The Nord Stream 1 & 2 Subsea Pipeline Projects are a tremendous feat of engineering. In a previous Tip of the Month, we discussed the technical aspects of the Phase Envelope, Hydraulics, Diameter selection, Pipe wall thickness, pressure gradient profile, and flowrate for these multiple parallel pipelines. This Tip of the Month will present some context and comparison of the magnitude of some of these numbers. [Keep reading]
Se han puesto en marcha gasoductos con capacidad del transporte del CO2, y el gas natural en su fase densa. Debido a la alta densidad de este resulta en gasoductos de menor diámetro representando ahorros sustanciales. El transporte de fase densa igual asegura la eliminación del liquido en la tubería para los sistemas de producción del gas natural. La aplicación de la fase densa de los hidrocarburos fue discutido brevemente en el Previo del Mes de Agosto 2012. Hemos analizado el transporte del gas natural en su fase densa y comparado estos resultados con el caso de la transmisión del citado gas aplicando la opción de dos fases (gas-liquido) Nuestras investigaciones sobresaltaron algunas ventajas así como las desventajas relacionadas cn el transporte del ga en su fase densa. En este PDM (TOTM), presentaremos un resumen, incluyendo varias facetas únicas del citado transporte del gas natural en el gasoducto Nord Stream 1. [Keep reading]
Pipelines have been built to transport CO2 and natural gas in the dense phase region due to its higher density which results in a smaller pipeline diameter resulting in significant capital cost savings. Dense phase transport also provides the added benefit of no liquid formation in the pipeline for produced natural gas gathering systems. The application of dense phase in the oil and gas industry was discussed briefly in the August 2012 TOTM. We have studied transportation of natural gas in the dense phase region and compared the results with the case of transporting the same gas using a two phase (gas-liquid) option. Our study highlighted some of the advantages as well disadvantages transporting natural gas in the dense phase. In this TOTM, we will present an overview, including some of the unique features, of the dense phase transportation of natural gas by the Nord Stream 1 pipeline. [Keep reading]
Part 3 of the Overview of Gas Lift series has procedures for identifying, selecting, and optimizing technical as well as field operations for a gas lift well. Section IIIA reviews the gas lift well candidate related to gas content in the reservoir fluid and a choice of gas lift or pumping. Section IIIB discusses the well completion related to dimensional and clearance considerations and gas lift facility requirements. Section IIIC has guides for kicking off a well and avoiding erosion cutting of the unloading valves. Section IIID provides the procedure to optimize the well once it has kicked off and is operating in the production system. [Keep reading]
In the Part 1 of this Series on Gas Lift History and Basic Well Parameters, an attempt was made to bring into focus the primary “state of affairs” of Gas Lift operations in the USA. Part 2 will discuss basic Gas Lift well casing and tubing components, and their operational function, as well as Choke Flow relationships in Gas Lift wells. In the First Section II.A, Energy and Mass Balance relationships will be used to compute flowing pressure gradients, (dP/dL) (psi/ft) for injected casing gas ((dP/dL)g), and for further documents addressing this subject, multiphase flow in the tubing ((dP/dL)mp). Section II.B will address gas injected at surface into the annular space between production casing and tubing. The injection gas travels down the annular space on its way to either a “kickoff “gas-lift” valve located in a tubing MANDREL with an Injection Pressure Operated gas lift valve (IPO), or to the bottom Orifice GLV. Calculations will be performed to determine injected gas annular flow vs. pressure loss related to the 9 5/8” casing and either the 2 3/8”, or 2 7/8” production tubing. The flow is then considered in the annular space between the 7” liner and either the 2 3/8’’, or 2 7/8’’ production tubing. Casing gas flow does not encounter the 5” liner. Physical dimensions for these selections will be addressed. Section II.C presents the basic, single phase gas flow performance characterization related to CHOKE FLOW in the Gas Lift Valve. Once a valve has been fitted with a choke (orifice) size, the flow performance of a choke will follow the mass, and energy balance relationships related to isentropic gas expansion. This flowing condition for the choke MUST be selected in its transitional, sub-critical flow region so that additional changes to injection gas flowrates may be made if called for. It is essential to design the final Orifice GLV so that operation near, or in the Critical Regime (Sonic Flow) is avoided. A numerical example will be presented to illustrate the direct application Casing / Liner Gas injection data with the corresponding IPR Tubing Gas Lift Valve with installed CHOKE dimensions. [Keep reading]
In December 2021 tip of the month (TOTM), we presented two simple empirical correlations for estimating pure liquids surface tensions of the paraffins methane through n-octane. The two correlations express the surface tension as a function of the reduced temperature and molecular weight with only two (first correlation) and four (second correlation) fitted parameters. These correlations and the smoothed experimental data were used to generate three figures for methane through n-octane and a few heavy ends with known molecular weights. In this follow-up TOTM, an estimation method for surface tension for the paraffin liquid mixtures in equilibrium with natural gas with a fixed feed composition will be presented. Using the SRK-EOS of ProMax five charts were generated to estimate the hydrocarbon liquid mixtures surface tensions, σ, as a function of temperature and pressure at a specified inlet feed gas relative density in the range of 0.6 to 0.8. The feed gas composition was flashed to varying temperatures and pressures within the two-phase region of the feed gas envelope to generate the liquid and vapor phases. The resulting liquid surface tension estimates were then plotted. In addition, the accuracy of a semi empirical approach based on the Macleod basic relationship to estimate σ was evaluated and summarized against the surface tension values calculated by ProMax. [Keep reading]
