Search Results (3)

Most of the onshore water-flooding oilfield reservoirs have dominant seepage channels dominated by large pores and fractures, resulting in the oilfield being in a period of high water cut. The treatment of this problem needs to be solved by plugging. In the research process, the particle size and suspension of the water-swellable rubber particles were measured, and the effective time of the particles was evaluated; matching relationship. The results show that adding 2000 mg/L polymer to the water-swellable rubber particles can better improve the suspension performance; the performance of the polymer solution will not be affected during mixing and injection. In addition to strong swelling performance, it also has a certain strength and deformability, up to 10 MPa high via pressure and good thermal stability. Compared with the water and oil environment, the chemical degradation phenomenon is significant after soaking in alkaline conditions. Compared with the alkaline environment and the formation water environment, the final expansion ratio of the water-swellable rubber particles in the formation oil environment is as low as 2.5 times, which has the ability to block water. There was no oil blocking feature. When the crack width is too small, particles with excessively large particle sizes may accumulate at the injection end of the core, resulting in failure to inject into the core and fail to achieve the plugging effect. For the treatment of large, fractured pores, it is possible to first inject particles with a particle size of 0.250–0.420 mm to block areas with high permeability, and then inject particles with a particle size of 0.150–0.250 mm to block areas with low permeability. Full article

The use of mechanic waves for assessing structural integrity is a well-known non-destructive technique (NDT). The ultrasound applied in the guided wave in particular requires significant effort in order to understand the complexities of the propagation so as to develop new methods in damage detection, in this case, knowing the interaction between the wave propagation and the geometry of the waveguides is mandatory. In the present work, the wave propagation in rectangular steel rod is presented. In this study, the section dimensions were fixed as 5 × 15 [mm], a typical element of the flexible riser structural amour commonly used in the offshore oil industry. The studies here presented were restricted to [0, 100 KHz] frequencies. This frequency interval is in the range of commercial waveguide equipment commonly applied in ducts in NDT applications. The computation of the dispersion curves is performed by using three different methodologies: (i) analytical solutions, (ii) a method that combines analytical approaches with finite element methods (SAFE), and (iii) experimental method that extracted information from the rod using laser vibrometers and piezoelectric actuators. Finally, two applications based on the dispersion curves determined in the rectangular waveguide are presented to illustrate the possibilities of the curve dispersion knowledge related to the specific geometry in the development and application linked to NDT. The first application consists on showing the possibilities of the techniques that use a fiber grating Bragg cell (FGB) to measure the wave displacement and the second application involves the simulation of pre-fissured prismatic waveguide aimed at searching to induce three characteristic acoustic events. The model was built combining the finite element method and a version of the discrete element method. Full article

Pseudolesions are defined as physiological or paraphysiological changes of the oral normal anatomy that can easily be misdiagnosed for pathological conditions such as potentially malignant lesions, infective and immune diseases, or neoplasms. Pseudolesions do not require treatment and a surgical or pharmacological approach can constitute an overtreatment indeed. This review aims to describe the most common pseudolesions of oral soft tissues, their possible differential diagnosis and eventual related systemic diseases or syndromes. The pseudolesions frequently observed in clinical practice and reported in literature include Fordyce granules, leukoedema, geographic tongue, fissured tongue, sublingual varices, lingual fimbriae, vallate papillae, white and black hairy tongue, Steno’s duct hypertrophy, lingual tonsil, white sponge nevus, racial gingival pigmentation, lingual thyroid, and eruptive cyst. They could be misdiagnosed as oral potential malignant disorders, candidiasis, Human Papilloma Virus (HPV)-related affections, oral autoimmune diseases, or benign and malignant tumors. In some cases, pseudolesions feature in a syndromic panel, for example, fissured tongue in Melkersson–Rosenthal syndrome. It is strictly fundamental for dentists to know and to distinguish oral pseudolesions from pathological conditions, in order to avoid overtreatment. Full article