Search Documents

By Rodolfo V. de la Cruz

The broad front concept is based on the principle that gasification can be achieved more efficiently and completely from a plane broad combustion front in contrast to other geometries obtainable with current methods of gasification. By restricting combustion to a plane broad front, the ideal condition for gasification is achieved. A plane broad combustion front can be developed in coal by initiating and propagating combustion from the walls of an oriented channel and collecting product gases from another similarly oriented channel. Flow will then be directed along the highest permeability of the coal bed, the available cross-sectional area for fluid flow is substantially increased and, more importantly, the increased flow will be uniformly distributed throughout the whole mass of coal. The success of the method is greatly dependent on how well an initial and rigorous permeability survey and associated corrective measures yield a well-characterized coal bed. To maintain uniform reaction rates, the advance of the combustion front is located with pressure- or mass flow-transducers. These sensors are then connected to servo-controlled mufflers for controlling segments of the fire front which are advancing ahead of others. Finally, the development of the concept to overcome problems of roof collapse, reactant and product gas leakages, and water invasion are briefly summarized.

Jan 1, 1976

By John P. Capp

In recent years limited markets have been developed for fly ash, the dust removed from coal-burning powerplant stacks, but most of it is still dumped in spoils areas at a cost ranging from 20 cents to $1.75 per ton. Aside from this cost, the creation of huge spoils areas can present a considerable aesthetic problem. Since the present annual fly ash output of about 20 million tons will probably reach 30 million by 1970, and because satisfactory disposal areas are becoming more limited, markets for much larger quantities of the waste are needed to keep disposal costs from becoming a significant economic factor in coal-burning powerplant operation. Current stress on air-pollution control and beautification, plus the vital need for good powerplant economy, makes it imperative, therefore, that coal producers and consumers expand markets and develop new applications for fly ash. Markets for established uses can be increased by making a greater effort to sell fly ash. New large tonnage markets for fly ash should be sought via more intensive, coordinated research. The economics of fly ash utilization underscores the vital role that must be played by research. To be competitive with other products, processes for the conversion of fly ash into marketable materials face difficulty in regard to two important economic factors--transportation cost and product utility--the other economic factors are favorable. Raw material costs of fly ash, for example, are quite attractive, and supply is no problem because there are many coal-burning powerplants in operation and many more are planned. Demand for products made from fly ash will grow if their utility is established and a good sales program is initiated. The major problems then are transporta¬tion costs and development of useful products.

Jan 1, 1966

By Fred N. Kissell

In This Chapter [Instruments available to measure methane in mines and tunnels Using a portable detector in both accessible and restricted spaces Machine-mounted monitors: placement and response time Calibration of catalytic detectors for different gases and Misinterpreting warning signs This chapter gives guidelines for methane measurement in mines and tunnels. The emphasis is on the measurement procedure and the interpretation of the measurement rather than on the instrument itself.] The failure to properly sample for methane is a major contributing factor to methane explosion risk. Sampling errors are most likely to occur at mines or tunnels where the presence of methane is not suspected or during nonroutine tasks at mines or tunnels known to have gas. More specific information on methane sampling at continuous miner sections is in Chapter 3. Chapters 4 and 5 discuss sampling at longwall sections, and Chapter 14 discusses sampling at tunnels. METHANE DETECTORS FOR MINING Many models of gas detectors are available to measure methane concentrations, as well as most of the other contaminant gases found in mines and tunnels. An example is the iTX Multi-Gas Monitor, a portable gas detector available from Industrial Scientific Corp., Oakdale, PA. This handheld instrument measures several gases simultaneously. The cost (2004) ranges from $1,300 to $2,200, depending on the number of gases measured. Similar instruments are available from other manufacturers. Most methane detectors used in mining use a catalytic heat of combustion sensor to detect methane and other combustible gases. These have been proven through many years of reliable operation. For detection of methane, proper operation of catalytic heat of combustion sensors

Jan 6, 2006

By Wen Tao Liu, Tong Tian, Fu Sheng Niu, Xiu Man Liang

In order to address the difficulty of accurate segmentation of froth images of different sizes, a method of froth image segmentation based on highlight correction and parameter adaptation is proposed. First, a machine vision system on a single-cell flotation machine is built to collect froth images. Homomorphic filtering is used to improve the uneven brightness and shadow of the images. Fuzzy c-means (FCM) clustering is then utilized to classify similar highlights that belong to the same froth. After Otsu threshold segmentation, a parameter-adaptive morphological operation is used to extract the marker points and edge bands and correct the froth edges in the original image. Finally, the modified image is filtered by morphological reconstruction, and the highlight mark is used as the local minimum point for watershed segmentation. Three sizes of froth images are segmented in comparative experiments. The results show that the proposed method is suitable for the segmentation of froth images of different sizes. The position of the extracted segmentation line is close to reality, with average over-segmentation and under-segmentation rates for froth images of 2.6% and 6.8%, respectively. The froth image segmentation performance is stronger than that of the other methods examined.

