Study Reviews Technologies, Work Flows in Heavy Oil Reservoir Management

Abstract

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 209328, “Heavy Oil Reservoir Management—Latest Technologies and Work Flows,” by Hakki Aydin, SPE, Middle East Technical University; Nirup Nagabandi, Incendium Technologies; and Cenk Temizel, SPE, Saudi Aramco, et al. The paper has not been peer reviewed. _ Successful heavy oil reservoir management practices are built on analyzing and accurately predicting reservoir behavior over time. Given the complex nature of heavy oil reservoirs, including geomechanical properties and fluid-flow behavior, a need exists to develop a repeatable technique that can account for these complexities within an acceptable margin of accuracy. The objective of the complete paper is to conduct a comprehensive review of recent technologies and work flows developed for heavy oil reservoir management that can be used as a single source of reference for the industry. Introduction Because of its comprehensive nature, much of the complete paper is dedicated to a review of the characteristics of heavy oil reservoirs and their exploitation, including thermal and nonthermal methods and the literature dedicated thereto. This synopsis will concentrate on the authors’ reviews of work flows to manage these reservoirs and field applications of the methodologies they review. Work Flow for Heavy Oil Reservoir Management Reservoir management is a multidisciplinary field involving detailed analysis of geosciences such as reservoir engineering, geological engineering, and petrophysics. Evaluation of geological information and fluid properties helps to understand the distribution of heavy oil in the reservoir. Understanding the characteristics of heavy oil reservoirs is essential for selecting the appropriate enhanced oil recovery (EOR) method. Reservoir-surveillance techniques play a critical role in understanding complex systems. Statistical approaches might be required to handle extensive data sets of production history and petrophysical data. The main goal of the reservoir management team in thermal EOR methods is to optimize parameters in steam-injection projects to maximize recovery rates from heavy oil reservoirs. The important parameters influencing the success of thermal projects include injection rates and pressures, preferential steam paths, well profiles, and reservoir depth. Previous work has presented a work flow for optimizing steamfloods in Oman. The work flow involves a review of production and injection history, petrophysical properties, and geological descriptions. Steam/oil ratio was used as a key performance indicator for steam management; it is defined as barrels of steam injected for 1 bbl of additional oil production. The steam breakthrough was monitored from the wellhead flowing temperature of the producer wells. A sudden increase in wellhead temperature is associated with a steam breakthrough. The permeability map of the reservoir helps to select appropriate injectors for a steamflood. High-permeability wells might lead to fingering, causing less recovery. Vertical conformance is desired to achieve oil sweep with steam. Observation wells are the controlling stations of steamflooding efficiency. It is critical to place the observation wells in heterogeneous reservoirs. Geophysical methods also are applied for surveillance of steam-injection projects. Real-time surveillance plays a critical role in the optimization of heavy oil reservoirs. The authors describe a modeling technique called Production Universe (PU) that enables operators to estimate oil and water production in real time. PU is effective at finding the offending well in case of sudden changes in field-level production. PU provides an automated daily production and deferment report that guides analysts to identify low-efficiency wells for remedial operations.