Coal fines are highly prone to be generated in all stages of Coal Seam Gas (CSG) production and development. These detached fines tend to aggregate, contributing to pore throat blockage and permeability reduction. Thus, this work explores the dispersion stability of coal fines in CSG reservoirs and proposes a new additive to be used in the formulation of the hydraulic fracturing fluid to keep the fines dispersed in the fluid. In this work, bituminous coal fines were tested in various suspensions in order to study their dispersion stability. The aggregation behavior of coal fines (dispersed phase) was analyzed in different dispersion mediums, including deionized-water, low and high sodium chloride solutions. Furthermore, the effect of Sodium Dodecyl Benzene Sulfonate (SDBS), an anionic surfactant, on fine aggregation in the suspensions was investigated over a wide alkaline range. At a known pH, the results of stability were validated with the proppant pack glass column test and further verified with microscopic images. It was observed that adding SDBS to the hydraulic fracturing fluid keeps the coal fines well-dispersed in the post-hydraulic fracturing flow back and prevents coal fines aggregation, and ultimately helps permeability enhancement. The results show that at a constant pH, as salinity increases, the zeta-potential (an indirect indicator of stability of the coal-water slurry) reduces. Also, a trace amount of SDBS substantially enhances the dispersion stability of coal fines. This enhancement dictates that coal fines will not congregate and will not plug the proppant pack. Furthermore, the results were confirmed by proppant pack glass-column tests and microscopic images, the result of which illustrate much less aggregation when having SDBS added to the suspension. Polymeric surfactants have been used in the field to disperse coal fines. However, it causes the coal matrix to swell and clog the pore throats, thus reducing the permeability. The anionic surfactant, SDBS, has never been tried in field applications to disperse coal fines. The current research demonstrates the considerable potential of SDBS, as a hydraulic fracturing fluid additive, in enhancing the dispersion stability of the coal fines.
Density Functional Theory at the generalized-gradient approximation level coupled with large unit cell method is used to simulate the electronic structure of (II-VI) zinc-blende cadmium sulfide nanocrystals that have dimensions 2-2.5 nm. The calculated properties include lattice constant, conduction and valence bands width, energy of the highest occupied orbital, energy of the lowest unoccupied orbital, energy gap, density of states etc. Results show that lattice constant and energy gap converge to definite values. However, highest occupied orbital, lowest unoccupied orbital fluctuates indefinitely depending on the shape of the nanocrystal.
This study aims to determine the effect of exposure to cigarette smoke with a biofilter of bidara leaf powder on the histology of the liver, lungs and blood viscosity of mice. This test was carried out for 28 days by giving cigarette smoke with a biofilter of bidara leaf powder and observing the histology of the liver, lungs and blood viscosity. The results showed that exposure to cigarette smoke with a biofilter of bidara leaf powder was very effective in reducing damage to the liver and lungs of mice, and also very effective in reducing blood viscosity as in normal mice blood viscosity. The use of Bidara leaf powder biofilter can affect the histology of the liver, lungs and blood viscosity in mice. Bidara leaf powder biofi
... Show MoreThis study investigated the effect of using brainstorming as a teaching technique on the students’ performance in writing different kinds of essays and self regulation among the secondary students. The total population of this study, consisted of (51) female students of the 5th Secondary grade in Al –kawarzmi School in Erbil during the academic year 2015-2016. The chosen sample consisted of 40 female students, has been divided into two groups. Each one consists of (20) students to represent the experimental group and the control one. Brainstorming technique is used to teach the experimental group, and the conventional method is used to teach the control group. The study inst
... Show MoreThe study aims to find out the effectiveness of using the Google classroom educational platform in teaching mathematics curricula from the viewpoint of teachers in the Governorate of Al Dhahirah, Sultanate of Oman. The researcher adopted the descriptive-analytical approach. To collect the needed data, a questionnaire of two dimensions was used. It includes (13) items to measure the effectiveness of using the Google classroom in teaching mathematics curricula from the teacher's point of view and includes (10) items to measure the difficulties of using the Google classroom in teaching mathematics curricula from the teachers' point of view. These tools were applied to (32) male and (31) female as the study sample. They represent mathematics
... Show MoreThe sustainable competitive advantage for organizations is one of the requirements for value creation, which centered on the possession of scarce resources that achieve maximum flows to invest in intellectual capital, if what has been interest in them, measured and employed the way properly and style, so I figured the need for new technologies to enable organizations to measure the intellectual and physical assets and to assess its performance accordingly, so it sheds search light on the measurement of the added value of existing knowledge using the standard value-added factor is the intellectual (value added intellectual coefficient) (VAIC) and to develop a set of assumptions about the extent of the difference between the sample
... Show MoreThe research aims to measure the efficiency of health services Quality in the province of Karbala, using the Data Envelopment analysis Models in ( 2006). According to these models the degree of efficiency ranging between zero and unity. We estimate Scale efficiency for two types of orientation direction, which are input and output oriented direction.
The results showed, according Input-oriented efficiency that the levels of Scale efficiency on average is ( 0.975), in the province of Karbala. While the index of Output-oriented efficiency on average is (o.946).
The tax system, like any other system, as a set of elements and parts that complement each other and are interrelated and interact to achieve specific goals, and is a natural reflection of the economic, social and political conditions prevailing in society, and therefore the objectives of tax policy formulated in line with the objectives of economic policy in general, which means that any change in economic policy clearly affects fiscal policy measures and fiscal policy in particular.
The problem of searching for the impact of foreign direct investment in the Iraqi tax system was focused on the study the of foreign direct investment and therole played in developing and improving the economic reality and its implicatio
... Show MoreThe international financial accounting and reporting standards IFRS/IAS represent the set of rules and foundations that the economic entity must follow in the measurement, presentation, and disclosure of the elements of the financial statements, the implementation of adopting the international financial reporting standards contributes to improving the qualitative characteristics of accounting information, so the current research aims to explain the role of adopting the International Accounting Standard (IAS) in improving the qualitative characteristics as well as analyzing the impact of the adoption of IAS.1 in improving the qualitative characteristics of accounting information within the financi
... Show MoreIn this work, a large part of Baghdad University campus has been selected. The determination of Geoidal height for the local area requires Ground Control Points which both Ellipsoidal and Orthometric heights are known to compute the difference between them. The first step of the leveling process began by selected the Ground Control Points (GCPs) around the area of the work, and then divided them into two groups of the network traverse stations. They were leveled and adjusted depend on the number of the Bench Marks (B.M.s). Total Station TS (Nikon Nivo 5C) and Global Positioning System (GPS-Garmin 78 map) are used to do this application. The aim of the proposed work was to determine the height of the Geoid surface in the study area. The Geoi
... Show MoreThis investigation aims to study some properties of lightweight aggregate concrete reinforced by mono or hybrid fibers of different sizes and types. In this research, the considered lightweight aggregate was Light Expanded Clay Aggregate while the adopted fibers included hooked, straight, polypropylene, and glass. Eleven lightweight concrete mixes were considered, These mixes comprised of; one plain concrete mix (without fibers), two reinforced concrete mixtures of mono fiber (hooked or straight fibers), six reinforced concrete mixtures of double hybrid fibers, and two reinforced concrete mixtures of triple hybrid fibers. Hardened concrete properties were investigated in this study. G