Understanding Reservoir Architectures and Steam Chamber Growth at Christina Lake, Alberta, by Using 4D Seismic and Crosswell Seismic Imaging

Abstract

The Christina Lake Thermal Project, located 170 km South of Fort McMurray, Alberta, uses steam-assisted gravity drainage (SAGD) technology to recover bitumen from the McMurray formation. The bitumen reservoir at Christina Lake is approximately 400m deep, and is delineated by over 300 vertical wells and extensive 3D seismic coverage. The McMurray formation can be informally subdivided into three units -Lower, Middle and Upper. The Middle unit contains the major bitumen bearing reservoir, while the Lower unit is generally water bearing and the Upper unit typically contains gas with some residual bitumen saturation. SAGD at Christina Lake was first implemented in 2001 (Phase 1, Figure 1). The currently developed project area is covered by time-lapse surface 3D seismic and crosswell seismic.The 3D survey was acquired using mega-bin geometry, with a bin size of 12.5 m by 12.5 m. A baseline survey was conducted in 2001 followed by two repeat surveys in 2004 and 2005. In addition, six crosswell seismic profiles were acquired by placing both sources and receivers in vertical wellbores. The goal of the survey is to better understand reservoir architecture by detecting lithology changes, including predicting the occurrence of mudstone stringers and their lateral and vertical distribution. Crosswell seismic data in this project have provided about one metre vertical resolution in the McMurray Formation, detected mudstone stringers, and indicated significant reservoir heterogeneity, all of which helped to more accurately characterize the reservoir and better predict reservoir performance under thermal operations. Results of the six profiles provide encouraging insight into the potential of crosswell seismic technology. Although there is a need for future research in several areas, crosswell seismic has the potential to complement and enhance the interpretation of surface 3D seismic.Analysis of both 4D and crosswell data showed that steam chamber growth and oil recovery are strongly influenced by reservoir geology. Steam chamber growth is especially affected by the presence of low permeability facies in the vicinity of the SAGD well pairs. In each case to date, less than 100% of the well length contributes to oil production. These findings have significant impacts on the planning of future developments.

Analysis of Heavy Oil Recovery by Thermal EOR in a Meander Belt: From Geological to Reservoir Modeling

“…For example, the steam chamber growth has been observed using 4D and crosswell seismic images at the Christina Lake SAGD project (Zhang et al, 2007). This study clearly showed that the steam chamber growth was not regular.…”

“…The upscaling was performed using CobraFlow ™ while the SAGD reservoir simulations were performed using PumaFlow ™ . The results were analysed to see if the upscaling factor influences the description of the heterogeneities, a central issue in SAGD production (Birell and Putnam, 2000;Robinson et al, 2005, Zhang et al, 2005Chen et al, 2007;Lerat et al, 2010).…”

Heterogeneity Impact on SAGD Process Performance in Mobile Heavy Oil Reservoirs

“…Oil rates in excess of 100 m 3 /d have been achieved with 500 m long well pairs. On other fields, 4D seismic results show that fractions of wellbores do not have steam chamber development along their length due to geological heterogeneity (Zhang et al, 2005). Jimenez (2008) reviewed a large database of SAGD operations in Canada.…”

Enhanced heavy oil recovery for carbonate reservoirs integrating cross-well seismic – A synthetic Wafra case study

“…Zhang et al (2012) utilized cross-well seismic tomography for monitoring the CO 2 injection process for the Ketzin field in Germany, and showed a clear seismic signal anomaly for the CO 2 injection process. For heavy oil reservoirs, cross-well seismic tomography was used for monitoring the reservoir architecture and steam chamber growth as shown in (Zhang et al, 2007) for the Christina Lake heavy oil reservoir in Canada. The authors indicated that the reservoir heterogeneity may significantly influence the growth process of the steam chamber that was also detected via cross-well seismic data.…”