By M A. González, J A. Romero, D L. Fuentes, C J. Poblete, O Abdrashitova

"Robustness can be defined as the ability of a system to resist change without adapting its initial stable configuration. Robust design methodology, which is widely accepted in the manufacturing industry, allows the establishment of robustness and reliability metrics in scenario analysis.In the mining industry, a mine can be considered as a system with design parameters such as processing plant and mining capacities. Traditionally, a limited number of scenario iterations are performed in an attempt to determine optimal capacity values. An important strategic decision such as process plant capacity in particular is made during the very early stages of a mining study, often based on a low level of information. Lack of time and tools to run and analyse a larger number of possible scenarios for different design parameter combinations are usually the main reasons for not performing a full analysis. In addition, the uncertainty of other mining study input parameters creates more risk in decision-making.With advances in technology, it is now possible to automate the process of generating several thousands of scenarios in an affordable and timely manner. This allows performing the results analysis and assessing robustness and reliability criteria within a reasonable time frame. It is possible to generate a surface of results based on the net present value (NPV) for each scenario. This surface will reflect the efficiency level of the capture of the economic rent for each production scale. In addition, each scenario can be tested under diverse conditions of volatility of other external variables such as prices, costs or recoveries for example.This paper aims to establish a methodology that applies robustness criteria to determine the best scenario on several surfaces of value, which is then assessed with real data from a mining project. Obtained results demonstrate the advantages of using the proposed methodology in dealing with the above-mentioned multidimensional problems. It allows better decision-making on key design parameters and better control of the risks of a strategic mine plan.Citation:Poblete, C J, González, M A, Romero, J A, Fuentes, D L and Abdrashitova, O, 2016. Use of Robust Design Methodology for Production Scale Definition in Open Pit Mining, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 284–291 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By J. A. Mejia

The combination of high-resolution X-ray microtomography (HRXMT) image analysis and Lattice-Boltzmann Method (LBM) simulations has demonstrated the ability to describe real multiphase flow problems in fine coal filtration. The single component multiphase flow He-Chen-Zhang LBM model was used to simulate filtration with actual HRXMT images of pore network structures produced in filtration experiments. The analysis performed on coal, silica, and glass bead filter cakes showed that particle shape and wettability are two of the most important factors in the retention of moisture during filtration.

Feb 23, 2014

By DIFTIGIHT E. WOODBRIDGE

(Glen Summit Meeting, June, 1911,) DURING April, May, and June, 1910, I was in charge of an examination of the greater part of the Moa iron-ore area in Oriente Province, Cuba, on the north coast, near the east end of the island. My instructions, on arrival at the properties, were to check former estimates of tonnages and grades, and to re-examine the ore comprised in claims covering 44,727 acres. This work included .the running of lines dividing the properties into co-ordinate planes, the boring of many thousand feet of holes spaced at the intersections of these co-ordinates, the taking of samples of the ore penetrated, the analysis of these samples for their various constituent minerals, and the determination of the results as to tonnages, depths, and grades, both for individual properties and for the entire group. Each section of every one of the thousand holes drilled was to be compensated for depth and grade with every other, a series of simple arithmetical calculations of no slight magnitude, the mere mechanical labor of which consumed much time, but finally resulted in giving a complete average of all the essential facts for the entire area of 18,000 hectares. Had it not been for the more than willing, active, and able co-operation of the officers of the Spanish-American Iron Co., from Charles F. Rand, President, and Jennings S. Cox, General Manager, down to the most humble water-carrier, the work would have consumed far more time than it did. Papers prepared by others, and to which my present paper may be considered an addendum, elucidate, more fully than I could hope to do, the origin and geological character of these ores. I will confine myself to the situation, method and expense of exploration, and to probable courses of development and mining, with some attention to the cost of the ore delivered in the United States.

