Impermeable Screen Research Articles

Parameter substantiation of supra bit jet pump for productive formation opening

The purpose of the study is to develop a supra bit jet pump taking into account the unsteadiness of low-speed drilling for crushing the cuttings injected from the annular space under productive formation opening. The article proposes a device for drill string bottom assembly intended for the initial opening of the productive formation. The device includes a supra bit jet pump and a colmatator. The jet pump creates an additional circulation loop of the drilling fluid above the well bottom, crushes the cuttings injected from the annular space in the mixing chamber and delivers it to the colmatator. An additional circulation loop above the well bottom creates a local drawdown of the formation while maintaining the hydrostatic pressure in the well. Crushing of cuttings in the mixing chamber of the jet pump occurs due to the creation of cross flows in the jet pump. The cross flows are provided due to the angular and eccentric displacement of the working nozzle of the jet pump relative to the mixing chamber. The colmatator creates an impermeable screen on the borehole wall for temporary isolation of the productive formation under initial opening. The conducted study allowed the authors to propose head characteristics of the jet pump taking into account the angular, eccentric displacement of the working nozzle. The head characteristic of the jet pump has been developed for the unsteady operation of the jet pump in the drill string bottom assembly. The head characteristics take into account the roughness of the flow path of the jet pump. Using the head characteristics, the permissible displacements of the working nozzle of the jet pump have been determined. Recommendations for the design of jet pumps for drill string bottom assemblies are proposed.

Methods for calculating the balance during the period of draw-off, drainage of sludge collector cells and construction of secondary embankment dams

An industrial waste-phosphogypsum-is formed in the production of phosphorus mineral fertilizers. As is well-known, the issues of processing and utilization of phosphogypsum on an industrial scale remain unsolved. Consequently, production waste generated at chemical plants is stored in various types of storage tanks. The currently used hydraulic storage method provides for the supply of waste in the form of a slurry into the hydraulic dump cells, their sequential dehydration in the dump, and the subsequent development of a part of the stored waste for the construction of secondary dams. However, due to the low water-release properties of phosphogypsum, it is impossible to ensure its dehydration to the required degree, in large volumes, and the required period. Therefore, various designs of watertight diaphragms and drainage devices are provided in the sludge collector to accelerate the process of dehydration of the phosphogypsum strata. The balance of the sludge collector should be assessed in two periods: the initial period when the sludge collector cells are filled, bounded by the primary dam, and the subsequent period when the reservoir is built up by erecting secondary dams from the stored material. In the initial period, the operating mode of the sludge collector is divided into two stages: in the first stage, a pond is formed above the layer of sludge with a certain predetermined depth; in the second stage, this depth of water in the pond is kept constant by the spillways. The second build-up period is preceded by a period of cell preparation, namely: the draw-off of the pond and drainage of the cell to a moisture content suitable for the dam filling and normal operation of the mechanisms used in the construction of dams. This article presents the results of filtration studies in sludge collectors with an impermeable screen (made of polymer film, asphalt-polymer concrete, etc.) above the screen drainage system. The calculating methods for the determination of filtration parameters in the second period of operation are described: when the pulp supply stops, and a pond of clarified water with a depth of H0 is drawn off.

