Effect analysis of non-condensable gases on superheated steam flow in vertical single-tubing steam injection pipes based on the real gas equation of state and the transient heat transfer model in formation

J Petrol Explor Prod Technol

et al. 2018

Self Cite

It is crucial to precisely estimate the water transport behaviors in shale formation. However, the present study on this subject is quite limited. A comprehensive literature review is conducted and some improvements are proposed. In this paper, an improved model is proposed to investigate the flow of water in nanopores of shale formation. First, a quadratic equation is proposed to build the relationship between water viscosity and contact angle. Then, the effect of critical thickness on water transport behaviors is discussed. Results show that: (a) the flow enhancement is smaller than 1 when the contact angle is smaller than 100° due to energy barrier induced by strong hydrophilicity of the nanopore wall; (b) the flow enhancement becomes infinite when the contact angle is approaching 180°; and (c) the flow enhancement increases with decreasing of critical thickness, especially for hydrophilic nanopores (the contact angle is smaller than 120°) and nanopores with a relatively small diameter (smaller than 50 nm).

Section: Transport Modelmentioning

confidence: 99%

Effect of critical thickness on nanoconfined water fluidity: review, communication, and inspiration

J Petrol Explor Prod Technol

et al. 2018

Self Cite

“…1. Besides, some basic assumptions are made in order to establish the model, as shown below (Sun et al 2017j):…”

Section: General Assumptionsmentioning

confidence: 99%

A brief communication on the effect of seawater on water flow in offshore wells at supercritical state

J Petrol Explor Prod Technol

et al. 2018

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At present, the study of supercritical water (SCW) flow in wellbores is at the starting stage. In this paper, a simple but useful model is developed to study the effect of seawater on the thermophysical properties of SCW in offshore vertical wellbores. Firstly, based on the momentum and energy balance equations, a flow model describing SCW flow in a tube is established. Then, coupled with transient heat transfer model in seawater and formation, and thermophysical parameters of SCW, a comprehensive mathematical model is established. In order to solve the model, the governing equations are expressed in the form of difference equations. The straight forward numerical method is adopted to solve the model from wellhead to well-bottom. In the process of solving, iterative technique is used to control the calculation accuracy. Finally, type curves of SCW flow in offshore wellbores and sensitivity analysis are discussed. Results show that (a) the flow of seawater results in a rapid decline in the temperature/enthalpy of SCW in wellbores. (b) Heat loss is the dominant factor of physical parameter distribution in wellbores when the injection rate is relatively small. (c) Heat loss has an obvious influence on temperature drop when SCW is sparse in volume. (d) The SCW pressure decreases with increasing of injection temperature. KeywordsHeavy oil recovery • Wellbore modeling • Supercritical water • Effect of seawater • Heat loss rate • Injection parameters List of symbols w SCW The mass flow rate of SCW in offshore wells (kg/s) r ai The inner radius of the inner tubing (m) SCW The density of SCW (kg/m 3 ) v SCW The flow velocity of SHS (m/s) zThe well depth (m) Q SCW The heat transfer rate from SCW to seawater/formation (J/s) h SCW The specific enthalpy of SCW (J/kg) gThe gravitational acceleration (m/s 2 ) The well angle from vertical (rad) fThe shear force in the vertical wellbores (N)

“…Superheated steam is obtained by continually heating saturated steam until its temperature begins to increase when pressure is kept unchanged. The temperature difference between SHS and saturated steam under the same pressure is defined as the superheat degree . Superheated steam has been proved to be effective in improving formation permeability, hydrothermal cracking efficiency, increasing heated radius, and so forth .…”

Section: Introductionmentioning

confidence: 99%

Exploitation of heavy oil by supercritical CO₂: Effect analysis of supercritical CO₂ on H₂O at superheated state in integral joint tubing and annuli

et al. 2018

Greenhouse Gases

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The injection of supercritical CO2 coupled with superheated steam (SHS) for heavy oil recovery can improve development efficiency. In order to help oil fields to improve the efficiency of CO2 and SHS utilization we must predict the thermophysical properties at well bottom. Based on the mass, energy, and momentum conservation equations, a non‐isothermal pipe‐flow model is established considering heat exchange between the integral joint tubing (IJT) and annuli. Coupled with the transient thermal conduction model in stratum and the S‐R‐K real gas model, a comprehensive model is established for the mixture flow in concentric dual‐tubing wells (CDTW). The model is solved by a numerical method and an iteration technique. The results show that: (a) the accuracy of the temperature profile calculation has been greatly improved compared with the previous model; (b) the heat‐carrying capacity per unit mass of the mixture and heating efficiency decrease with increasing supercritical CO2 content; (c) when a temperature difference exists between the IJT and annuli, a rapid flow of thermal energy exists inside the CDTW, which causes a significant temperature change near the wellbore, but the influence of temperature change on pressure profiles is negligible. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.