Application of Advanced Analysis Techniques for Waterflood Management: A Case Study in a Large Heterogeneous Carbonate Reservoir

Abstract

Literature is replete with numerous techniques for waterflood analysis developed over the last four decades. Most of these techniques are in the form of simple diagnostic plots based on available production/injection and pressure data routinely gathered in the field. This paper illustrates a systematic methodology that integrates various diagnostic plots at field, sector, pattern and well levels. It shows the interaction between these levels and how the integration of different diagnostic techniques are key to better understand the dynamics of waterflood performance and for identification of performance improvement opportunities. The techniques presented in this paper were applied to evaluate the waterflood performance & efficiency, to identify anomalous performances, to detect production and injection problems, to establish water production mechanism, and to assess impact of reservoir heterogeneities in a giant carbonate reservoir located in the Arabian Gulf. The subject reservoir has been producing under a large scale pattern waterflood for over 30 years. The construction and uses of various diagnostic plots for quantitative assessment of the waterflood performance are presented in this paper. As a first step, the historical performance plots are used to evaluate the maturity of water production and to provide an indication of the sweep and recovery efficiency. The voidage replacement ratio (VRR) when integrated with historical pressure profiles and material balance plots provides critical information on the reservoir pressurization process. The water breakthrough time and the WOR trends are then used in evaluating the water production mechanism and in assessing the reservoir heterogeneity. Production logs (PLT, WFL, PNC, CHFR and RST) provide key information for monitoring and evaluating vertical and areal sweep in the reservoir. Hall plots provide information regarding the injection well performance and related dynamics. The approach presented above led to significant enhancement in understanding the displacement process and water movement within the reservoir. The integrated analysis resulted in improvements in the field practices for reservoir management and well completion design for future development wells.

Advanced Data-Driven Performance Analysis For Mature Waterfloods

“…Since the 1960s, the universally accepted approach to optimization of mature onshore waterfloods is a) to divide fields into smaller units -usually reservoir blocks or well-centered patterns -and b) to optimize performance of each unit independently, while keeping in mind overall field infrastructure constraints (see e.g., [1], [2], [3]). While modern computing power allows optimization efforts through the use of full-field simulation even for large numbers of wells (see e.g.…”