Mar 1, 1911

By Jamal Rostami, Mark Board, Clayr Alexander, Muthu Vinayak Thyagarajan

In the past several decades, many major equipment manufacturers have ventured into developing new technology for underground hard rock excavation. This includes variety of configurations for full and partial face mobile excavation units. Mining industry prefers machines that can excavate noncircular, flat invert profiles and be able to make tight turns in hard rock. The need to use disc cutters for cutting hard rock has impeded the development of such machines due to the need for gripper system or large mass of a machine to support the force requirements of the disc cutters. Most of the prior attempts have been partially successful and the operations have faced some practical limits and challenges. Among the units that have been successfully used, one can name mobile miner, which was used for rock excavation in some projects. A redesigned mobile miner, called the “Remote Vein Miner,” or RVM, has been developed by Epiroc for underground hard rock mining in Hecla’s Lucky Friday Mine. This equipment potentially opens numerous opportunities for innovation in civil tunneling projects, where the operational flexibility and accessibility of a TBM’s limited tunnel path, design of the profile, and cost are limiting factors. This paper explores the application of the RVM in tunneling projects, its advantages and possible areas of innovation in tunnel planning and design.

Jun 13, 2021

By VIVEK KASHYAP, Evody Tshijik Karumb, PATRICK TAYLOR

The partial reduction of zinc ferrite to zinc oxide and iron (II, III) oxide can enhance the leaching rate of zinc. Zinc ferrite has often been found as a major component of zinc residues and electric arc furnace dust. The Waelz process is an existing process for zinc ferrite processing, which requires a temperature of more than about 1200 °C to produce Waelz oxide containing ZnO. Since zinc residues have been deemed as a potential way for the extraction of zinc and other critical metals, it is important to analyze the reaction kinetics in the temperature range of interest. This manuscript discusses the chemical kinetics of zinc ferrite reduction by hydrogen gas. Several researchers studied the reduction of zinc ferrite with CO; however, unlike CO, the use of H2 gas as a reductant allows partial reduction of zinc ferrite even at low-temperature range (400–600 °C). Thermogravimetric analyses (TGA) experiments were performed in the temperature range of 300–700 °C with 10% and 30% H2, and the data obtained was analyzed using the isoconversional method of kinetic analyses. The standard models used for isoconversional kinetic analysis were chosen from literature and experimental data were fitted to determine the controlling mechanism and calculation of kinetic parameters of reduction of zinc ferrite. The rate of reaction was found to be increasing with an increase in temperature and partial pressure of H2 gas. The reaction could be divided into three stages, where reaction interface contraction was found to be the controlling mechanism at the initial stage of reaction. As the reaction proceeds, product layer thickness increases, and thus, diffusion was found to be the controlling mechanism. Roasting products obtained from TGA experiments were also characterized using a scanning electron microscope (SEM) to verify critical morphological details.

Jul 26, 2022

By K. C. Sole, M. E. Mitshiabo

Although surfactants have proven to increase metal extraction by improving solution flow in porous media, these reagents have not been widely adopted in heap leaching operations because of potential incompatibilities with downstream processes that are subject to surface properties. The BASF leaching aid, LixTRA 118, was previously found to have no significant effect on post-leach operations. This study evaluated its performance in ores of different particle size distributions and the impact on acid consumption and metal recovery. Column leach studies, carried out on a copper oxide ore and mixed oxide–sulfide ore, showed that the effect of LixTRA 118 was more pronounced in ores with wider particle size distributions than in those with more uniformly sized particles. Solution percolation rates increased by up to 18% in the presence of leaching aid, and increased copper recovery and acid consumption. Improved wetting facilitated the kinetics of acid diffusion at macroand micropore level. There was no significant effect on iron recovery

Jan 1, 2023

By Selvaganesh Selvaraju, Deepak Raj, Sandun N. Wimalasena

One of the world leading oil majors is carrying out a multi-billion-dollar expansion of its integrated manufacturing complex in Jurong Island, Singapore, the global oil trading and refining hub. Soil conditions at the site comprise 10-20m thick reclaimed sand, below which is 3-5m of soft marine clay underlain by stiff soils of the Jurong Formation. The conventional foundation solution would adopt driven precast concrete spun piles; however, precast spun piles have a high embodied carbon from the usage of steel and cement. In order to reduce the carbon footprint, an alternative solution comprising deep vibro techniques was developed. The EFFC-DFI carbon calculator was used to demonstrate the expected scope 1, 2 and 3 carbon emissions for both driven pile and vibro techniques. By using in-house, state-of-the-art fuel-efficient machines, alongside the innovative design concept and usage of natural materials such as sand and stones, actual CO2e emissions were reduced from a potential 21,000 tonnes, with the spun pile’s solution, to only 1,900 tonnes. The saved 20,100 tCO2e is equivalent to an average car driving 2,000x around the Earth’s equator. The paper discusses the application of soil improvement as a more sustainable, lower carbon alternative to conventional piled solutions.

