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By P. C. Parsons, G. C. Milligan

"IN FIELD WORK in the Cape Breton Highlands, which are heavily covered with vegetation, it is necessary to run traverses along the valleys of small brooks. We encountered difficulty in closing such traverses, and the following technique was developed to solve this problem. It has been tested in the field for four seasons by several people, and found to be simple, efficient and more accurate than any other compass-and-pace system of which we are aware. So far as we can find, the technique has not been described previously. It may be of use to others.The Cape Breton Highlands of Nova Scotia consist of hills of old intrusive and metamorphosed sedimentary rocks protruding up to 1,000 feet above the general level of the younger sediments which underlie the valleys. The flat hill-tops are the remnants of a plateau; drainage off the edge of this plateau has produced many small steep brooks. They occupy valleys which are up to 800 feet deep, and V-shaped in cross section, with steep sides covered by mixed conifers and hardwoods. The stream at the bottom is rarely more than a few feet wide, with a negligible meander belt, but with many bends, rapids and falls. Visibility along the stream, in consequence, is rarely more than a few hundred feet, and in many places much less.It was found impractical to map the streams by the method of meander lines, as described in many standard surveying texts and hand-books. The limited visibility, and the numerous bends of the brooks, necessitated many corners. Every corner introduces errors. To 'close' a survey with 40 or 50 such corners proved either very time-consuming or impossible. In most cases, however, the general direction of a valley may be obtained from an aerial photograph, or by direct observation, and this became the basis of the method adopted."

Jan 1, 1971

By K. Ihara, R. Akiyoshi, Y. Takaki, S. Kang, H. Shishido

"Tensile tests and scanning electron microscopy-electron backscattered diffraction (SEM-EBSD) analysis were performed in an Al-Mg-Si alloy to clarify the effect of annealing and cold-rolling reduction on the texture formation. The hot-rolled specimens were cold-rolled with the reduction of 58-75%(CR1), followed by annealing at 773 K for 5 min(IA). The secondary cold-rolling(CR2)for the IA specimens with the reduction of 33–66%, followed by the solution heat treatment(ST), were performed. Focusing on the CR1 and CR2 specimens, the average r-values increased with higher primary and lower secondary cold-rolling reduction, respectively. This was considered to be due to the increase of r-values measured in the direction of 45 degree with respect to rolling direction, caused by the formation of the ß-fiber components (Brass {011}<211>, Copper {112}<111> and S {123}<634>) with high density. Based on the texture analysis of annealed specimens it was suggested that the high density of the ß-fiber components after IA and the small amount of stored strain energy of CR2 introduced by the lower cold-rolling reduction remained the ?-fiber components even after solution treatment.INTRODUCTION Al-Mg-Si alloys have been applied to automobile body applications, due to their excellent paint-bake hardening (age-hardening) and corrosion resistance compared to other aluminum alloy. On the other hand, the mechanical properties and deep drawability of Al-Mg-Si alloys are inferior to those of steels. Thus, it is important to improve the mechanical properties and deep drawability in order to expand the application components. One of the best methods to improve the deep drawability is to increase the Lankford coefficient (r-value). Previous studies reported that the increase of the average r-value ( ) improves the deep drawability. The relationship between the r-value and texture of the alloy is also well known. Inoue et al. reported that the ß-fiber components, such as Brass ({011}<211>), Copper ({112}<111>) and S ({123}<634>), increase the r-value measured in the direction of 45o with respect to the rolling direction. r"

Jan 1, 2018

By Marc Piard

In a cool mine, tapping high-pressure lines through reducing valves lowers the temperature beyond remedy. It is the writer&apos;s suggestion that, for low-pressure work, law-pressure air ,should be generated in a compressor installed underground adjacent to the work, and that the jacket-water of the compressor should be utilised for re-heating purposes. Such a system of compressed air distribution, designed especially for service in cool mines, is described in the following notes. The suggested system includes a three-wire pole line from the sub-station to the opening nearest to the working face, with a cable connection extending to the latter from the openings; an electrical centrifugal unit; a reservoir excavated in the ground; and a distribution line, re-heated by jacket-water. As regards the reservoir, it may be pointed out that in many mines there are blind or abandoned tunnels that could be used for the purpose. The centrifugal type of compressed air machine is a comparatively new departure, and it was formerly considered that such a machine, operating at less than 1,000 kilowatts per unit, would be commercially impracticable. At the present time, however, these machines are being built in Europe for as little as 400 kilowatts per unit, and as much as 110 lb. per sq. inch pressure. One advantage which these centrifugal machines have over other types is that they may be driven by plain induction motors, without the help of special starters-a consideration of the first importance where the electrical regulations are severe.

