Evaluation of Two-Phase Flow Test Pipeline Configurations for an Offshore Oil Field

Abstract

fu a major oilfield in Saudi Arabia, detailed information on individual well performance is required for operating and planning purposes. Complete design data can only be obtainec through the addition of extensive facilities for periodic testing of all production in the field. Three different test pipeline configurations were considered. Variables included pipe diameter, pipeline length, oil production rate, gas/liquid ratio, and water cut. Lengths up to approximately 10 miles (16.1 km) were considered.Three types of analyses were undertaken. The first analysiS included steady state pressure losses in not only the horizontal segments but also the vertical risers and downcomers at the platforms. The second set of calculations involved transient simulations for both increasing and decreasing flow rates. Finally, slug length and period predictions for both normal and "severe" slugging were performed. Severe slugging occurs only at very low flow rates and negative pipeline inclination angles.Pressure drop calculations based on the Beggs & Brill correlation, with a rough pipe friction factor, showed that 10 in. (25.4 cm) pipelines were adequate for most cases. Transient simulation results indicated that, in general, less than two hours were required to reestablish steady state flow for both increasing and decreasing rates. Normally occurring slugs were found to vary in average length from about 200 to 600 ft (61 to 183m)with a maximum possible slug length of approximately 2500 ft (762 m). Liquid slug lengths for severe slugging varied from about 100 to 800 ft (30.5 to 244 ill depending on the pipeline length and riser height.

Adaptive thresholds‐based leak detection using real‐time transient modeling of two‐phase flows

“…19 The black oil composition was used as fluid and OLGA methodology has been discussed. 10 The geometry used is taken from one of the three configurations from Brill's work 7 as shown in Figure 3. The pipeline length was divided into equal sections and simulations were performed by extracting the data from every section.…”

“…Complete design data can only be gathered by creating major facilities for routine testing of all field production. 7 Three test pipeline configurations were considered for this research with changes in variables such as pipe diameter, pipeline length, oil production rate, gas/liquid ratio, and water cut. Distances up to 16.1 km in length were considered 7 to analyze the performance.…”

“…Brill et al 7 used several combinations of mass flow rate variations in their study, which were modeled using the Taitel, Lee, and Dukler technique. 8 A few attempts utilizing the Scoggins model 9 yielded similar results.…”

“…Additionally, computations were performed using the Taitel, Lee, and Dukler model. 8 The three potential test pipeline topologies that were considered are represented by alternatives A, B, and C by Brill et al 7 in his work.…”

“…doi:10.1002/ prs.12572 APP E NDIX A: Validation of Brill et al 7 work.A.1 | Pipe modelingThe pipe was fixed with a mass rate driven inlet node at one end and a pressure-driven outlet node at the other end with a fixed opened valve in between them. The pipe was then segmented into two sections since the number of sections was not specified in Brill et al7 work. Nominal pipeline diameters of 8 and 10 inches were used for all calculations.…”