Annular pressure

The perforation wash tool is retrieved and the packer run in the hole with a work string, set at the desired depth and tested. An annular pressure test of 1,000 psi is usually sufficient. The packer is run with or without a tail pipe, depending on the operation to be performed. If cement is to be spotted in front of the perforations, a tail pipe that covers the length of the zone plus 10 to 15 ft must be run with the packer. 

A series of tap connections in an annular pressure ring gives a mean value for the pressure at point 1 in the approach section and also at point 2 in the throat. Although Venturi meters are relatively expensive and tend to be bulky, they can meter up to 60 per cent more flow than orifice plates for the same inside pipe diameter and differential pressure [Foust et al. (1964)]. The coefficient of discharge Cd for a Venturi meter is in the region of 0.98. Venturies are more suitable than orifice plates for metering liquids containing solids. 

The pressure difference between the lower cylindrical compartment and the lower annular compartment was measured. To make sure that the flow through the sample material had only a through-plane component (z-direc-tion), the back-pressure valve was adjusted until the lower annular pressure was equal to the pressure experienced by the lower cylindrical compartment. The temperatures of the inlet and outlet lines, as well as the flow rate of the gas leaving the lower cylindrical compartment, were monitored. A wide... 

Huddling chamber An annular pressure/boosting chamber in an SRV located above the seat area for the purpose of generating a rapid opening (Figure 3.12). 

It should be recalled that, in annular pressure flows, as in all pressure flows, an error is introduced by using the Power Law model fluid because of inaccuracies in the low shear rate regions. Moreover, the assumption of isothermicity also introduces errors and can lead to an overestimation of P0 — PL. 

For isothermal annular pressure flow of an incompressible Power Law fluid, Fredrickson and Bird (97) have calculated the following relationship between Q and AP... 

The annular pressure drop for a Bingham fluid is obtained from... 

Marken et al. (110) have given a detailed account of the factors affecting annular pressure losses, including the effects of rotational flow in the annulus. It might be expected that rotational flow in the annulus would decrease the frictional pressure losses as the increased shear rate would lower the viscosity. However, Marken et al. observed an increase in frictional pressure due to the formation of Taylor vortices. McCann et al. (J07) have observed increases in the frictional pressures in slimhole annuli due to annular rotation of the drilling fluid. 

Plot shows total annular pressure and the hydrostatic component... 

Annular Pressure Assessment for Supercritical Carbon Dioxide Injectors Designed for Carbon Capture AND Sequestration... 

Leakage at a number of wellbore depths has been thoroughly evaluated, including the top, the middle and the bottom of the aimulus. To further improve our understanding of the annular pressure behavior, impacts of CO2 injection temperature, as well as baekflush at different CO2 injection stages have also been investigated. 

For heat transfer assessment, the CO2 injection at a various temperature has been evaluated with comprehensive OLGA dynamic simulation. Similarly, baekflush operation at a number of in-situ formation fluid temperatures (to mimic reservoir eonditions at different stages of CO2 injection project) has also been investigated to better understand the annular pressure behaviors. 

Annular Pressure Assessment for Supereritical Carbon Dioxide. .. 77... 

The leakage would lead to the full annular pressure inerease in around 0.05 hours or 3 minutes (Figure 2). 

Figure 2. Annular Pressure Change during a Tubing Leakage.

Table 1. Annular Pressure before and after Tubing Leak during CO2 Injection...

The annular pressure increase has been foimd to be well correlated to the leakage depth (the correlation coefficient is as high as 0.9994, in a very close proximity of unity) ... 

Figure 4. Variation of Annular Pressure Change with Leakage Depth.

Eq. (1) can be applied to estimate the CO2 tubing leakage based on the amount of the annular pressure increase ... 

From a real-time monitoring of the annular pressure in a CO2 injection well, the APa can be calculated and then used to determine the carbon dioxide leakage depth by means of Eq. (2). 

Similar to a routine CO2 injection, in case of tubing leakage during well shut-in, the annular pressure has also been found to increase, although at shghtly smaller pace (Table 2 and Figme 5) than those predicted for a flowing CO2 injection well. 

Once again, a very good correlation can be fonnd between the annular pressure increase and the depth of the leakage point ... 

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