Jan 1, 1926

By R. C. Bryce, G. S. Martin

"Aur Resources Inc. is the operator of the Louvicourt Mine located 40 km east of Val d&apos;Or. Quebec. Les Entreprises Minieres Redpath Limitée a member of the 1.S. Redpath Group of companies was contracted to construct two vertical mine shaft collars in deep overburden.During the spring of1991 two vertical shaft collars were established in wet, running sand that was in excess of20 m deep. This paper will illustrate the engineering and construction techniques used in establishing these collars and the methods used to overcome the various obstacles that occurred during construction.IntroductionThe Louvicourt copper/zinc/gold/silver deposit is located 40 km east of Val d&apos;Or, Quebec, is adjacent to the former Louvern Mine which operated at depths of 40 m to 850 m below surface (Fig. 1). This deposit was discovered in mid-1989 as the result of systematic exploration and diamond drilling based on a geological model. The Louvicourt project is operated by Aur Resources Inc.The property is being developed to produce 4000 tid with an anticipated life of just over 17 years. Mill start up is scheduled for July 1. 1994, commercial production October I, 1994, and full production by late 1995. The current production plan provides for 24 040 (XX) t averaging 3.89% copper, 1.95070 zinc, 0.039 oz gold per tonne and 0.99 oz silver per tonne, to be mined."

Jan 1, 1994

By Victor F. Hollister

Although none of the deposits discovered to date are of commercial interest, significant Frasch or sedimentary sulphur deposits occur in Nova Scotia in Upper Mississippian Windsor Group evaporites. The evaporite sequence contains anyhdrite and is overlain by impervious shales. It also is •mderlain by locally petrolijerous formations that are potential hydrocarbon sources for reaction with anhydrite to produce sulphur. As well, stratigraphic and structural traps are known to exist in the Mississippian beds. Thus, all requisites for sedimentary sulphur genesis are present. Available hydrocarbon sources are numerous but small; resultant sulphur deposits therefore are probably also small. Evidence suggests, however, that sulphur deposition is not yet complete.

Jan 1, 1984

By George Kellock

In presenting this paper for discussion at the Western Annual Meeting to be held in Edmonton, it is with the idea of creating a full and general discussion by the mining men in the Province as to the best way to eliminate, or at least hold down to a minimum, the dangerous coal-dust which is made in mining pitching seams in our Alberta mines by the chute method. Also, an alternative method is outlined, whereby the percentage of lump-coal mined can be increased, and the mining costs reduced-although the paper does not go into any detailed consideration of costs. The general trend of mining practice and lay-outs is at present towards mechanization, and the results being accomplished by the substitution of machines for manual labour are fully justifying the changes. In the technical mining journals, there are published from time to time papers dealing with a variety of methods of mining, which are descriptions of actual operations, and a great deal of interesting and valuable data is given as to the comparative values of the different methods, insofar as the percentage of grades of coal produced, the cost of production, etc., are concerned; but the mechanical methods described in these papers are nearly always suitable only for flat seams, or seams with a very low inclination.

Jan 1, 1929

By C. H. Hopper, D. R. Derry, H. S. McGowan

"The property of Matachewan Consolidated Mines is in the Matachewan area on the west side of Montreal river. It lies in the western extension of the Kirkland Lake sedimentary belt. The first discovery of gold on the property was made by S. Otisse, in 1916. The property was taken over by Ventures, Limited, in 1933 and production commenced in late 1934. To date (December 31st, 1947) it has amounted to 2,308,800 tons, from which gold and silver to the value of $9,567,600 has been recovered. The mill is currently treating 650 tons of ore a day.GENERAL GEOLOGYThe deposits lie close to the south contact of a belt of sediments striking in a general east-west direction. The sediments, presumed to be of Timiskaming age, consist of light buff arkose and greywacke, containing small pebbles. The Keewatin volcanic rocks to the south are andesites or basalts with cuff and agglomerate bands developed especially near the contact with the sediments. The lavas and sediments are overlain by relatively flat-lying sediments of the Cobalt series to the south and west of the mine, but these later sediments are not involved in the mineralization under discussion. The Keewatin lavas and Timiskaming sediments are intruded by dykes and lenses of red syenite porphyry that have approximately the same strike and dip as the invaded rocks. Later diabase dykes, apparently post-ore, run in a north-south direction and cut all rocks except the Cobalt series.OREBODIESThe gold-bearing mineralization forms bodies of two different types: (1) Within the volcanic rocks irregular orebodies with limited vertical extent. These consist of a series of flat-dipping quartz stringers and adjacent lavas and /or cuffs fractured, bleached, and mineralized with pyrite and gold. They are higher grade than the second type (average about 0.16 oz. gold a ton) and formed the main source of ore for the first 5 years of production. They are described in more detail than can be given here in an article by C. H. Hopper (4). More recent work on deeper levels has failed so far to find orebodies of comparable grade, though low-grade mineralization of a similar type does occur on the projected rake of the main group of the 'basalt type' of orebodies."

