widespread Arctic applications in both exploratory and production operations.
Drilling has been successfully conducted in most of Canada's offshore areas despite the extremely harsh environmental conditions. During the past decade, technology has advanced very significantly particularly in the Beaufort Sea and Canadian Arctic Islands. particularly in the Beaufort Sea and Canadian Arctic Islands. Operating experience gained during the exploratory drilling phase is being used in the conceptual design of production systems. Undoubtedly, there will also be an evolution of technology during the development and production phases as the vast frontier reserves are exploited. Canada's offshore frontier areas typically have high costs and lengthy time spans between discovery and production. These factors present major engineering challenges for the design of safe, cost-effective, and timely exploratory and development systems. Confidence in the reservoir extent and predicted performance may permit large-scale development projects, while performance may permit large-scale development projects, while uncertainties may result in a phased approach where possible. The latter is attractive because earlier revenue is generated. Giant discoveries in the Beaufort Sea may not be essential to trigger development and a transportation system, because a combination of several pools may justify limited tankers or a small-diameter pipeline. Similarly, in such areas as the Grand Banks, phased pipeline. Similarly, in such areas as the Grand Banks, phased development with floating production platforms may be feasible. Artificial islands, first started in 1972, are still being constructed but with improved designs and equipment. A step forward has been the use of subsea berms on which concrete or steel segmented caissons have been placed. Integrated-type steel caissons have also been adapted for placement on subsea berms. One is one-half of a crude oil tanker and a second is a purpose-built steel caisson first used in 1984. Four drillships were converted and/or strengthened for Arctic service in the Beaufort Sea, and three have drilled since 1976. The second-generation floating vessel for the area is the Kulluk conical drilling unit, which began drilling in 1983 and has extended the operating season. In the Canadian Arctic Islands, drilling off artificially thickened ice in water depths exceeding 1,200 ft [365 ml has proceeded successfully since it began in 1973. On Canada's east coast, use of dynamically positioned vessels and iceberg towing have permitted seasonal drilling in positioned vessels and iceberg towing have permitted seasonal drilling in ice-infested waters. Production of oil from Hibernia and gas from Venture will be possible early in the next decade. Production of oil from the possible early in the next decade. Production of oil from the Beaufort Sea is also possible in the early 1990's and from the Canadian Arctic Islands in about the mid-1990's. Systems for such production will be discussed. production will be discussed. The focus will continue to be on exploratory drilling and delineation drilling for several years in most areas. Conceptual and preliminary engineering design for development will accelerate as new discoveries are made and others delineated. Wildcat exploratory drilling will also continue to satisfy exploration agreements and will tap the vast potential reserves of Canada's offshore areas.
The hydrocarbon potential of Canada's offshore frontiers has been recognized for several decades. Permits to explore for oil and natural gas were granted in several areas during the 1960's, when offshore drilling began on the east coast. Drilling in the Mackenzie delta and Canadian Arctic Islands (Fig. 1) in the 1960's was a forerunner to drilling offshore in those regions in the early 1970's. Encouraging hydrocarbon reservoirs have been discovered in all frontier areas except the west coast and Hudson Bay. The search has been primarily for oil in an effort to achieve self-sufficiency, security of supply, and economic returns. Significant reserves of nonassociated natural gas have also been discovered offshore and may be produced in conjunction with solution gas from offshore oil production and with nearby land-based gas reserves when a transportation system is available and demand and economic conditions warrant such production. Estimates of the potential recoverable oil and gas reserves for the frontier areas have recently been published by the Canadian federal government's Geological Survey of Canada (GSC) and are shown in Table 1.
Khan, Saeed U.; R J Brown and Associates (Far East) Pte Ltd, Singapore
The advances in offshore pipeline technology, in recent years, have been achieved by using innovative engineering to reduce construction risks and total capital costs. New design concepts and installation techniques namely: pipeline installation using the bottom tow method, pipe connections using the deflect-to-connect method and pipe trenching using marine plows have successfully been used in the North Sea, Canadian Arctic, South China Sea and Australian waters and which have resulted in significant cost savings in the material and installation costs.
With the spiraling hikes in the price of oil in the early seventies, the search and development of offshore oil/gas fields even in more non-traditional and remote areas with adverse environmental conditions, where equity capital and return ratios for such developments were previously considered significantly unattractive, was accelerated. The previously considered significantly unattractive, was accelerated. The requirements of high financial outlays for such offshore projects clearly dictated the necessity of cost savings in the materials and installation costs in order to make such developments economically viable. This obviously prompted concerted efforts towards the development of new design concepts, construction techniques and a so more sophisticated engineering analyses to reduce the construction risks and capital costs and also to alleviate maintenance and repair problems of such oil/gas transportation systems. The more severe requirements of pipelines long term stability in harsh environment and remote areas where maintenance and repair problems might result in higher costs than the actual installation cost put more emphasis on front-end engineering to obtain optimum solutions and cost-effective pipe installation and burial techniques. New design concepts and construction techniques have already proven their practicality and cost effectiveness especially in those areas where previously it was thought to be either too difficult or too expensive to develop.
This paper discusses the development and successful use of three such design concepts and installation and techniques for pipelines. These are:
- pipeline installations using the bottom tow method; - remote connections by the deflect-to-connect methods; - pipe trenching using the marine plows.