DYNAMICS INTERACTION OF THE SHARE MOLE PLOW WITH SOIL IN THE FORMATION OF THE CAVITY FORIMPERVIOUS SCREEN

To maintain moisture and best spread it in the horizontal direction under in-soil irrigation of agricultural plants there is a necessity of laying moisturizers together with an impermeable screen. For this purpose, share mole plow can be used. Substantiation of tool's geometrical parameters and modes of operation is an actual scientific problem. Solution of this problem requires formalizing the soil as the medium on which the tool is directed, as well as formalizing the interaction of the tool with the soil. This article discusses the dynamics of the ploughshare forming a horizontal gap into which the anti-filter screen extends. For this, the interaction of the plowshare of the mole with the soil in the contact zone during compaction of the walls of the formed cavity is under considered. Herewith, the degree of compaction of the walls affects the stability of the arch of the formed cavity. During the study, the soil is presented in the form of an elastic viscous deformable medium, and the ploughshare - in the form of an absolutely solid. The surface of this solid is described by a three-dimensional equation in an implicit form, the coefficients of which characterize the geometric parameters of the tool. In a previous article, the authors obtained functions of the rates of soil deformations from the action of the tool. Based on the strains functions with use the physical equations of the connection between stress and strains, the functions of the stress components on the mechanical properties of the soil and the parameters of the tool are obtained. The stress components obtained in the contact zone of the plowshare with the soil made it possible to determine the function of changing the specific volume of the soil. This function is inversely proportional to soil density. The use of equilibrium equations on the contact surface made it possible to determine the components of the forces that act from the soil side on the ploughshare. Integration of the obtained components of the distributed forces over the ploughshare surfaces made it possible to obtain the sum of the resistance forces to the ploughshare movement, depending on the mechanical properties of the soil and tool parameters. As a result of the study, rational parameters of the equation coefficients of the ploughshare surface that characterize its geometric parameters are determined.

Stress state analysis in the vicinity of the hydraulic fracturing tool located near the bottom of the well

ABSTRACT Hydraulic fracturing is a widely used method in the mining industry. In the case of underground workings, the formation of parallel fractures across the borehole axis is of great particular interest for many geotechnical issues, for example, improving the production of coal seam gas or making an impermeable screen in massif to eliminate a water inflow. The article presents a hydofrac tool’s scheme with one inflatable packer promoting the creation of transverse crack. We observe in the laboratory the behaviour of the packer to estimate the displacement of its sliding end when the pressure was applied. These data were used to assess the possibility to form a fracture in the desired direction. In addition, numerical studies of the stress state caused by loading, created with the help of the downhole tool, have been carried out. Analysis of parameters necessary for the formation of an initial crack on the borehole wall is presented. Results show that the using of the borehole tool equipped with an anchoring module allows to create conditions for the appearance of a transverse initiating crack. It has been established that a decrease in the length of the anchor leads to an increase in the tensile axial stresses.

On Ground Water Flow to an Imperfect Gallery: Case of Evaporation from a Free Surface

The plane steady-state filtration in a phreatimetric formation to an imperfect gallery in the presence of evaporation from the free surface of groundwater is considered. In order to study the evaporation effect, a multiparameter mixed boundary-value problem of the theory of analytic functions is posed and solved by the Polubarinova-Kochina method. Based on the proposed model, we develop an algorithm to compute the seepage flow characteristics and provide the hydrodynamic analysis of the impact of the dependences of all the physical parameters of the scheme on the flow rate of the gallery and the ordinate of the exit point of the depression curve on an impermeable screen.

On the Problem of Filtration to an Imperfect Gallery in a Pressureless Bed

The problem of plane steady-state filtration in a pressureless bed to an imperfect gallery in the presence of evaporation from the flow free surface is considered. To study such type of flow, a mixed boundary-value problem of the theory of analytical functions is formulated and solved with application of the Polubarinova-Kochina method. Based on the model suggested, an algorithm for computing the discharge of the gallery and the ordinate of free surface emergence to the impermeable screen is developed. A detailed hydrodynamic analysis of the influence of all physical parameters of the model on the desired filtration characteristics is given.

Microclimate and agronomical effects of internal impermeable screens in an unheated Mediterranean greenhouse

In unheated greenhouses in mild-winter areas, low-cost, fixed, water-impermeable plastic screens are frequently installed in winter cycles of the vegetable crops more sensitive to fungal diseases. They are used to prevent rain and condensation falling on the crop and to improve the greenhouse air temperature. Two experiments were carried out to quantify how fixed and movable impermeable screens affect microclimate and crop behaviour in an unheated greenhouse in a mild-winter area. The fixed screen improved the night-time temperature and humidity of the air below the screen, and reduced the water condensation on its inner plastic surface or the proliferation of fungal diseases, but did not completely prevent it. Compared to the greenhouse without screen, the movable screen, usually unfolded at night, increased the night-time temperature of the air and the crop, reduced the night-time relative humidity of the air below the screen, prevented the water condensation on the screen or the crop, accelerated melon crop development, and significantly increased early marketable yield of melon fruits and their quality, but it did not substantially affect the substrate temperature, or the total marketable yield of melon fruits. In the comparison of the greenhouse with fixed versus movable screen, no substantial differences were found for a winter cucumber cycle in night-time temperature and relative humidity of the air below the screens, in shoot biomass or in fresh weight of total and marketable cucumber fruits. This can be mainly attributed to the small differences between both treatments in the shortwave radiation reaching the crop.