Jan 1, 1954

By Hans Lundberg

An electric survey from a &apos;plane flown over the ground is much faster and cheaper than an electric survey carried out on the ground. The results are obtained as continuous recordings that are resolvable into both a depth expression and a conductivity effect, so that the indications are easier to evaluate, as well as to correlate from one flown line to the other. The prospecting technique adopted in our electric airborne surveys may be brie fly described as follows: A loop of many turns of insulated copper cable is fastened around the fuselage of the &apos;plane and connected to a generator supplying a few ampere alternating current, usually of a frequency less than 1,000 cycles per second. Just as the current in the primary coil of a common transformer will induce current in the secondary coil when shorted, the alternating magnetic field from this primary current now induces alternating current in electric conductors that happen to be located in the vicinity of the path over which the &apos;plane is flown. This induced secondary current in each conductive section of the ground causes, in turn, an alternating magnetic field, secondary field, which disturbs or dampens the normal alternating magnetic field from the primary loop flown by the &apos;plane. These secondary fields are then picked up and recorded by the help of detecting solenoids, amplifiers, and recorders carried in the &apos;plane. By closer study of such a secondary field it is possible to localize the secondary current causing it and, thereby, the conducting body that contains the secondary current. In the &apos;plane are continuously recorded, besides the amplitude or intensity of the field, also the phase, which is a measure of how much the recorded secondary field is out of step with the primary field.

Jan 1, 1950

By C. Bernier

This paper deals with three major problems associated with mining operations during the winter. These are the maintenance of the cooling systems of diesel engines, the high incidence of hydraulic dump failures on packaging machines, and the build-up of frozen fines on wet-ore conveyor belts.

Jan 1, 1966

By A. B. Rossetti

"THE MISSION TO Offshore Scotland was in my opinion a very worthwhile venture, as it indicated the scope of the offshore oil and gas business and how we might exploit it to the fullest here in Nova Scotia - if our offshore fields eventually become producing fields. The writer was able to attend a considerable number of lectures and as a result gained some valuable know-how on the engineering design, financing and operation of the North Sea oil industry. There are many new fields of technology that had to be developed to overcome the North Sea's hostile environment and a great deal of the same technology will have to be developed to win oil and gas from our continental shelf. The visit left me with several impressions, which in the main are:(1) The high order of investment required to develop offshore oil. The investment ranges from 10 to 20 times that required for a similar output on land. Each barrel of oil costs on the average of about $2,- 500 per barrel per day.(2) Because of the high investments required, before the first oil is produced the field must be brought into production at the earliest possible date and initial lead time from decision to production is less than four years. In the British Petroleum field, working at a depth of 450 feet will require an investment of $900,000,000 to develop a production of 400,000 bbl per day. (3) The size and complexity of equipment required is beyond anything ever imagined. Problems which must be overcome are such factors as water depth, wind velocities, wave height, wave period, long periods of darkness, low temperatures, distance from land, and fog."

Jan 1, 1973

By W. F. MacIsaac

"The large low-grade Copper Mountain deposit is located in the northern portion of the Gaspé Cooper Mines property. It is approximately 1 mile north of the Needle Mountain deposit. The orebody outlined to date lies in the top 1,000 feet of the Grande Greve formation. Chalcopyrite occurs in association with pyrite and quartz in small veinlets and numerous fractures. The deposit is immediately adjacent and parallel to a quartz-feldspar dyke and may be associated with a nearby porphyry stock. Stratigraphy, alteration and structure appear to have played an important role in ore deposition."