May 1, 2022

By V. S. Tadsen

Today, man is able to probe space because of technological advancements including the ability to control certain combustion reactions very precisely. The recent adjustment of the attitude of Skylab by radio command from earth is an excellent example of such control. It is strange, and indeed unfortunate, that very little is known about the mechanism of combustion of pulverized coal, the primary fuel for rotary kilns. The selection of a coal for direct pulverized firing of a rotary lime kiln may be determined by trial and error, persistence of sales personnel, proximate analyses, grindability, or apparent BTU cost. Occasionally, the only question asked is, "How much lime will it make?" To study the behavior of a particle of coal in the combustion stream of a rotary kiln is most difficult. We must, therefore, discuss the general mechanism of combustion of pulverized coal, and relate this mechanism to the selection of a proper coal for a rotary kiln. The classic three T's -time, temperature, turbulence -must be enlarged upon for a better understanding of the problem. Pulverized coal occupies only 0.01 per cent of the volume of air required for its combustion. This mixture behaves like a gas and the general laws governing the movement of solid particles in gasses are in effect. The differential velocity between air and coal particles depends on forced and natural convection, diffusion, and the length of time each particle is in the combustion space. As a particle of coal absorbs heat from its surroundings, it begins to give off volatiles". These gasses ignite as their kindling temperature is reached, and burn readily because of the excess oxygen immediately available. Combustion proceeds at this stage by the outward diffusion of gas from the coal particle into the surrounding oxygen-rich envelope. We could say combustion at this stage represents a small coal particle surrounded by an envelope of volatiles burning at their point of contact with sufficient oxygen. This release or expulsion of gasses from the coal may result in exfoliation or disintegration of the coal particle. If this occurs, and it is desirable that it should, it will accelerate the final stages of combustion. The escape of volatile material from the particle of coal and its subsequent combustion will cause increased turbulence around that individual particle. Ignition is maintained by radiation from gasses and solids in the combustion system, and most importantly, re-radiation from the kiln refractories and the process load.

Jan 1, 1978

By M. L. Cao

In this study, a montmorillonite organo-intercalation compound (MOIC) was synthesized by using a Na-modified bentonite (NaB) as a matrix and hexadecyltrimethylammonium (HDTMA) bromide as an intercalating reagent under microwave irradiation. The synthesized products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), organic carbon content measurement, and adsorption density determination. The results show that, at 10% suspension concentration and 10 minutes irradiation in a 130-W microwave oven, the basal spacing d(001) of the synthesized MOIC increases to 2.209 nm from the original 1.218 nm of NaB. The MOIC has much higher adsorptive densities to nitrobenzene and aniline from aqueous solution than the NaB. The adsorption isotherm of nitrobenzene on the MOIC is linear, and the adsorption is mainly the result of nitrobenzene?s preferred partition in MOIC over aqueous solution due to MOIC?s hydrophobicity. The adsorption isotherm of aniline on MOIC follows the Freundlich equation and the increased adsorption is not only the result of aniline?s preferred partition in MOIC over aqueous solution but also that of the MOIC?s surface adsorptions.

Jan 1, 2014

By Cathy Aimone-Martin, Frank Achuff

The New Mexico Department of Transportation (NMDOT) and the Federal Highway Administration (FHWA) have let a contract to Sierra Blanca Constructors for a design / build contract along 38 miles US 70 in Lincoln County, New Mexico. The project will improve safety of travel along the corridor and facilitate the adopted economic development goals of the state. Proposed improvements include widening the existing highway from two lanes to four lanes, providing left turn lane options at selected locations, improving access for businesses and residences, aesthetically enhancing retaining walls, improving storm drainage and replacing the existing pavement with a 30 year mechanistic imperialistic perpetual pavement design. The US 70 Hondo Valley highway project is situated in a narrow valley with steep limestone walls, passes along a Scenic Byway and numerous historic ranching communities with structures that date back three centuries. The scope of work included requirements to monitor and mitigate blasting, noise, and vibrations. The contract was very presumptive with regard to blasting design and procedures. These included visual impact mitigation to treat and stabilize slope cuts, the Migratory Bird Treaty Act protecting roosting and nesting birds from airblast, and the protection of historic and cultural features such as acequias, wells, and structures. Public involvement affecting the rock blasting design has come from citizen task forces and committees concerned with highwall aesthetics and preserving the scenic byway and cultural resources. Constraints placed on the blasting program from agencies and the communities are often at odds. For instance, blasting must produce stable yet natural-looking walls to preserve aesthetics. Restrictions have been placed on pre-splitting and smooth-wall blasting yet safe slope are of the highest priority. This paper presents details of the design/build process undertaken by the contractors to conduct blast rock in an environmentally sensitive region. Blast designs consistent with good construction practices and used to comply with the many federal and state highway stipulations are described.

