Comprehensive Experiments and Modelling Reduces Uncertainties in Liquid Management for the Tanzania Gas Project

摘要

The Tanzania Gas Project aims to exploit reserves located offshore from Tanzania in East Africa. Thernproject faces challenges in the management of liquid content due to deep waters, rough seabed terrain, longrntransport lines to shore, relatively steep inclinations, and very dry reservoir fluids. The narrow operationalrnenvelope associated with the water depth underlines the importance of accurate flow simulations forrndesign and production. In addition, the low liquid loading conditions are expected to result in substantialrnliquid accumulation in the upwardly inclined sections of the pipeline for low production rates. A largescalernexperimental campaign was launched to reduce the uncertainty in the field development. A novelrnexperimental "screening technique", allowed for the sampling of an unprecedented number of flow raterncombinations corresponding to the onset of liquid accumulation. Diameter scaling was addressed byrnconducting similar experiments in 8- and 12-in. pipes. Froude number similarity was utilized for scaleuprnand to assess model predictions for field conditions. The data confirmed That the flow model capturesrnthe correct physics, and allowed for fine tuning. The updated model was applied in an uncertaintyrnanalysis for the Tanzania field, based on a large number of combinations of key input and flow modelrnparameters, sampled from estimated uncertainty distributions. Simulation results for gas production rate,rnminimum turndown point, etc. were determined as probability distributions. The effort to quantify andrnreduce uncertainty has been very successful. Engagement of the operating company with experimentalrnresearchers, model developers, and software suppliers greatly increased the understanding of the physicsrnand diameter scaling of low liquid loading flows, significantly reducing the uncertainty for gas condensaternfield developments.