Jan 1, 1969

By C. Barlow

The White Mesa Mill (WMM) began operating in 1980 as a regional processing mill owned by Energy Fuels Nuclear, Inc. Original mill design was for 656,000 Mtpa of U ore producing 1,250 tpa of U3O8 concentrate. Sustained market downturns delayed facility upgrades during most of the 1980s and 1990s. The new owners of WMM, Denison Mines, elected to advance the regional mill concept in 2007 with the modernization of these facilities. This paper details decisions taken and lessons learned in plant redesign, choice of leading-edge instrumentation, motor controls and process automation, training and some example benefits from process control stabilization.

Aug 1, 2010

By Peter Moser, Thoma Oberndorfer

"Within the research project “Mine Development” (Fettweis and Moser, 1990) a PC-based mine database has been built up since 1991 and so far includes detailed technical and economic data of about 150 under-ground hardrock mines in industrialized countries worldwide. These data represent about 50% of the underground hardrock mines in west and central Europe, Scandinavia, United States, Canada and Australia (Fig. 1). The mining operations included in the database have been visited directly and analyzed with respect to their deposit conditions, their general design and layout and also their operational and economic performance.The main aim of the Mine Database is to make a contribution to an improved planning of new underground hardrock mines. An analysis of current mine planning practices shows, that both personnel and company experience is still a dominant factor in planning new underground hardrock operations. Through the information included in the Mine Database the experience of a single per-son or company is supplemented by the experience of a wider group of people. The Mine Database makes the huge amount of experience that is available worldwide in the field of under-ground mining accessible for new mining projects. From that a contribution to a more reliable mine planning procedure based on the performance of existing mining operations is expected.In addition to its use in planning new mining operations, the Mine Database can con-tribute to the exchange of technical data among different mining operations, especially on equipment performance, etc. Such an information service is offered by the Department of Mining Engineering & Mineral Economics in Leoben and is already being used by different mining companies. To respect proprietory information, company specific information is not released under any circumstances.The cost of building up the Mine Database, so far, is about US$500.000 — two thirds of which is labour, and one third, travel."

Jan 1, 1996

By Jared Onyirimba, Jim Viellenave, Hal Demuth, Dale Verran, Chad Sorba, Errol Lawrence, David Bronkhorst

As outlined within the Denison Mines Corp’s (“Denison”) Pre-Feasibility Study ("PFS") completed in late 2018, additional work is required to increase confidence and reduce risk associated with the application of the In-Situ Recovery (“ISR”) mining method at the Phoenix deposit, located on the Wheeler River Uranium Project (“Wheeler River” or the “Project”) in northern Saskatchewan. The successful application of ISR in any geological environment largely hinges on three fundamental requirements, 1) permeability (of the deposit), 2) containment (of the mining solution) and 3) leachability (of the mineralization). Denison has designed several staged technical programs to progressively reduce risk associated with these requirements as the Company advances the Project toward a Feasibility Study (“FS”) and Environmental Impact Assessment (“EIA”). This paper will discuss the scope and results of certain technical programs being undertaken as the Company aims to develop the first ISR mining operation in the Athabasca Basin.

Jan 1, 2020

By M. Oliazadeh

The bioleaching of fine low grade copper sulfide ore is described. A sample of ground (> 1 mm) copper ore from Sarcheshmeh, Iran, was subjected to a series of agglomeration procedures and subsequently leached. The best agglomerate was obtained by using lime and sulfuric acid as binders. A column bioleaching test of agglomerated ore was then run for 105 days along with a non-inoculated control column having thymol as bactericide. The results show that about 77.5% of copper was extracted in the bioleaching, whereas the control column achieved only 57% copper leaching.

