A Pressure Traverse Algorithm for Multilateral Oil and Gas Wells
Bruno Ramon Batista Fernandes1; Francisco Marcondes2; Kamy Sepehrnoori1
1 Center for Petroleum and Geosystems Engineering, The University of Texas at Austin; 2 Federal University of Ceará
doi:10.20906/CPS/CILAMCE2017-0449
Resumo
Pressure traverse algorithms are important to determine the pressure distribution and rates along oil and gas wells, allowing the coupling of surface and subsurface parameters such as wellhead and bottom hole pressures. Pressure traverse algorithms assume the well is divided into several segments and these algorithms are usually derived assuming no fluid accumulation along well through an energy balance. The fluid flow pattern (i.e., bubble, slug, mist, etc.) are incorporated into the calculations of the pressure drop due to friction, fluid slippage, and average total velocity. Many algorithms for the pressure traverse are available in the literature, but just a few are devoted to multilateral wells. Adding branches to a well increase the complexity of the problem as the pressure and rate distribution in the system are coupled. In this paper, a recursive pressure traverse algorithm for multilateral wells is presented. We assume that the well can have vertical, curved, and or horizontal sections. The pressure drop in horizontal section is neglected. Two phase flow (oil and gas) is considered with four flow patterns: bubble flow, slug flow, transition flow, and mist flow. The fluid properties are modeled using the Black-Oil model and the wellbore is coupled to a basic reservoir through a productivity index and each lateral is assumed to penetrate different producing formation layers. The results are presented in terms of pressure distribution, production rates for several well head pressures, slippage velocity, among others. The results are validated against no flow wellbore (hydrostatic pressure) model and single lateral wells. The algorithm was able to converge for an arbitrary number of laterals keeping the continuity of the properties along the wellbore.
Palavras-chave: Pressure Traverse; Multilateral Wells; Multiphase Flow