Применение непроницаемых экранов для стабилизации течения в угловом регулирующем клапане

Применение непроницаемых экранов для стабилизации течения в угловом регулирующем клапане

Results of comprehensive studies of the underground hydrosphere within the western shoulder of the Baikal rift (as exemplified by the Bayandai - Krestovsky Cape site)

Results of comprehensive studies of the underground hydrosphere within the western shoulder of the Baikal rift (as exemplified by the Bayandai - Krestovsky Cape site)

Drainage in ground water flow over a screen

The paper deals with construction and investigation of a mathematical model for ground water flow from the earth's surface over a vertical impermeable screen with flow interception by a drain located on the screen surface.

Le karst des Arbailles (Pyrénées-Atlantiques, France)

THE MASSIF OF ARBAILLES (WEST PYRENEES). The Arbailles massif (200 -1 200 m) is located in the french north face of Pyrenees, Atlantic side. It forms a folded 165 square-kilometres unit of jurassic and cretaceous limestones under an oceanic climate of altitude (2000 mm/year). Observations jointly made on the surface and in the numerous underground galleries allow an occurate correlation of alternate surrective and karstic periods. The dismantled cavities and deposits pockets of the upper surface show two series of minerals, those from weathered marly-albian limestones and others supplied from the conglomerates pudding-stones of Mendibelza. During the Miocene, the Arbailles massif is a low area of tropical erosion on the side of the main mounts. Its surrection caused the scouring of the alterites cover, the formation of fields of karstic butts and a definitive drying of the fluviatile paleosystem. The different levels of dried valleys and the karstic hydrographie systems are successive stations of the karstic levels of origine. Paleomagnetic datations in Etxanko Zola and U/Th datations in Nébélé show that the surrection has been of about 500 m since lower Pleistocene. At the present time, water collection is made throught drainage systems without any connection to the fossil topography. Three aquifers can be distinguished : in lower cretaceous, in jurassic and in north and south limits. They are water-repellent because of more or less impermeable screens. Waters are agressive in summer and at equilibrium or lightly undersaturated the rest of the year. The modern human activities creates a recent destabilization of the environment with local erosions of grounds and an increasing turbidity of springs. An occurate study in the fail of Istaurdy allows a mesure of the effect of deforestation for the whole massif

Measurements of curvature in an ionic model of cardiac tissu

To quantify the effect of curvature on propagation in ventricular cardiac muscle we selected two cases of propagation where wavefronts of pronounced curvature were present: propagation through a narrow hole in an impermeable screen, and propagation after point-stimulation in a homogeneous medium. Those two situations were simulated in a computer model of a two-dimensional isotropic medium incorporating the Luo-Rudy equations to describe the ventricular muscle membrane. A planar wave initiated in the proximal side of the screen was diffracted at the hole creating a curved wavefront. Its propagation velocity beyond the hole first decreased and then increased as it propagated away from the hole. The minimum velocity of propagation was a function of the hole size. When the size of the hole was smaller than 175 μm, propagation through the hole was impossible. After point stimulation in a homogeneous medium a wavefront with a circular shape was initiated. The velocity of the propagating wave increased as the radius of the wavefront increased. To initiate a propagating wave, a circle with a diameter of 450 μm had to be activated. Considering the reciprocal of half the size of the hole as an estimation of the maximum curvature imposed by the hole, and the reciprocal of the radius of the wavefront as the curvature in the case of point-stimulation, in the two cases studied the propagation velocity decreased linearly with increasing curvature. Wavefronts whose curvature was higher than a critical value did not propagate. Therefore, in cardiac ventricular muscle, the curvature of the wavefront can be a cause of slow conduction and block.

