Проблемы заколонных перетоков в скважинах с боковыми стволами и горизонтальным забоем

The article analyzes the main causes of fluid manifestations that occur in wells with side shafts and horizontal bottom at the stage of construction and operation of wells. It is established that the fluid manifestations are mainly due to the design features of such wells. The presence of overflow and interstratal overflows, in case of untimely detection and liquidation, can lead to emissions, accidents and large–scale environmental disasters. The cause of most complications at the stages of construction and operation of wells is the hydraulic connection of the drilled fluid–saturated formations with the wellbore, which accompanies all subsequent periods of well operation. To solve this problem, it is necessary to carry out repair and insulation works to eliminate overflow flows in wells with horizontal sections using blocking fluids for temporary insulation of the perforated part of the production string. Technological solutions for the elimination of intercolumn flows by pumping blocking tamponing compositions in the intervals of flow of liquids or gases, the installation of cut–off bridges to protect the productive layers from the cement material; carrying out insulation work through the upper part of the perforation zone. The authors propose the current directions of development of existing insulation technologies, taking into account the peculiarities of work in horizontal wells, in the construction of which use non–cemented shank–filters using physico–chemical and mechanical solutions. The selected technology and materials should ensure the filling of the entire porous medium and channels in the well and downhole section of rocks, as well as the optimal structure of the composition in a technologically acceptable time.

HOMOGENEOUS LOW-CRESTED STRUCTURES FOR BEACH PROTECTION IN CORAL REEF AREAS

In many countries, the health of the marine ecosystems and the sun-sand-sea tourism depend on the coral reefs, which have been retreating around the world during the last decades. Homogeneous Low-Crested Structures (HLCS), made of large rocks or pre-cast concrete units, can be placed to mimic the functions of beach protection and eventually serve as a refuge for species. HLCS is a type of multi-purpose green infrastructure which is functionally similar to conventional low-crested structures but have higher porosity and are more easily dismantled for re-use. Contrary to conventional low-crested structures, the functionality of HLCS protecting beaches depends on the selected placement grid; this paper describes physical and numerical placement tests on horizontal bottom used to characterize the layers coefficients of Cubipod HLCS. The Bullet Physic Engine (BPE) numerical model used in the gaming industry, which is based on the rigid body method, is calibrated using the physical placement tests. The layer coefficients of Cubipod HLCS measured in the physical placement tests were similar to those obtained with the BPE numerical model, which could be used to optimize placement grids of HLCS on specific sea bottom conditions. Finally, the influence of the placement grid of Cubipod HLCS on the structure height, crest freeboard and wave transmission is analyzed.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/5bi-jpuJYcQ

New Compound Open Channel Section with Polynomial Sides: Improving Cost and Aesthetics

Previous research on compound trapezoidal cross sections has mainly focused on improving the prediction of the discharge (flow rate) because of its inherent challenges. This paper focuses on two other important aspects: Section shape and optimal construction cost. First, the paper proposes a new compound section with third-degree polynomial sides of main channel with horizontal bottom (HB) that allows its top corners to be smooth, called herein compound polynomial section. The special cases of this versatile section include the simple polynomial section, polygonal section, trapezoidal-rectangular section, two-segment linear-side section, and parabolic bottom-trapezoidal section. The simple polynomial section, which is the bank-full part of the compound polynomial section, can further produce parabolic (with or without HB), trapezoidal, rectangular, and triangular sections. Second, an optimization model that minimizes construction cost (excavation and lining) of the compound (or simple) polynomial section is developed. The model includes discharge and physical constraints. Theoretical and empirical methods of discharge prediction were used in the model. The results show that the simple polynomial section was more economical than the popular parabolic section by up to 8.6% when the side slopes were restricted. The new polynomial-based sections not only reduced construction cost, but also improved maintenance and aesthetics. As such, the new sections should be of interest to researchers and practitioners in hydraulic engineering.

On the application of the Green‒Nagdi equations for the simulation of wave flows with undular bores

The basic conservation laws in the Green–Nagdi model of shallow-water theory are derived from the two-dimensional integral conservation laws of mass and the total momentum describing the plane-parallel flow in an ideal incompressible fluid above a horizontal bottom. This conclusion is based on the concept of a local hydrostatic approximation, which generalizes the concept of the long-wavelength approximation and is used for analyzing the applicability of the Green–Nagdi equations in modeling the wave flows with undular bores.