NETWORK MODELING AND TRACKING OF LIQUID PREFERENTIAL ROUTES IN NATURAL GAS PIPELINE SYSTEMS

Open Access
Author:
Essenfeld, David
Graduate Program:
Petroleum and Natural Gas Engineering
Degree:
Master of Engineering
Document Type:
Master Thesis
Date of Defense:
March 04, 2010
Committee Members:
  • Dr Luis Ayala, Thesis Advisor
  • Luis Ayala, Thesis Advisor
Keywords:
  • Essenfeld
  • Ayala
  • Panhandle
  • Beggs and Brill
  • Wetmouth
  • Gathering System
  • Natural gas
  • Pipelines
  • Multiphase flow
  • ROute selectivity
  • liquid preferential route
  • tee junction
Abstract:
ABSTRACT Liquids, water in particular, are responsible for additional pressure losses in natural gas surface production systems. For the case of natural gas stripper well facilities, the optimization of these surface fluid transportation operations is vital for a successful business. This research work is aimed at developing and testing an analytical tool able to track and map the preferential route of water in natural gas network systems so that the operator can make better decisions regarding system optimization, resulting in a more economically viable operation. The accurate mapping of the pressure, velocities of the phases and fluid re-distribution inside the network is critical, since it can reduce additional compression costs caused by the liquid phase, help to make decisions regarding water removal from the network, and also affect the design and location of surface production and separation equipment. This study was undertaken in stages, starting with the development of a one-dimensional, steady state tool for modeling the flow of a single phase fluid (gas) in pipes. This model was then expanded to account for the additional pressure drop due to the appearance of multiphase flow conditions in the system by employing the Beggs and Brill model (1999). In the final stage, tee junction sequences were incorporated to create network-wide prediction capabilities. The products of each of the stages were validated and crosschecked independently and as a group with commercial simulators and field data. The present work shows that the proposed model is capable of handling two-phase splits at tee junctions, especially for the common case of uneven splits—which commercially available network simulators do not model and cannot capture. As a result, the proposed multiphase network model is able to tackle realistic field scenarios where flowing phases do take their own preferential paths-resulting in sections of the network having dry and wet flow regions. The proposed model thus allows the user to effectively trace the liquid‘s path and plan to undertake the adequate corrective operational measures to maintain system capacity and minimize compression requirements, thereby improving the performance of the entire network.