Abstract
The study that we conducted into the process of transportation of a gas-condensate mixture from a well bottom to the separation production plant has revealed the features of isothermal and non-isothermal flow. It was proved that during non-isothermal flow, hydraulic losses in the product pipeline are significantly affected by throttle effect and energy accommodation effect. The influence of velocity and volumetric flow rate of the gas-liquid mixtures on hydraulic resistance and pressure drop on a section of product pipeline, taking into consideration non-isothermal flow was analyzed. It was found that the assessment of hydraulic resistance and pressure drop in the proposed dependences converges with standardized ones by 95 %. The result was obtained based on the developed system of equations of the mathematical model for non-isothermal non-stationary one-dimensional motion of the gas-liquid mixture of hydrocarbons in the pipeline. The proposed system beneficially differs from the known ones by the fact that it takes into consideration the inner convective heat exchange, estimated by the combined effect of Joule-Thomson.A distinctive feature of the improved procedure for calculation was the introduction of temperature correction and accommodation coefficient in the calculation of hydraulic resistance of a pipeline as a system with distributed parameters. Due to this, it became possible to improve the procedure for the calculation of non-isothermal transportation of a homogeneous gas-condensate mixture. Based on the analysis of calculation curves by the known procedures (formulas of Thomas Colebrooke, Leibenson and VNIIgas) for isothermal and non-isothermal processes and the proposed procedure, rational areas of their applications were shown. All calculations were performed at the velocity of a gas-liquid flow within the range 0–50 m/s, pipe roughness of 0.01–0.05 mm and their diameter of 100–300 mm, the data from actual production pipelines of Novotroitsk oil-gas condensate field were used. Comparison of the theoretical and industrial experiments showed sufficient for engineering practice accuracy of calculation of pressure drop on the stretches of oil and gas lead lines and allowed recommending the developed analytical dependences for the introduction in industrial engineering.
Highlights
Engineering practice in the oil and gas industry solves the problem of the evaluation of hydraulic resistance of a pipeline for transportation of hydrocarbons
The difference of calculation data for pressure losses along the pipeline by the standard procedure and the proposed formulas are within an engineering error
Analysis of the curves obtained for the developed model and corresponding calculation formulas shows:
Summary
Engineering practice in the oil and gas industry solves the problem of the evaluation of hydraulic resistance of a pipeline for transportation of hydrocarbons. For their mixture, this problem is greatly complicated by different state of hydrocarbons, constantly changing geometry of their distribution in the pipeline cavity, different ratios of specific volumes of transported substances. In oil and gas extraction, depending on hydraulic losses, diameters of vertical oil well tubing (OWT) of horizontal well lead lines and inter-field flow lines [1,2,3] are selected. At mainline multi-pipe transportation of oil and gas, it is appropriate to change thermo-hydraulic operation modes in the networks, transform the topology and schemes of transportation [4,5,6,7]
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