Jan 1, 2004

By A Halim

The European Union (EU) have recently issued new Threshold Limit Value-Time Weighted Average (TLV-TWA) for diesel exhaust contaminants, which are CO, NO2 and DPM. The new limits for CO and NO2 were issued in 2017 whilst the one for DPM was issued in 2019. However, in order to allow EU mines to formulate strategies to comply with these new limits, the EU granted a transition period in which mines could use the old limits until the new limits are enforced. The new limit for CO and NO2 will be enforced from 21 August 2023 whilst the one for DPM will be enforced from 21 February 2026. The new limit for NO2 and DPM is very low, 0.5 ppm for NO2 and 0.05 mg/m3 of Elemental Carbon (EC) for DPM. Combination of these two limits would be the lowest among all mining jurisdictions worldwide. It poses a huge compliance challenge to EU mines if they keep using diesel machines. Therefore, a study and a field trial were carried out by the author in 2019–2021 to investigate whether replacing diesel machines with Battery Electric Vehicles (BEVs) would be the best answer to this challenge. This paper outlines results of this study and field trial.

Oct 12, 2022

By Mark Liskowich

When is it the proper time to initiate engagement with various stakeholders, including Indigenous communities? This paper will demonstrate what stage of a project’s evolution is the appropriate time to initiate a stakeholder engagement plan. It will look at aspects to consider when identifying the communities to involve. It will describe the contents of a Stakeholder Engagement Management Plan as well and touch on how tried and true options analyses, such as a Multiple Accounts Analysis can be used to inform the results of the engagement, guide the development of your project and clearly document the engagement process. It will illustrate the benefits of initiating engagement at the appropriate point in your project’s schedule, and the limitations of doing so too early and at later stages of the project engineering. The benefits of this approach can be realized within any legislative Jurisdiction including the Canadian Environmental Assessment Act 2012 and Canada’s new Impact Assessment Act.

Jan 1, 2020

By David H. Dahlem

Uranium is a very mobile element geochemically and is widely dispersed in the lithosphere and hydrosphere. Under oxidizing conditions, it is particularly widespread and appears in all parts of the surface hydrologic system. As a result, this system is a leading candidate in uranium-resource assessments as a new base from which total resources might be estimated. No other sampling system provides the large volume geochemical capture as the continental hydrosphere and is as pervasive and non-selective regardless of rock type. However, the water system as a uranium metal sampler is not without drawbacks as the development of a National sampling program based on it has shown, In spring 1973, the National Uranium Resource Evaluation (NURE) was announced by the U. S. Atomic Energy Commission (AEC). The program was conceived to provide an evaluation of the domestic uranium resources and to identify areas favorable for uranium exploration. The specific NURE objectives are as follows (Bowyer, 1974): 1. To provide a preliminary evaluation of domestic resources and favorable exploration areas by early 1976, based on existing data. 2. To conduct a comprehensive evaluation of domestic resources and favorable areas by 1980, based on advanced state-of-the-art information. 3. To conduct an R&D program into new and improved procedures, equipment, and technology for uranium exploration and assessment. 4. To disseminate information on new exploration concepts and technology.

