Abstract The recent development of unconventional oil and gas reservoirs has been accompanied by a rapid expansion in hydraulic fracturing technology. A successful stimulation treatment relies heavily on the performance of the proppant used. Proppant performance has been quantified thoroughly in a laboratory setting for over 30 years through the procedures outlined in API RP61 and later API RP19D, referred to as the short-term test and long-term test, respectively. These procedures produce variable results from test to test, person to person, and lab to lab. As a result, a gross variance of ±20% about a mean is considered within laboratory accuracy for the long-term test, although variances of more than 80% have been recorded. This variability is thought to be a consequence of the inconsistent packing structure generated by the cell loading process, which creates a loose, incompact arrangement of proppant grains. The focus of this research was the development of a new cell loading process that creates a more repeatable grain packing structure. Applying vibration to the proppant pack prior to testing was evaluated as a means of rearranging the grains into a denser, more compact structure and in turn decreasing the level of variability. A modification of the procedure defined by API RP19D was used to compare the different cell loading techniques in a timely manner. Five methods of applying vibrational energy were investigated, with successively more refined technologies used as research progressed. Preliminary results were encouraging and led to the development of two vibrational methods that substantially decreased gross variance of conductivity measurements. The cell loading technique outlined in API RP19D produced a variance ranging from 13% to 51%, with an average variance of 31% for the entirety of the stress ramp. Both vibrational methods produced variances below the threshold of 20% throughout the stress ramp, with an average variance of 6% for one vibrational method and 11% for the other. These results demonstrate the potential for a vibration modification to the cell loading process to improve the science of conductivity testing.
Experimental study is carried out on the influence of fly ash fillers on mechanical and tribological properties of woven jute fiber reinforced polymer hybrid composite. Composites were prepared using hand layup method with weight percentage of fly ash as filler material varying from 2% to 10% with 3 ply (0/90)s woven jute fiber as reinforcement having weight percentage of 40%. Considerable improvement in hardness of the composite upon increasing the filler content was observed however the tensile property decreased. The tribological property obtained using pin on disk wear apparatus showed considerable increase in wear resistance of the composite material upon increasing the fly ash as filler material.
In this research work, pulverized biochar obtained by the pyrolysis of rice husk is used as particulate reinforcement in unsaturated polyester matrix. The effects of the particle loading and particle size on tribological properties of the particulate composites were investigated. The average size of biochar particles obtained through pulverizing using ball-mill varied from 510 nm to 45 nm while milling for a duration ranging from 6 hrs to 30 hrs. The particle loading in the composite was varied from 0.5 wt.% to 2.5 wt.%. It was observed that the particle size and particle content played a vital role in the tribological properties of the composites. The specific wear rate of the specimen having particle loading of 2.5 wt.% with 45 nm particle size exhibited a decrease of 56.36% upon comparing with the specific wear rate of cured pure resin. The coefficient of friction of the same sample decreased by 6.42% when compared to that of a cured pure resin. The biochar particles were subjected to X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and atomic force microscope analysis for characterization. Morphological studies were performed on the worn surfaces by scanning electron microscope (SEM) and optical microscopy.
This research work emphasizes using pulverized biochar obtained by the pyrolysis of rice husk as a particulate reinforcement in unsaturated polyester matrix. The influence of particle size and particle loading on the mechanical and dielectric properties of particulate composites were investigated. The mean size of particles obtained through pulverizing using ball mill varied from 510 to 45 nm when milled for a duration ranging from 6 to 30 h. The particle loading in the composite varied from 0.5 to 2.5 wt%. The impact strength of the specimen having particle loading of 2.5 wt% with 45 nm particle size increased by 77.50%, and its dielectric constant increased by 7% when compared to that of cured pure resin; however, the tensile strength decreased. The biochar particles were subjected to X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), and atomic force microscopy (AFM) analysis for characterization. Morphological studies were performed on tested samples by scanning electron microscope.
In the present work, localised heating has been adopted at the damage site of the cold upset materials and the role of this mechanism on the workability has been analysed. Cylindrical specimens containing 96% aluminium and 4% titanium were prepared through powder metallurgy technique with an aspect ratio (height to diameter) of 1 by suitable pressures. A series of cold upsetting test was conducted and the material properties for various preforms initial relative densities (80%, 85% and 90%) were determined under the stable strain rate. The flow of metals was analysed using a finite element tool and it was observed that the metal flow starts from near the centre zone to the equatorial zone and the damage happens in the outer position because of more amount of accumulated stresses and the pores. These stresses and pores decrease the workability of the final component. Hence, the present research is intended to reduce the stresses and minimize the pores by applying a localized heating (100 °C–250 °C) at the equatorial sites of the components and thereby increasing the workability of the material. Also, heating selectively at the equatorial site of the workpiece improves the workability due to change in grain size and it was noticed that the grain size of the developed porous preforms was high for the higher heating conditions due to the growth of the grains. Therefore, the localized heating adopted in this work is a superior method to enhance the workability of the powder samples and this novel technique could be useful in improving the workability of the structural components that have extensive applications in the automobile and aerospace industries.
Purpose: Hydraulic fracturing processes are conducted to create new fractures in a rock to increase the size, extent, and connectivity of existing fractures. The American Petroleum Institute (API) developed two testing procedures for measuring conductivity of proppants in a laboratory setting, namely; the Short-Term Proppant Conductivity Testing Procedure and Long-Term Proppant Conductivity Testing Method. However, these laboratory testing methods have produced inconsistent results, with a significant coefficient of variance of ±80% from one test to the other even with the use of the same proppants and procedures. Thus, this work seeks to use an improved laboratory variance from Montana Tech conductivity measurements to model hydraulic fractures in reservoir simulation to evaluate how it performs or compares with field performance.
Methodology: Montana Tech researchers have developed new proppant conductivity testing methods to lower this variance. These testing procedures showed more consistent results with an average variance of ±7.6% and ±14.3% in ceramic and sand proppants respectively. These tests were all done at laboratory conditions and therefore this work used field production data obtained from the Willison Bakken Formation and an arbitrary high permeability value as a benchmark against the fracture models built using laboratory results from the new methods of measuring proppant conductivity testing by Montana Technological University.
Findings: The conductivity values corresponding with 6,500 psi closure stress obtained for sand and ceramic were 2,133.5 md-ft and 4,870.3 md-ft respectively. The high permeability model recorded an incremental recovery increase of 42% over the unfractured model. Similarly, the laboratory sand and ceramic models had an incremental recovery increase of 12.9% and 33% respectively over the unfractured model. The dimensionless fracture conductivity for the laboratory sand, laboratory ceramic and high permeability models were 1,246, 2,844 and 233,577 respectively. Generally, laboratory conductivity overestimates field performance, however, this work did not show an improvement in modeling fractures using laboratory data as a result of the extremely low porosity and permeability values of the Bakken wells used for the study and the limitedness of the software package used. Simulation of low permeability reservoirs is still an area in development as traditional models often fail to produce results that match the physics. It is possible that as simulation methods for these types of reservoirs improve, the new laboratory data for fracture conductivity will prove beneficial in modeling.
Unique contribution to theory, practice and policy (recommendation): A sensitivity analysis should be performed in Petrel that starts with the laboratory fracture conductivity and ends with infinite fracture conductivity. This would help determine the effect of correctly measuring fracture conductivity. Again, a better technique in Petrel such as using a tartan grid is encouraged to better assess the performance of each of the fractures and lastly, more well data with associated measured porosity and permeability data is suggested for future works.
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