Jan 1, 2007

By Haofeng Xie, Lijun Peng, Xujun Mi, Xue Feng, Xiangqian Yin, Zhen Yang, Guojie Huang

The Cu/Al composite wires have been widely used in cable industry. Especially in the development of aerospace, the light weight character of wires is particularly important. The wires are fabricated by a drawing process and heat treatment. Mechanical and electrical properties are measured and analyzed. The bending behavior is studied by scanning electron microscope. INTRODUCTION Cu/Al composite is a typical bimetallic composite that has been used in plenty of fields such as automobile and aerospace. The composite has the advantages of excellent conductivity as well as low weight, which cannot be obtained from single copper or aluminum. Industrial products of Cu/Al composite include Cu/Al composite joints (Uscinowicz, R., 2013), Cu/Al bimetallic sheets (Li, X. et al., 2011), Cu/Al flat bar (Wu, Y. & Liu, X. & Xie, J., 2014) and CCA wires (Ahmed N., 1978). CCA wires refer to the composite wires that copper layer concentrically coated on the surface of aluminum core conductor, implementing solid combination of two metals on the interface and forming an integral. At present, the aircraft cable generally use copper or copper alloy conductor, which makes the wire in the aircraft occupy a considerable proportion due to the large density of copper. Therefore, the use of Cu/Al composite wires instead of copper wires for weight loss, is of great significance to the development of aerospace technology industry. Heat treatment is an indispensable procedure to improve plasticity during cold working process, which is of great importance to preparation of wires (Wang, Q. et al., 2008). During the heat treatment, the Intermetallic Compounds (IMCs) are inevitable formed at the contact area of Cu/Al due to the occurrence of diffusion (Lee, S. et al., 2012). According to the results of former researchers, kinds of IMCs were discovered. Antoine Gueydan (2014) identified the formation of three IMCs (Al2Cu, AlCu, and Al4Cu9) at the interface between copper and aluminum after thermal aging. IMCs have a significant effect to the properties of Cu/Al wires. Bending performance is a vital property for the actual application of wires. The brittle IMCs may create a stress concentration that can cause crack initiation during bending process. This work focus on the mechanical properties of Cu/Al composite wires after heat treatment. The effect of various annealing condition on mechanical and electrical properties are studied, in order to find the appropriate annealing conditions, which produce optimal combination properties of Cu/Al clad composite wires. Bending fracture of composite wires is discussed by morphology observation.

Jan 1, 2019

By R. C. E. Bray, Peter Price

"The property of Pamour Porcupine Mines, Limited, is in the eastern Porcupine area, about 12 miles northeast of Timmins. It covers parts of lots 3-6 (inclusive), cons. 5 and 6, Whitney tp., Cochrane district, Ontario. It is an amalgamation of the old La Palme, Three Nations, and Porcupine Grande properties.The first discovery on the Pamour was made in 1911. During 1911 to 1914 a small shaft was sunk on the Three Nations vein to the 200-foot level and a 100-ton stamp mill was put in operation, but only a small production was achieved. The property remained idle from 1914 to 1923. In 1924 some diamond drilling was done along the Keewatin-Timiskaming contact with some encouraging results, but the gold mineralization encountered was too low in general at the price of gold then prevailing to warrant further · work. The increase in the price of gold revived interest in the area, and the above noted amalgamation was effected in 1934. Options were taken and successively dropped by two large mining companies. Following this, exploration both on the surface and underground was started by Quebec Gold Mining Corporation, Limited. Diamond drilling in the early part of 1933 showed considerable ore in conglomerate and greywacke to the east. In the middle of 1935 Noranda Mines, Limited, assumed control and management. A new shaft was sunk and the property was ·equipped with a mill having an initial capacity of750 tons a day. This was subsequently enlarged to 1,500 tons a day.From the commencement of milling (May 16, 1936) to the end of 1946, 5,025,545 tons of ore having an average grade of 0.1327 oz. a ton ($4.64 at $35 an oz.) have been mined and milled."

Jan 1, 1954

By Yosuke Ota, Makoto Tawara, Tetsuya Kojima

"Dry-lube has been used in Europe to enhance formability of aluminum sheet for automotive applications, but it is difficult to ensure degreasing performance with lower degreasing bath temperature. However, newly developed, highly lubricating pre-coats utilizing a urethane resin, which is soluble in water, have been found to show excellent degreasing performance. Furthermore, a richer pre-coat weight coincides with a lower friction coefficient and better formability. Combined use of anti-rust liquid oil showed different friction coefficient depending on applied surface pressure.INTRODUCTION The global demand for aluminum alloy products, especially for automotive application, has been increasing because aluminum alloys can offer excellent corrosion resistance with good strength and low density compared with steel. Aluminum alloys can contribute to saving much more energy and greenhouse gas emissions over the lifetime of the product. On the other hand, the amount of aluminum alloys in vehicle architectures is still somewhat limited due to relatively low formability. As a consequence of this low formability, it is necessary to set a certain limit to the shape of an aluminum alloy panel for automotive applications. So far hot melt wax dry lubricants have been in use especially in Europe as they have been recognized to provide better lubrication than conventional rust protection oils (Meiler & Jaschke, 2005). The benefit of hot-melt wax for automotive manufacturing is associated with a more stable forming process and the possibility to avoid extra lubrication in the press shop. But because of the low poorer solubility of hot-melt wax in degreasing aqueous bath solution, a higher degreasing temperature is required so that no remnant of hot melt wax can be carried over to the next manufacturing process. This temperature control is difficult to impress upon a manufacturing degreasing bath originally designed for liquid oil, especially in Japan. The typical temperature of degreasing bath in Europe is around 60°C, while it is only around 40°C. in Japan. Various types of pre-coats other than hot-melt with high lubricity have been reported (Tawara, 1993; Ueda, Hatsuno & Totani, 2013), but a balance between sufficient degreasing performance and high lubricity has not yet been achieved for an actual production process line."

