Reduction of Breakdown Pressure by Filter Cake Removal Using Thermochemical Fluids and Solvents: Experimental and Numerical Studies

The process of well cleanup involves the removal of an impermeable layer of filter cake from the face of the formation. The inefficient removal of the filter cake imposes difficulty on fracturing operations. Filter cake’s impermeable features increase the required pressure to fracture the formation. In this study, a novel method is introduced to reduce the required breakdown pressure to fracture the formation containing the water-based drilling fluid filter cake. The breakdown pressure was tested for five samples of similar properties using different solutions. A simulated borehole was drilled in the core samples. An impermeable filter cake using barite-weighted drilling fluid was built on the face of the drilled hole of each sample. The breakdown pressure for the virgin sample without damage (filter cake) was 6.9 MPa. The breakdown pressure increased to 26.7 MPa after the formation of an impermeable filter cake. Partial removal of filter cake by chelating agent reduced the breakdown pressure to 17.9 MPa. Complete dissolution of the filter cake with chelating agents resulted in the breakdown pressure approximately equivalent to the virgin rock breakdown pressure, i.e., 6.8 MPa. The combined thermochemical and chelating agent solution removed the filter cake and reduced the breakdown pressure to 3.8 MPa. Post-treatment analysis was carried out using nuclear magnetic resonance (NMR) and scratch test. NMR showed the pore size redistributions with good communication between different pores after the thermochemical removal of filter cake. At the same time, there was no communication between the different pores due to permeability impairment after filter cake formation. The diffusion coupling through NMR scans confirmed the higher interconnectivity between different pores systems after the combined thermochemical and chelating agent treatment. Compressive strength was measured from the scratch test, confirming that filter cake formation caused added strength to the rock that impacts the rock breakdown pressure. The average compressive strength of the original specimen was 44.5 MPa that increased to 73.5 MPa after the formation of filter cake. When the filter cake was partially removed, the strength was reduced to 61.7 MPa. Complete removal with chelating agents removed the extra strength that was added due to the filter cake presence. Thermochemical and chelating agents resulted in a significantly lower compressive strength of 25.3 MPa. A numerical model was created to observe the reduction in breakdown pressure due to the thermochemical treatment of the filter cake. The result presented in this study showed the engineering applications of thermochemical treatment for filter cake removal.     

Investigations into the Antifungal,Photocatalytic, and Physicochemical Properties of Sol-Gel-Produced Tin Dioxide Nanoparticles

Transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and Fourier transform infrared (FTIR) spectroscopy were applied to evaluate the tin dioxide nanoparticles (SnO₂ NPs) amalgamated by the sol-gel process. XRD was used to examine the tetragonal-shaped crystallite with an average size of 26.95 (±1) nm, whereas the average particle size estimated from the TEM micrograph is 20.59 (±2) nm. A dose-dependent antifun3al activity was performed against two fungal species, and the activity was observed to be increased with an increase in the concentration of SnO₂ NPs. The photocatalytic activity of SnO₂ NPs in aqueous media was tested using Rhodamine 6G (Rh-6G) under solar light illumination. The Rh-6G was degraded at a rate of 0.96 × 10⁻² min for a total of 94.18 percent in 350 min.     

Enhanced Entanglement and Controlling Quantum Steering in a Laguerre–Gaussian Cavity Optomechanical System with Two Rotating Mirrors

Gaussian quantum steering is a type of quantum correlation in which two entangled states exhibit asymmetry. An efficient theoretical proposal is presented for the control of quantum steering and enhancement of entanglement in a Laguerre–Gaussian (LG) cavity optomechanical system. The system contains two rotating mirrors and a coherently driven optical parametric amplifier (OPA). The numerical results show significantly improved mirror-mirror and mirror-cavity entanglements by controlling the system parameters such as parametric gain, parametric phase, and the frequency of the two rotating mirrors. In addition to bipartite entanglement, our system also exhibits mirror-cavity-mirror tripartite entanglement as well. Another intriguing finding is the control of quantum steering, for which several results were obtained by investigating it for various system parameters. It is shown that the steering directivity is primarily determined by the frequency of two rotating mirrors. Furthermore, for two rotating mirrors, quantum steering is found to be asymmetric both one-way and two-way. Therefore, it can be asserted that the current proposal may help in the understanding of non-local correlations and entanglement verification tasks.     

Convergence of an iterative scheme for multifunctions

Recently, Reich and Zaslavski have studied a new inexact iterative scheme for fixed points of contractive and nonexpansive multifunctions. In this paper, we generalize some of their results to Suzuki-type multifunctions.     

Fixed point theorems for mappings with convex diminishing diameters on cone metric spaces

In this work, Cantor’s intersection theorem is extended to cone metric spaces and as an application, a fixed point theorem is derived for mappings with locally power diminishing diameters.     

Radiative properties of matter based on quantum statistical method

We present the preliminary results of our code OPAQS(opacity calculation using quantum statistical model) that is based on the self consistent Hartree-Fock-Slater model for the average atom. The code is capable of performing robust calculations of average charge state, frequency-dependent and mean opacities. The accuracy of the atomic model is verified by comparing the calculations of average charge state with various published results. The monochromatic opacities for iron computed at different sets of temperatures and densities are compared with LEDCOP. The Rosseland and Planck opacities for iron and aluminum are validated with some state-of-the-art codes. The results are in good agreement with the published data.     

Structural and Magnetic Properties of Chemically Synthesized Pd-Modified NiFe2O4 Nanoparticles

Magnetic nanoparticles of NiFe₂O₄-Pd composites have been synthesized using a simple, low cost, sol-gel auto-combustion method. As-prepared samples were sintered at 800 ℃ for 6 h in order to develop the crystalline phase. X-ray diffraction confirmed the spinel structure of the ferrite samples. Structural morphology and size of the nanoparticles were evaluated using a field emission scanning electron microscope. Magnetic hysteresis loops were obtained at 300 and 100 K using a physical properties measurement system. The value of saturation magnetization was observed to decrease at the temperatures with the increase of Pd contents up to 5% but then a sudden rise in saturation magnetization was observed for the addition of 10% Pd in NiFe₂O₄.