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I would like to begin my address by thanking the Society of Petroleum Engineers for the opportunity to speak to your Annual Conference about Canadian Natural Gas prospects and how they fit into the energy requirements of the North America!! continent over the next 20 years. It seems somehow an appropriate topic since the theme of this conference is "Energy Frontiers". We in Canada are very optimistic about our future energy potential. We are one of the few industrialized countries which has benefited materially from the increase in real energy prices over the past 10 years. There is some truth in the comment that if OPEC had not existed Canada would have had to invent it. The fact of the matter is that Canada is a country which has a very large resource base and has a very exiciting energy future if energy prices are high but we are energy paupers if energy is cheap and abundant.
BoardOur paper is concerned with the mine planning aspect of rockburst control. We did not intend to discuss destressing or increased fill modulus as means of controlling rockburst. I would like to explain a few matters not covered in the commentary, which did indeed cover most things. The previous mining method at the Star mine was a horizontal cut and fill method in which a flat backed pillar was created. The horizontal fill progressed up in a line toward the previously mined area above it, leaving the flat backed sill pillar. When this pillar is reduced below about 60 to 70 feet severe rockburst problems occur. The primary consideration in this paper, to make it immediately applicable in industry, was mainly the economics of the problem. We wished to devise a new mine design that would fit in directly with the present mining system, and hence must be a horizontal system, without affecting production, since the ore in the Star mine is marginal and any reduction in production could close the mine down. Economic considerations were dominant. The energy release rate design method involves nothing new. It is well documented in the literature, being first proposed by Cook at the 8th Symposium on Rock Mechanics. It is now used as a general design procedure in South Africa and accepted by mining companies throughout Africa. Hence we are doing nothing new in applying that design procedure to a mine here in the United States. What is new is a system we have arrived at of mining the center stopes approximately 50 ft. ahead of the two abutment stopes to get the lowest rate of energy release. This system could be fitted into existing practice at the Star mine with no change in machinery, and has now been operating for approximately 8 months and at the 7500 ft. level is now nearing completion. As our paper indicates the two center stopes are about 25-30 ft. from holing through the 7300 ft. level. At present we are trying to correlate the data that we are getting. We have installed a microseismic network which is now providing ample data. Previous records are not suitable to readily correlate with present data. However, the general feeling of personnel at the mine is that the severity of rockbursting has decreased significantly. More detailed conclusions will be possible in about a year. At present the 7500 ft. level is being finished and the same system is being implemented at the 7700 ft. level. With the microseismic system in operation it should be possible to obtain some correlation between the two levels. To put our paper in context I would like to first remark that at present there is only one commercial size oil shale mine in operation in America. This severely influences the design method since there is not a large data base from which to correlate pillar size and strength information as has been possible in the past in coal and some copper mines around the world.
INNOVATIONS IN PETROLEUM EXPLORATION IN THE HIGH ARCTIC Abstract The depletion of oil and gas reserves in Western Canada has made the rapid development of Canada's frontier areas one of prime importance. For seven years Panarctic has been operating successfully in one of these areas, the Arctic Islands, reaching above the mainland towards the North Pole. By exploring almost all the year round, even in total darkness and in tem- peratures to -60"F, the company is well on its way to discovering gas and oil in marketable quantities. In doing this Panarctic has overcome the harsh en- vironment by pioneering innovative techniques in- cluding the ability to drill from the ocean ice using a conventional land rig. Résumé En raison de l'épuisement des réserves de pétrole et de gaz de l'ouest canadien, la rapide mise en valeur des zones frontalières du Canada est devenue de première importance. La société Panarctic opère depuis sept ans avec succès, dans une de ces régions: les îles arctiques, qui s'étendent du continent au pôle Nord. En explorant durant presque toute l'année, même par obscurité totale et par des températures atteignant -51"C, la société est sur la bonne voie pour découvrir du pétrole et du gaz en quantités commercialisables. En agissant ainsi, Panarctic a dû surmonter les diffi- cultés d'un milieu hostile grâce à des innovations techniques comme la possibilité de forer à travers la banquise au moyen d'une installation de forage classique terrestre. 1.
Seven years ago far sighted oilmen foresaw the decline in reserves of oil and gas in the western Canada sedimentary basin and began serious explora- tion in three new frontier areas (Fig. i). Major multinational oil companies pioneered the exploration work in the first two areas-the Mackenzie Delta and the Beaufort Basin off Canada's northern main- land and the Continental Shelf off the east coast. Work in the third frontier area, the Sverdrup Basin in the Canadian Arctic Islands was spearheaded by Panarctic Oils Ltd, a consortium of 30 oil and mining companies and the Canadian Government. Success in the form of both gas and oil discoveries has been registered in all three areas. In its years of operation Panarctic has accumulated over 80 million gross permit acres and, to the end of 1974, two hundred and fifty million dollars had been spent on these lands with 70 wildcats and 10 delinea- tion wells being drilled. Six prolific shallow gas fields, - by CHARLES R. HETHERINGTON and H. J. STRAIN, Panarctic Oils Ltd, 703-6th Avenue S. W., Calgary, Canada one oil field and several encouraging shows of oil and gas have been discovered (Fig. 2). Proven gas reserves in the Arctic Islands are estimated at 12 trillion cubic feet, about half the threshold reserve required to permit economic marketing. Estimates, by various authorities, of undiscovered reserves in the Arctic Islands vary between 90 and 200 trillion cubi