On the diffraction of autowaves

The paper is concerned with the passage of autowaves through one or two holes in an impermeable screen, their diffraction at a screen edge, and their passage through narrow channels in a thick screen. The following interesting phenomena were observed: aperiodicity in wave trains behind the screen (chaos) and frequency demultiplication in the case of a periodic train of autowaves incident on a narrow hole in an impermeable screen; the effect of autowave reflection from a hole; the possibility for a narrow channel to become a source of periodic autowaves. The studies were performed by numerical experiments with a model of an excitable medium of the FitzHugh-Nagumo type.

Economic geology of the Mishraq native sulfur deposit, northern Iraq

The Mishraq native sulfur deposit is in northern Iraq about 40 km southeast of Mosul and 315 km north of Baghdad. This deposit is the largest known occurrence of stratiform bioepigenetic sulfur, containing at least 100 million tons of elemental sulfur. It underlies a 10 km 2 portion of the southeast end of a northwest-trending, doubly plunging anticline on the west bank of the Tigris River at its confluence with the Great Zab River. The deposit is in one anticline among many in the folded portion of the Mesopotamian depression and represents part of what may be the largest reserve of elemental sulfur in the world.Small, tight, en echelon folds are superimposed on the southwest limb of the Mishraq anticline with axial trends similar to the main fold (320 degrees ). Faulting is normal and reverse with dominant northwest and subordinate northeast trends. Mining-induced subsidence of 4 to 5 m causes fractures which tend to follow these preexisting directions.The sulfur mineralization is in three main zones of vuggy and bituminous bioepigenetic limestone in the basal Lower Fars Formation of middle Miocene age and marine origin. The Lower Fars consists of intercalated bituminous marine carbonates (dolomite, limestone, marl) and anhydrite/gypsum with minor shale and sandstone interbeds. The depositional environment was of periodic marine influxes followed by evaporation in a partially barred basin with southern access to the sea.The sulfur forms by oxidation of hydrogen sulfide produced during metabolysis of petroleum and anhydrite/gypsum by anaerobic bacteria (D. desulfuricans), a conclusion supported by the 34 S and 13 C fractionation data. Sulfur mineralization is thickest in areas of intense folding and faulting which enhance solution, movement, and mixing of reactants. Combined thickness of the three sulfur-bearing zones is from 2 to 123.9 m, with a maximum ore section of 107.9 m and a grade of 23.14 wt percent sulfur. Seven ore types have been recognized of which predominant coarse crystalline sulfur alternates with bands of secondary limestone.Hydrologic conditions at the mine are complex with subsurface drainage via karst features, fractures, faults, and vuggy porosity within the ore zones of the productive member. The productive member contains the bulk of the ground water, although up to 13 aquifers have been recognized throughout the section, and it is intersected by the Tigris River. A very steep hydraulic gradient exists with flow southeastward toward the Tigris where it is discharged from springs in and beside the river. Hydrogen sulfide-carbonate waters predominate. Recharge is mainly at the northwest portion of the anticline where the Lower Fars crops out. The ground water connection and flow to the river is important in sulfur generation as it is the pathway by which oxygen is carried into contact with hydrogen sulfide at depth yielding sulfur and water.The deposit is currently being mined by the Polish hydrodynamic (modified Frasch) process at a rate of about 600,000 tons per annum out of a total capacity of 1,000,000 tons per annum. The maximum capacity has not been reached because of infrastructural constraints related to transportation and because the mine is difficult to operate. Large injection water losses and excessive bitumen contamination are paramount. Water losses are mitigated by the installation of subsurface impermeable screens. Bentonite/sulfuric acid filtration removes the excess bitumen but at a cost of 8 to 25 percent loss of sulfur in filter cake and skim foam.Initially sulfur was vatted at the mine, crushed, and shipped via rail to the port of Um Qasr about 1,000 km south of Mishraq. Liquid sulfur is currently shipped to the port where vatting is done as necessary.