Estimation of the value of leaks through a through defect of the pipeline when using in-pipe repair elements

The loss of hydrocarbons when using in-pipe repair elements is determined by the nature of the fluid flow in the gap between the pipe and the repair sleeve. An accurate analytical calculation of the flow parameters for a real sleeve, taking into account its length, the asymmetry of the defect and other design features, is very difficult. In this article, the problem of accurate calculation of the radial flow of a viscous incompressible fluid in a thin layer between two annular plates simulating a circular region with a center coincide with a pipeline defect is solved. The area consists of two circles formed by the pipeline wall with a through defect and the surface of the internal repair element. The results obtained will allow us for accurate calculations in the area adjacent to the defect of the pipe and approximate calculations for the whole repair element.

Catalog of Wide Binary, Trinary and Quaternary Candidates from the Gaia Data Release 2 (Region ∣b∣ > 25°)

The occurrence of multiple stars, dominantly binaries, is studied using the Gaia-ESA DR2 catalog. We apply the optimized statistical method that we previously developed for the analysis of 2D patterns. The field of stars is divided into a mosaic of small pieces that represent a statistical set for analysis. Specifically, data input is represented by a grid of circles (events) with radius 0.°02 covering the sky in the field of galactic latitude ∣b∣ > 25°. The criteria for selecting candidates for multiple stars are based on two parameters: angular separation and collinearity of proper motion. Radial separation, due to limited accuracy, is used only as a weaker supplementary constraint. Due attention is paid to the accurate calculation of the background, which is a necessary input for evaluating the quality of the candidates. Our selection algorithm generates the catalog of candidates: 900,842 binaries, 5282 trinaries, and 30 quaternaries.

Study on the Surge-Swab Pressure considering the Effect of the Cutting Plug in Shale Drilling

Wellbore instability is a frequent problem of shale drilling. Accurate calculation of surge-swab pressures in tripping processes is essential for wellbore pressure management to maintain wellbore stability. However, cutting plugs formed in shale horizontal wells have not been considered in previous surge-swab pressure models. In this paper, a surge-swab pressure model considering the effect of cutting plugs is established for both open pipe string and closed pipe string conditions; In this model, the osmotic pressure of a cutting plug is analyzed. The reduction of cutting plug porosity due to shale hydration expansion and dispersion is considered, ultimately resulting in an impermeable cutting plug. A case study is conducted to analyze swab pressures in a tripping out process. The results show that, in a closed pipe condition, the cutting plug significantly increases the swab pressures below it, which increase with the decrease of cutting plug porosity and the increase of cutting plug length. Under the give condition, the swab pressure at the bottom of the well increases from 3.60 MPa to 8.82 MPa due to the cutting plug, increasing by 244.9%. In an open pipe string condition, the cutting plug affects the flow rate in the pipes and the annulus, resulting in a higher swab pressure above the cutting plug compared to a no-cutting plug annulus. The difference increases with the decrease of the porosity and the increase of the length and the measured depth of the cutting plug. Consequently, the extra surge-swab pressures caused by cutting plugs could result in wellbore pressures out of safety mud density window, whereas are ignored by previous models. The model proposes a more accurate wellbore pressure prediction and guarantees the wellbore stability in shale drilling.

Heat Balance Calculation and Energy Efficiency Analysis for Building Clusters Based on Psychrometric Chart

How to perform accurate calculation of heat balance and quantitative analysis of energy efficiency for building clusters is an urgent problem to be solved to reduce building energy consumption and improve energy utilization efficiency. This article proposes a method for the heat balance calculation and energy efficiency analysis of building clusters based on enthalpy and humidity diagrams and applies it to the energy management of building clusters containing primary return air systems and heating pipe networks. Firstly, the basic structure and energy management principle of building clusters with a primary return air system and a heating pipe network were given, and the heat balance calculation and energy efficiency analysis method based on i-d diagram was proposed to realize the accurate calculation of heat load and the quantification of energy utilization. Secondly, the energy management model of the building cluster with a primary return air system and a heating pipe network was established to efficiently manage the indoor temperature and the heating schedule of ASHP, HN and HI. Finally, the proposed method was validated by calculation examples, and the results showed that the proposed method is beneficial for improving the energy economy and energy efficiency of building clusters.

Cosmology

The main features of the universe and its history, and the application of GR to the universe as a whole are presented. The observed near-isotropy and homogeneity of the universe are described, along with a survey of its history. The Saha equation is applied to the recombination process. Cosmic proper time and comoving coordinates are defined, and the form of the metric (Friedmann-Lemaitre-Robertson-Walker) applicable to such a universe is obtained. The main features of the resulting geometry are discussed at length, with a view to both accurate calculation and sound intuition. Redshift and the cosmic expansion are described from several perspectives. Distance measures (luminosity, angular diameter) are defined and the main elements of the observational cosmic distance ladder are outlined.

The Energy Performance Gap in Swiss residential buildings: a roadmap for improvement

This work deals with the Energy Performance Gap (EPG) in buildings, defined as the difference between actual and theoretical energy consumption. This paper investigates how to close the EPG of existing buildings in Switzerland, by which measures, until when, and at which costs. To address these questions an extensive literature review was conducted combined with qualitative interviews in order to better understand practitioners’ experience and to support the findings from the literature. Several approaches have been found to reduce the EPG. These include both measures to make the building consume as expected and to arrive at a more accurate calculation of the theoretical consumption. We highlight the most relevant solutions for the Swiss context.

Simple and accurate calculation model of viscosity for supercritical CO2

The high-precision calculation method suitable for the viscosity of supercritical CO2 is reported. The modified LBC model, modified DS model and Ehsan empirical formula are selected to calculate viscosity. The error analysis result shows that the average absolute error of the modified DS model is the lowest, which can be applied to the engineering calculation. The LBC model is suitable at 7.5–25MPa and the Ehsan empirical formula has high accuracy at 25–60MPa. Then the viscosity plate is drawn at temperature range of 310–800K and pressure range of 7.5–60MPa, which can be applied in carbon dioxide resources recovery and utilization of technology.

Experimental Study on the Suspension Amount of Invasion Gas in Drilling Fluid with Yield Stress

The gas suspension phenomenon caused by the yield stress of the drilling fluid affects the accurate calculation of wellbore pressure after gas invasion. At present, most studies on the bubble suspension in the yield stress fluid focus on the single-bubble suspension condition and there are few studies on the gas suspension concentration. This paper carried out the GSC (gas suspension concentration) experiment in the simulated drilling fluid, xanthan solution, with different gas invasion methods. The GSC in the drilling fluid under the conditions of diffuse gas invasion and differential pressure gas invasion was simulated by using two methods of stir-depressurization and continuous ventilation. The results showed that when the size of a single bubble satisfied the single-bubble suspension condition, multiple bubbles can be suspended at the same time. The GSC is affected by the average size of the suspended bubbles, the yield stress of the drilling fluid, and the gas invasion modes. For different gas invasion modes, the empirical models of critical GSC related to the dimensionless number Bi are established. Compared with the experimental data, the relative error of the critical GSC in diffuse gas invasion is less than 6% and the relative error of the critical GSC in differential pressure gas invasion is less than 10%. The results of this work can provide guiding significance for accurate calculation of wellbore pressure.