Summary To prevent or minimize problems associated with water coning in horizontal oil producers, inflow control devices (ICDs) are installed along the wellbore to better equalize the toe-to-heel flux. Nozzle-based ICDs are popular because they are easy to model accurately, virtually viscosity independent, and easy to install at the wellsite with many settings. Nozzles can be installed either in the wall of the base-pipe (radial orientation) or in the annulus between the base-pipe and housing (axial orientation). The advantages of the former are smaller maximum-running outer diameter (OD) and no need for a leak-tight, pressure-rated housing. One disadvantage is the high exit velocity that raises concern of erosion or erosion-corrosion of the base-pipe. To overcome this disadvantage, a new nozzle has been developed with a novel geometry that reduces the exit velocity approximately tenfold compared with a conventional nozzle for the same pressure drop and flow rate. Computational fluid dynamics (CFD) was used to first fine tune the design to meet strict erosion-corrosion prevention requirements on the wall shear-stress downstream of the nozzle for both production and (acid) injection directions, and then to develop flow-performance curves for four different nozzle “sizes” that vary in their choking ability, thereby allowing many different settings per joint at the wellsite. Full-scale prototype manufacturing and flow-loop testing were then performed to validate the CFD flow-performance predictions and to demonstrate mechanical integrity and erosion resistance for high-rate production and injection. The results, as presented herein, demonstrate a robust and commercially viable ICD design that has predictable flow performance using CFD, minimizes erosion and erosion-corrosion in either direction, minimizes running OD, simplifies the housing design, and allows easy installation at the wellsite with 34 settings per joint. Also discussed are two new advantages over other ICDs that were not anticipated in the original development.
To prevent or minimize problems associated with water coning in horizontal oil producers, inflow control devices (ICDs) are installed along the wellbore to better equalize the toe-to-heel flux. Nozzle-based ICDs are popular because they are: 1) easy to model accurately, 2) virtually viscosity independent, and 3) easy to install at the wellsite with many unique settings. Nozzles can be installed either in the wall of the base pipe (radial orientation) or in the annulus between the base pipe and housing (axial orientation). The advantages of the former are: 1) smaller max running OD, and 2) no need for a leak-tight, pressure-rated housing. One disadvantage is the high exit velocity that raises concern of erosion or erosion-corrosion of the basepipe. To overcome this disadvantage, a new nozzle had been developed with a novel geometry that reduces the exit velocity about ten-fold compared to a conventional nozzle for the same pressure drop and flow rate. Computational fluid dynamics (CFD) was used to first fine tune the design to meet strict erosion-corrosion prevention requirements on the wall shear stress downstream of the nozzle for both production and (acid) injection directions, and then to develop flow performance curves for four different nozzles "sizes" that vary in their choking ability, thereby allowing many unique settings per joint at the wellsite. Full scale prototype manufacturing and flow loop testing were then performed to validate the CFD flow performance predictions and to demonstrate mechanical integrity and erosion resistance for high rate production and injection. The results, as presented herein, demonstrate a robust and commercially viable ICD design that: 1) has predictable flow performance using CFD, 2) minimizes erosion and erosion-corrosion in either direction, 3) minimizes running OD, 4) simplifies the housing design, and 5) allows easy installation at the wellsite with 34 unique settings per joint. Also discussed are two new advantages over other ICDs that were not anticipated in the original development.
When a pipeline requires a repair, a pressure-containing steel sleeve or an emergency repair fitting is often fillet welded to the in-service pipe to return the pipeline to normal service conditions. During welding, the flowing product rapidly quenches the fillet weld, promoting the formation of high hardness and low ductility microstructures in the heat-affected zone. The rapid cooling rates also limit the mobility of diffusible hydrogen introduced from the welding electrodes. The hydrogen can be trapped in the weld metal and heat-affected zone and concentrated in specific locations throughout the weld based on the welding deposition sequence. Fillet welds also contain inherent locations of geometric stress concentration at the weld toes and root locations. The elevated hydrogen concentration in the in-service weld, combined with the geometrical stress concentrations at the location of crack-susceptible microstructures, can increase the likelihood of forming a hydrogen-induced crack. Delayed non-destructive examination (NDE) is often employed to wait a sufficient time for any cracks to form so they can be detected. To reduce hydrogen concentration at the locations of stress concentration and NDE delay times, post-heating can be applied to the in-service weld. Elevating the temperature within the weld can enable hydrogen diffusion and reducing the cracking propensity. The rapid heat removal due to flowing product requires post-heating techniques with high energy outputs that will not overheat the steel surfaces. Electromagnetic induced current (induction heating) methods can produce sufficient thermal energy in the electrically conductive steel pipe and sleeve. Coupled numerical finite element analysis (FEA) models were utilized to simulate various induction cable arrangements and thermal convection coefficients, representative of various pipeline products. The analysis of the induction heating arrangements for the studied thermal convection coefficient was conducted to achieve a minimum temperature of 120 °C in the fillet weld root and toes to enable sufficient thermal driving force for hydrogen diffusion while ensuring the pipe and sleeve surface temperature does not exceed 200 °C. An optimal induction heating procedure was found to which could achieve the target temperatures within a reasonable heating time such that NDE delay times of in-service welds can be reduced by 5–6 times.
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