Outside the Box: Innovative Application of Diversion as a Replacement for Bridge Plug

Effective stage-to-stage isolation is typically accomplished by setting a bridge plug in a properly cemented casing between stages. This isolation plays a vital role in a horizontal well multistage fracturing completion. Failure of isolation not only impacts the well productivity but also wastes fracturing materials. The challenges isolation failure poses for stimulation effectiveness include both detection and remediation. First, there has been historically no reliable and cost-effective solution to detect stage-to-stage isolation onsite. One may only start to realize this problem when inconsistent production is observed. Second, existing remedial actions are seldom satisfying in case of an isolation failure. Most commonly, a new plug is set to replace the failed one. However, because the perforation clusters of an unstimulated stage may create irregularities in well inside diameter (ID) (e.g., casing deformation or burr), there is a risk that the plug will be damaged or become stuck when it passes the perforation area. Also, when the plug passes a perforation cluster, the perforations start to take in the pump-down fluid, which can increase the difficulty of the pump-down job. A novel remedial action uses high-frequency pressure monitoring (HFPM) and diversion to solve both challenges. The stage isolation integrity is evaluated in quasi-real time by analyzing the water hammer after the pump shutdown. In the case of a plug failure, large-particle fracture diversion materials and techniques can establish temporary wellbore isolation through a quick and simple delivery process. To close the cycle, the effect of the diversion can be evaluated by HFPM, which can reveal the fluid entry point of the treatment fluid after diversion. The technique was applied to two cases in Ordos basin in which wellbore isolation failure interrupted the operation. The problem identification, development of the solution workflow, and observation from treatment analysis are discussed. In both cases, the stage-to-stage isolation was recovered, and the drilled sand body was successfully stimulated without involving costly and time-consuming well intervention. The stimulation operation of the entire well was successfully resumed in a timely manner.

Finite element modeling of sub-surface damage while machining aluminum based metal matrix composites

Sub-surface damage during machining of aluminum-based metal matrix composites (MMCs) has been modeled using finite element models. These models are based on reinforcement particles size and volume fractions and particles are distributed uniformly in the metal matrix. In order to simulate particle debonding cohesive zone elements (CZE) have been incorporated along the parting line. In addition, failure criteria based on brittle fracture have been added for ceramic particles to simulate particle fracture. To reduce computational time and simplify the model both CZE and particle fracture is limited to the reinforced particles along the parting lines facing the tip of the cutting tool. The damage depth beneath the machined surface is measured by using the non-zero plastic strain values in the equivalent plastic strain contours obtained from the FE models. The results were compared against published experimental data and found to be in good agreement.

Experimental analysis and numerical modeling of particle embedment and fracture in the solid particle erosion of ductile materials

Embedment and fracture of abrasives are two often neglected important phenomena that can affect material removal occurring in industrial processes that involve high speed impact of particles on relatively ductile targets. This thesis proposes new methodologies to predict the likelihood of particle embedment and fracture for a typical solid particle erosion application. Double-pulsed laser shadowgraphy was used to measure the instantaneous orientation of angular 89-363 μm SiC particles within a micro-abrasive jet, in order to assess whether their orientation affected the propensity for particle embedment. A tendency for particles to orient with the jet axis was measured and successfully modelled (<9% error), with larger abrasives more likely to orient. The measured instantaneous orientation of particles was used to generate a three-dimensional coupled finite element and smoothed particle hydrodynamics model capable of simulating the particle embedment. Use of various combinations of process parameters yielded embedment predictions that agreed with measured ones with, at most, a 16% error. Increases in particle size, orientation angle, and velocity were found to enhance the propensity for embedment. Double-pulsed laser shadowgraphy was used to record the impact and fracture of abrasives upon impact. A numerical model that utilized an Element Free Galerkin (EFG) technique with a novel scheme for generating realistic three-dimensional particle geometries was used to simulate the particle fracture. For a wide variety of process parameters, the numerical predictions of particle average size, roundness and rebound velocity agreed with the corresponding measurements to within 10%, at most. The propensity for particle fracture was found to depend on the magnitude of particle kinetic energy perpendicular to the target. It was confirmed that at the same incident velocity, larger particles were more likely to fracture. However, for the same kinetic energy, smaller particles were more likely to fracture. To the best knowledge of the author, this thesis is the first to report measurements of particle orientation and particle fracture in abrasive jets, and the first to develop numerical modeling of particle fracture and embedment. The results have important implications for erosion testing and abrasive jet machining operations.

