Improved Understanding of Reservoir Fluid Dynamics in the North Sea Snorre
Field by Combining Tracers, 4D Seismic, and Production Data

Huseby, Olaf; Andersen, Mona; Svorstøl, Idar; Dugstad, Øyvind

doi:10.2523/105288-ms

Cited by 12 publications

(5 citation statements)

References 4 publications

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“…In Thistle Field down-dip gas injection was applied in a IWAG scenario to target attic oil (Awan et al, 2006). Additional oil recovery was attributed to low-quality sandstone contacted by the injected gas (Laidlaw et al, 1986) The Snorre Field is fluvial sandstone with fault block trapping (Blaker et al, 1999) and beds dipping from 4 to 10 degrees (Huseby et al, 2008). The IWAG pattern consisted of down-dip injectors and up-dip producers within a central fault block.…”

Section: North Seamentioning

confidence: 99%

Immiscible Water Alternating Gas (IWAG) EOR: Current State of the Art

Holtz¹

2016

SPE Improved Oil Recovery Conference

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Enhanced oil recovery (EOR) is a general application used in mature oil fields to generate additional reserve growth. Several types of EOR applications are implemented in the oil industry. One such application is the injection of gas into a reservoir as a gas displacement recovery (GDR) mechanism to induce additional reserve growth. A specific type of GDR application is the immiscible water-alternatinggas (IWAG) displacement process. In this application a slug of water is put into an injection well, followed by gas, which exists as a separate phase from the water and oil. Water and gas injection slugs are alternated until the designed amount of gas has been injected, or as field production dictates. Continuous water (case water) is typically injected after the IWAG process.Herein, the state-of-art of IWAG EOR is described from an extensive literature review. First, the theories of the recovery mechanisms that cause IWAG to produce incremental oil are described. These mechanisms include viscosity reduction, 3-phase relative permeability, oil swelling, and oil film flow, all of which are a function of fluid and rock-fluid interactions. Next, salient laboratory studies are summarized, including micromodel and core floods. These studies test pore-level characteristics, displaying ranges of residual non-wetting phase saturations (hydrocarbons) down to 0.13 to 0.25 and incremental oil recovery ranging from 14% to 20% of OOIP. Some experiments isolate a specific recovery mechanism in order to determine its validity and contribution to recovery. Studies generally point to the conclusion that the gas type shows no discernable difference in recovery character.The paper concludes with a synopsis of results from small-scale field trials and field-scale projects in both heavy and light oil. Both simulation modeling and field trials are summarized. Projects have been implemented with varying types of gases, WAG ratios, and gas slug sizes, resulting in incremental reserve growth being reported in the range of 2 to 9%. The fundamental immiscible recovery mechanisms in IWAG can produce lower cost and faster response EOR projects, with moderate recovery efficiency gains.• N 2 • CO 2 • Flue gas (a combination of several gases from combustion) • Hydrocarbon gas, lean and enriched • Air SPE-179604-MS

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Section: North Seamentioning

confidence: 99%

Immiscible Water Alternating Gas (IWAG) EOR: Current State of the Art

Holtz¹

2016

SPE Improved Oil Recovery Conference

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“…While in the 1950s, tracer data has primarily being used to qualitatively determine the connection between injectors and producers, the technology has evolved into a quantitative method to calculate connected volumes and heterogeneity (e.g. Mishra et al 1991;Datta-Gupta et al 1997;Guan et al 2005;Dugstad 2007;Huseby et al 2008;Shook et al 2009a, Shook et al 2009b. As the tracers developed from radioactive tracers (e.g.…”

