The application of risk-based methods to multilateral well design
Lucien Jason Nguyen A , Paul F. Pickering B and Zachary M. Aman AA The University of Western Australia
B Woodside Energy
The APPEA Journal 56(1) 427-434 https://doi.org/10.1071/AJ15031
Published: 2016
Abstract
Horizontal and multilateral oil and gas wells are used to maximise hydrocarbon recovery while reducing the required well count and associated costs. Presently, lateral lengths are designed using semi-quantitative methods. Guided by a desire to minimise the risk of poor well deliverability, the tendency is to design producing lengths longer than required, with the rationale that the well connects with sufficient hydrocarbon bearing reservoir to provide good deliverability. Drilling long producing lengths, however, is expensive and generates a higher risk of drilling and lifecycle (intervention and workover) problems. Furthermore, attempting to increase deliverability by extending the producing length encounters the law of diminishing returns as the flow becomes constrained by tubing friction loss.
This paper seeks to quantify the optimal length for a horizontal well for a given range of reservoir conditions through multiphase fluid modelling and stochastic analysis. A discretised horizontal well model was created, which shows how changing the well length transforms the probability density function of the production rate for the well. A parametric case study was conducted, which demonstrates the evolution of the optimal well length and production rate with parameters including well diameter, fluid viscosity and well flowing bottomhole pressure. A simplified economic analysis illustrates the incremental change in discounted cash flow and quantified risk from drilling a longer well. The model also considered the influence of inflow control devices (ICDs) to adjust the inflow to match permeability and even-out inflows along the producing length, thus reducing the risk of gas and water coning, and improving hydrocarbon recovery.
Lucien J. Nguyen is a graduate from the University of Western Australia (UWA), with Master of Mechanical Engineering and Bachelor of Commerce (Management) degrees. His CEED thesis with Woodside Energy investigated the optimal length of horizontal and multilateral wells, and the optimal configuration of inflow control devices (ICDs) to maximise productivity and hydrocarbon recovery. He has interned at Shell, ExxonMobil, Deloitte, KPMG, Ernst & Young, Main Roads, and Concept CS. Lucien’s roles have included UWA representative for the Society for Underwater Technology, and co-founder and co-president of The Institution of Mechanical Engineers UWA Chapter. lucien@jason-nguyen.com.au |
Paul F. Pickering is a Principal Flow Assurance Engineer at Woodside Energy Ltd where he works in the design of oil and gas production systems. His career has been spent largely working in the area of multiphase flow and modelling of fluid flow systems, most notably with the foundation of FEESA Ltd and the invention of the Maximus Integrated Production Modelling software. He holds MEng (1990) and PhD (1994) degrees in chemical engineering from Imperial College, London, with a research focus on transient instabilities in multiphase flows. Paul.Pickering@woodside.com.au |
Zachary M. Aman is an Associate Professor of Chemical Engineering at the University of Western Australia. His x focuses on the management and prevention of gas hydrate and asphaltene blockages in subsea oil and gas pipelines, as well as the transport of oil through the water column during deepwater blowout. He holds a BSc degree (2009) and a PhD (2012) in chemical engineering from the Colorado School of Mines, with a research focus on the interfacial phenomena of cyclopentane hydrate at the Center for Hydrate Research. Member: SPE, ACS, AIChE, and IChemE. Zachary.Aman@uwa.edu.au |