Experimental analysis and numerical modeling of particle embedment and fracture in the solid particle erosion of ductile materials

Embedment and fracture of abrasives are two often neglected important phenomena that can affect material removal occurring in industrial processes that involve high speed impact of particles on relatively ductile targets. This thesis proposes new methodologies to predict the likelihood of particle embedment and fracture for a typical solid particle erosion application. Double-pulsed laser shadowgraphy was used to measure the instantaneous orientation of angular 89-363 μm SiC particles within a micro-abrasive jet, in order to assess whether their orientation affected the propensity for particle embedment. A tendency for particles to orient with the jet axis was measured and successfully modelled (<9% error), with larger abrasives more likely to orient. The measured instantaneous orientation of particles was used to generate a three-dimensional coupled finite element and smoothed particle hydrodynamics model capable of simulating the particle embedment. Use of various combinations of process parameters yielded embedment predictions that agreed with measured ones with, at most, a 16% error. Increases in particle size, orientation angle, and velocity were found to enhance the propensity for embedment. Double-pulsed laser shadowgraphy was used to record the impact and fracture of abrasives upon impact. A numerical model that utilized an Element Free Galerkin (EFG) technique with a novel scheme for generating realistic three-dimensional particle geometries was used to simulate the particle fracture. For a wide variety of process parameters, the numerical predictions of particle average size, roundness and rebound velocity agreed with the corresponding measurements to within 10%, at most. The propensity for particle fracture was found to depend on the magnitude of particle kinetic energy perpendicular to the target. It was confirmed that at the same incident velocity, larger particles were more likely to fracture. However, for the same kinetic energy, smaller particles were more likely to fracture. To the best knowledge of the author, this thesis is the first to report measurements of particle orientation and particle fracture in abrasive jets, and the first to develop numerical modeling of particle fracture and embedment. The results have important implications for erosion testing and abrasive jet machining operations.

Fracture, aggregation and segregation in dry, granular flows

Particle fracture, the formation of small particles as the result of the breakage of large ones, and aggregation, the formation of large particles as the result of the combination of small ones, have important implications in industry (e.g. food processing, pharmaceutical production) and geophysics (e.g., snow avalanches and rock debris flows). Also, the presence of particles of different size that result from fracture and aggregation can induce segregation, resulting in the migration of large and small particles to different regions of the flow. Here, we formulate simple models for fracture and agglomeration and analyze the evolution of measures of the relative concentration of two sizes of spheres due the combined effects of fracture, aggregation, and segregation in dense, dry, granular flows. Particle breakage and combination is influenced by the frequency of collisions, by the local number density of the spheres, and by the particle kinetic energy. Segregation is predicted using a kinetic theory proposed by Larcher & Jenkins [2].

Stress and force measurement uncertainties in 3D granular materials

We have developed and employed a 3D particle stress tensor and contact force inference technique that employs synchrotron X-ray tomography and diffraction with an optimization algorithm. We have used this technique to study stress and force heterogeneity, particle fracture mechanics, contact-level energy dissipation, and the origin of wave phenomena in 3D granular media for the past five years. Here, we review the technique, describe experimental and numerical sources of uncertainty, and use experimental data and discrete element method simulations to study the method’s accuracy. We find that inferred forces in the strong force network of a 3D granular material are accurately determined even in the presence of noisy stress measurements.

Bulk boron doping and surface carbon coating enabling fast-charging and stable Si anodes: from thin film to thick Si electrodes

To address the particle fracture and loss of electrical connectivity of high capacity silicon anode, herein, we propose a novel strategy that combines surface carbon coating and bulk boron doping....

Reversible planar gliding and microcracking in a single-crystalline Ni-rich cathode

High-energy nickel (Ni)–rich cathode will play a key role in advanced lithium (Li)–ion batteries, but it suffers from moisture sensitivity, side reactions, and gas generation. Single-crystalline Ni-rich cathode has a great potential to address the challenges present in its polycrystalline counterpart by reducing phase boundaries and materials surfaces. However, synthesis of high-performance single-crystalline Ni-rich cathode is very challenging, notwithstanding a fundamental linkage between overpotential, microstructure, and electrochemical behaviors in single-crystalline Ni-rich cathodes. We observe reversible planar gliding and microcracking along the (003) plane in a single-crystalline Ni-rich cathode. The reversible formation of microstructure defects is correlated with the localized stresses induced by a concentration gradient of Li atoms in the lattice, providing clues to mitigate particle fracture from synthesis modifications.