Jan 1, 2018

By D. W. Li

Due to the ultrasonic testing and mechanical wind speed sensor have high requirement for the environmental of the coal mine, the charge induction wind speed detection method based on wavelet analysis is proposed. The same wavelet disturbance detection method is used at a fixed distance to obtain an induction signal to obtain a pass time, and then calculate the magnitude and speed of the wind. Simulation and verification experiments show that the method has application across a wide range of test speeds (up to 60 m/s). The metal probe causes little pipeline flow field interference. The method is particularly well-suited to dusty environment, and does not cause dust deposition through long-term operation. It can be widely used in coal mines for point wind speed continuous online testing.

Aug 1, 2013

By Randy Settgast, Daniel Moos, Hyunil Jo, Ghazal Izadi, Christine Baba

"Analyses of production logs of multiply fractured horizontal wells in unconventional plays show that only a small percent (~30%) of perforation clusters contribute to production. We present in this paper one possible approach to mitigating this problem, based on use of a fully 3-D numerical model of fracture propagation through a heterogeneous medium, by studying the influence both of spacing and of perforation friction on the initiation and propagation of simultaneous hydraulic fractures from a horizontal wellbore. The results indicate that while limited-entry perforating can help to equalize the lengths of fractures simultaneously growing from multiple clusters, it cannot equalize their widths. Both fracture width and fracture length can be equilibrated by combining non-even cluster spacing with limited-entry perforating. This has obvious benefits as it allows equalized placement of proppant across the entire series of perforation clusters, resulting in similar fracture widths and conductivities which enhances the likelihood that all clusters will contribute equally to production.INTRODUCTIONThere is substantial evidence from production logs and other information that during the hydraulic stimulation of horizontal wells, not all perforation clusters within a given stage will produce. One possible cause is the interaction between the hydraulic fractures emanating from each perforation cluster. Typically fractures created at the outer perforation clusters create “stress shadows”, i.e. increases in compressive stress in the minimum principal stress direction, which limit the growth of fractures growing from interior clusters; this is confirmed by modelling [1, 2, 3]. An example of this can be seen in Figure 1 which shows the final configuration of simultaneously propagating fractures from multiple, evenly spaced clusters when there is no perforation friction. The inner fractures are substantially shorter, reproducing the results by Bunger and Peirce [3]. The inner fractures also have substantially smaller widths.One approach to equalize the growth of simultaneously propagating fractures from a horizontal wellbore is by using limited-entry perforating as a method to equilibrate the flow rates into each of the different perforation clusters. Perforation friction is caused by the finite diameter of the entry points into the formation, and leads to a pressure drop across each perforation which is proportional to the flow rate squared. Fractures that take more fluid have a higher fluid velocity through the perforations than fractures receiving less fluid. This causes a larger pressure drop between the wellbore and more rapidly growing fractures, compared to the same pressure drop between the wellbore and the fractures that grow more slowly. Because pressure within the wellbore is approximately the same at each entry point, the larger pressure drop leads to less pressure being delivered to rapidly growing fractures, thereby decreasing their ability to propagate and reducing the amount of fluid they are able to receive. Because the mass rate of injection into the wellbore is constant, this forces more fluid into the fractures that were propagating more slowly, increasing their growth rate. It also increases the pressure required to drive fluid injection. The balance of these effects makes the system largely self-regulating and delivers more balanced fracture growth. While this effect is well known, it is often neglected in current numerical models."

Jan 1, 2015