Section: Introductionmentioning

confidence: 98%

Using Tracer Data to Determine Polymer Flooding Effects in a Heterogeneous Reservoir, 8 TH Reservoir, Matzen Field, Austria

et al. 2015

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Polymer injection pilot projects aim at reducing the uncertainty and risk of full-field polymer flood implementation. The interpretation of polymer pilot projects is challenging owing to the complexity of the process and fluids moving out of the polymer pilot area. The interpretation is increasingly more complicated with the heterogeneity of the reservoir.In the polymer pilot performed in the 8 TH reservoir of the Matzen Field in Austria, a polymer injection well surrounded by a number of production wells was selected. A tracer was injected one week prior to polymer injection. The tracer showed that the flow-field in the reservoir was dramatically modified with increasing amounts of polymers injected. Despite short breakthrough times of 4-10 weeks observed for the tracer, polymer breakthrough occurred only after more than 12 months although injection and production rates have not been substantially changed.The tracer signal indicated that the reservoir is heterogeneous with high flow velocities occurring in high permeable layers. By injecting polymers, the mobility of the polymer augmented water was reduced compared with water injection and lead to flow diversion into adjacent layers. The tracer response showed that the speed of the tracer moving from injection to production wells was reduced with increasing amount of polymers injected.This response was used to assess the changes of the amount of water flowing from injection to production well. After a match for the tracer curve was obtained, adsorption, residual resistance factor and dispersivity were calculated. The results showed that even for heterogeneous reservoirs without having good conformance of the pilot, the critical parameters for polymer injection projects can be assessed by analyzing tracer and polymer response. These parameters are required to determine whether implementation of polymer injection at field scale is economically attractive.Along the flow path, an incremental recovery of about 8 % was achieved. The polymer retention and inaccessible pore volume in the reservoir was in the same range as in core floods. Incremental oil recovery owing to acceleration along the flow path was estimated at contributing to about 30 % to the overall incremental oil production due to polymer injection and 70 % to improved sweep efficiency.

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“…The newly optimized coefficients were consistent with 4D seismic observations and successfully helped to improve the water flooding strategy of the field. Huseby et al (2008) combined 4D seismic with tracer data in the Snorre field. The tracer travel time between injector and producers are used to estimate the degree of connectivity between the wells and also to validate the interwell interpretation from 4D seismic.…”

Section: Introductionmentioning

confidence: 99%

Joint Interpretation of Interwell Connectivity by Integrating 4D Seismic with Injection and Production Fluctuations

Yin¹,

MacBeth²,

Chassagne³

2015

Europec 2015

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A technique is proposed to quantitatively measure interwell connectivity by correlating multiple 4D seismic monitors to historical well production data. We make use of multiple 4D seismic surveys shot over the same reservoir to generate an array of 4D seismic differences. Then a causative relationship is defined between the 4D seismic signals and changes of reservoir fluid volumes caused by injection and production behavior. This allows us to correlate seismic data directly to well data to generate a "well2seis" volume. It is found that the distribution of the "well2seis" correlation attributes reveals key reservoir connectivity features, such as the seal of faults, inter-reservoir shale and fluid flow pathways between wells, and can therefore enhance our interpretation on interwell connectivity. Combining with conventional interwell methods that are based on injection and production rate variations, this multiple 4D seismic method is found to support the conventional interwell approaches and can provide more reliable and detailed interpretation.Our methodology is tested on a synthetic model extracted from full-field data for a Norwegian Sea reservoir, the fluid flow of which is controlled by fault compartmentalization and inter-reservoir shale. The full structural details and reservoir properties are preserved but three scenarios with different degrees of reservoir connectivity are created. It is found that proposed technique successfully detects the flow paths of the injected fluids in all reservoir scenarios. A volumetric attribute is created that accurately identifies the distinctive types of key flow barriers and conduits for each scenario that are known to be major factors influencing the reservoir dynamics. This proves that the well2seis attribute agrees with geological interpretations better than conventional well connectivity factors based on engineering data only. Additionally, the combination of the two types of methods provides a more robust tool for characterization of the reservoir connectivity by providing both quantitative degree and physical pattern of interwell communication.

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Improved Understanding of Reservoir Fluid Dynamics in the North Sea Snorre Field by Combining Tracers, 4D Seismic, and Production Data

Cited by 12 publications

References 4 publications

Immiscible Water Alternating Gas (IWAG) EOR: Current State of the Art

Immiscible Water Alternating Gas (IWAG) EOR: Current State of the Art

Using Tracer Data to Determine Polymer Flooding Effects in a Heterogeneous Reservoir, 8 TH Reservoir, Matzen Field, Austria

Joint Interpretation of Interwell Connectivity by Integrating 4D Seismic with Injection and Production Fluctuations

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