Jan 1, 1976

By I. Blayda

The purpose of this work is to study and make comparative analysis of germanium extraction and related valuable components of the sublimates from the burning of domestic power coals (product 1) and germanium sulfide materials, which are a waste of lead-zinc production (product 2), by traditional chemical methods (distillation of germanium in the form of tetrachloride from raw and preliminary burning source) and by microbial bioleaching of sulfur-oxidizing bacteria. The dependence of the germanium extraction by chemical methods from phase composition of the initial raw materials was installed. The germanium tetrachloride extraction from products 1 and 2 were 78.50 and 19.52%, respectively. Such difference in indexes on extraction, is caused by germanium confinement as concomitant trace component to the basic phases to carriers. The share of acid-non-soluble compounds (tetragonal modification GeO2 and silikogermanaties) in the product 1 account for 21.5 % of germanium. Ratio between acid-soluble and acid-not -soluble germanium forms are 19.52 and 80.48 %, respectively, in the product 2. Our experiments have shown, that implementation of restorative firing (with addition of 30-40 % carbon at 1150 0?) of sulfide product 2 considerably impacted on the extraction of germanium tetrachloride (91.76 %) in comparison with its low enough extraction at straight distillation of hydrochloric acid (19.52 %). The results are confirmed by a set of physical methods. The results of processing the same so-called hard phase?s material (product 2) with the help of microorganisms are presented. It Has been established, that selected strains of bacteria are capable of extracting from initial raw materials not only macro components (iron, zinc, lead, manganese, aluminum, nickel), but also micro impurity of rare metals (gallium, germanium, zirconium). It is important that these metals were not extracted by traditional chemical methods (with application of aggressive conditions and heats) independently of the phase composition of the source. Almost complete extractions of germanium in solution using sulfur-oxidizing bacteria take place in the first day of the process independently of the phase composition of the source and the type strain. The results have practical significance and can be the basis for developing a unified biotechnological method of technogenic waste processing with a purpose of their sterilization and detoxification with simultaneous obtaining concentrates of valuable metals. Keywords: germanium, extraction, sublimates, bioleaching, sulfur-oxidizing bacteria.

Sep 1, 2012

By B. Salt, R. Sullivan, E. Roos, M. de Vries, K. McKenna, L. R. Nelson, M. J. N. Uys, P. Jacobs, E. Munnik, P. Lewarne

A review is presented of the furnace cooling system design and operating developments since the initial furnace start up in January 2001 of the Chambishi DC-arc furnace to produce ferrocobalt alloy. The furnace operating conditions present a number of challenges to the furnace designers and operators in particular to provide a sustainable lining that can withstand the highly corrosive siliceous slag (roughly 50% SiO2). This is exacerbated by the dual requirement to operate this slag in a relatively highly superheated state (?T ? 400°C when tapped at 1550°C) to ensure that the ferroalloy can be tapped (estimated 1370°C alloy liquidus temperature) prior to atomisation. The core design challenge occurs at the alloy-slag interface, where a single refractory type cannot simultaneously meet the dual requirement of both adequate alloy and slag corrosion compatibility. Progression by the fourth furnace campaign to involve a retrofit of the bath sidewall to Hatch high-intensity, water-cooled, copper Waffle coolers and tapblocks is described. This involves operation of the entire slag bath, the slag-alloy interface and a portion of the alloy within a more chemically compatible refractory/slag (and possibly at times even an alloy) freeze-lining. Due to the high furnace power density employed (up to 500 kW/m2 hearth area) coupled with the large slag superheat needed, the resulting imposed peak bath sidewall heat fluxes are substantial, especially in the alloy (typically averaging 170 kW/m2), and on occasion have exceeded 1000 kW/m2. The performance of the Hatch Copper Waffle coolers under such aggressive process pyrometallurgical conditions is described. Aspects of the design and especially operating strategies to effect sustained production at up to 38 MW power input are also discussed.

Jan 1, 2004

By Nathan Deisman

Coupled reservoir geomechanical simulations have become a key component of caprock integrity assessments for SAGD operations. This work demonstrates the differences of stress evolution when considering coupled versus uncoupled reservoir simulation. Coupled simulation involves the use of a reservoir and a geomechanical simulator with feedback to each simulator to update reservoir or geomechanical variable (permeability, porosity, relative permeability, pressure, temperature, saturations). Uncoupled simulation only passes the pressure and temperature to the geomechanical simulation with no reservoir simulator updating. Therefore, it is possible to complete uncoupled simulations exclusively with no knowledge of geomechanical flow property evolution. However, it is important to understand the differences between the stress evolution in each model for caprock integrity analysis. A single geological model was selected and parametric analysis was completed while varying the geomechanical the production injection pressures (1600 kPa, 1900 kPa, 2200 kPa) for a reservoir with an initial pressure at the injector of 1300 kPa. The results of the six uncoupled and coupled models are compared through the changes in mean stress, shear stress, and strength with focus on geomechanical assessment of caprock integrity.

Jun 1, 2012