Magnus WAG Pattern Optimization Through Data Integration
- Demet Erbas (BP) | Matthew Dunning (BP) | Timothy M. Nash (BP) | David Cox (BP) | John A. Stripe (BP) | Euan Duncan (BP)
- Document ID
- Society of Petroleum Engineers
- SPE Improved Oil Recovery Symposium, 12-16 April, Tulsa, Oklahoma, USA
- Publication Date
- Document Type
- Conference Paper
- 2014. Society of Petroleum Engineers
- 5.1.7 Seismic Processing and Interpretation, 5.6.4 Drillstem/Well Testing, 1.6 Drilling Operations, 7.6.2 Data Integration, 3.3.1 Production Logging, 5.4.2 Gas Injection Methods, 5.1.9 Four-Dimensional and Four-Component Seismic, 4.3.4 Scale, 5.2.1 Phase Behavior and PVT Measurements, 6.3.6 Chemical Storage and Use, 2.4.3 Sand/Solids Control, 5.4 Enhanced Recovery, 5.4.1 Waterflooding, 5.5.8 History Matching, 4.1.5 Processing Equipment, 5.5.11 Formation Testing (e.g., Wireline, LWD), 2.2.2 Perforating, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 4.1.2 Separation and Treating, 1.6.9 Coring, Fishing, 5.7.2 Recovery Factors
- gas sweep, pattern optimization, 4D monitoring gas, WAG surveillance, pattern reversal
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Magnus tertiary miscible gas injection started in 2002 through a WAG scheme yielding 18 mmstb of incremental oil to date at a very high net efficiency of 3.5 mscf/stb. Pore scale efficiency is very good with 8% Sorm based on core flood data. Areal and vertical gas sweep efficiency is sub-optimal based on 4D seismic and PLT data. This paper focuses on studies carried out to explore possibilities to improve sweep efficiency and the resulting pattern optimization programme in the field.
Magnus Sandstone Member (MSM) consists of a number of stacked turbidite sand lobes separated by intra-formational shales. The WAG scheme has been managed by considering MSM as a single reservoir unit. As the patterns have matured, it has become apparent that the scheme could be optimized by further vertical separation of the reservoir units. Key surveillance data such as 4D seismic monitoring gas movement, PLTs, well performance and open hole saturation logs have been coupled with simulation to explore options for sweep improvement. These options involve changing sweep direction by means of adding new perforations and shutting off zones, complete reversal of the patterns – i.e. converting producers to injectors and vice versa, and use of chemicals for flood diversion.
Evaluation of multiple options resulted in a phased WAG optimization programme of which the first phase is being proposed for execution in 2014. A behind flood front core is planned in 2015, which is expected to help calibrate the optimization programme by quantifying Sorm and the degree of vertical sweep achieved in the field. Relatively low cost options were identified to improve the sweep as opposed to drilling new wells. Integration with the operations team was the key in creating a business case for pattern optimization on a 30-yrs old, bed space constrained platform.
The workflow of this study and the learnings are applicable to mature patterns in any WAG scheme. Optimizing the WAG patterns enables more efficient use of the available gas, which -given that cost of gas is a significant component of any gas injection project- makes this more commercially viable and cost effective tertiary recovery option.
|File Size||7 MB||Number of Pages||12|