Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
The first SWCT test for Sor was run in the East Texas Field in 1968.[1] Patent rights were issued in 1971.[2] Since then, numerous oil companies have used the SWCT method.[3][4][5][6][7] More than 400 SWCT tests have been carried out, mainly to measureSor after waterflooding. The SWCT method has gained considerable recognition over the past few years because of increasing interest in the quantitative measurement ofSor. Some experts[8][9] consider the SWCT test to be the method of choice because of its demonstrated accuracy and reasonable cost.
- North America > United States > Texas (1.00)
- North America > United States > Alaska > North Slope Borough > Prudhoe Bay (0.28)
- North America > United States > Texas > East Texas Salt Basin > East Texas Field > Woodbine Formation (0.99)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Eugene Island > Block 193 > Bay St. Elaine Field (0.99)
- North America > United States > California > West Coyote Field (0.99)
- (2 more...)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
Simple analytical interpretation of single well chemical tracer (SWCT) is possible if one assumes uniform oil saturation, negligible hydrolysis during injection and production and assuming similar dispersion for all reservoir layers. In complex reservoir settings, including multilayer test zones, drift, cross-flow etc., reservoir simulation tools, capable of handling the hydrolysis reaction are commonly applied (Jerauld et al., 2010; Skrettingland et al., 2011). In practice, coupled flow and chemical reaction simulators (see e.g. CMG, 2010; and UTCHEM, 2000) are used. Such coupled simulations are CPU-demanding enough that execution time may be an issue, especially when small grid-size are applied to avoid numerical smearing. A significantly simpler and faster approach is possible by exploiting the fact that tracers do not influence on the fluid flow in the reservoir.
Using the single well chemical tracer (SWCT) test avoids the problems of too-wide well spacing and excessive tracer dispersion caused by layering that can occur withwell to well tests. In the SWCT test, the tracer-bearing fluid is injected into the formation through the test well and then produced back to the surface through the same well. The time required to produce the tracers back can be controlled by controlling the injected volume on the basis of available production flow rate from the test well. In a single-well test, tracers injected into a higher-permeability layer will be pushed farther away from the well than those in a lower-permeability layer, as indicated inFigure 1a; however, the tracers in the higher-permeability layer will have a longer distance to travel when flow is reversed. As the tracer profiles inFigure 1b show, the tracers from different layers will return to the test well at the same time, assuming that the flow is reversible in the various layers.
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
Abstract Determination of residual oil saturation (Sor) is heavily required for evaluating the effect of EOR methods. While there are some methods to determine Sor such as coring, logging, and tracer methods, it is generally accepted that tracer methods are more efficient mainly due to the measurement of large reservoir volume and non-dependency on porosity. Among all proposed tracer methods to determine Sor of EOR methods, only Single Well Chemical Tracer (SWCT) method is widely implemented in the industry. Several SWCT tests have been carried out in Snorre reservoir to evaluate the effect of injection of high, drill, and lowsal waterflooding. Since characteristics of each SWCT test is unique and often is different even on the same well in various tests, simulation procedure for finding multiple history matches to the measured tracer production from the field is a challenging process. In this paper, the numerical interpretation of first SWCT test after high salinity waterflooding is done. The necessary parameters to model the field test and the value of numerical interpretation of SWCT tests is also introduced. UTCHEM is used as the numerical simulation tool to get an acceptable history match to the measured field data. The procedure of interpretation is started with a single-layer (ideal) model. The unknown parameters that affect tracer production are grid size, hydrolysis reaction rate, and average Sor are obtained. The Sor is determined 0.24 in the present test in the original reservoir temperature of 194 °F. While ideal model shows a worthy fit, there is still some deviation between measured and modelled profiles at the tail of the curves because of non-ideality effects. Flow irreversibility in layered test zones is considered for departing ideal model from the real test in this sandstone reservoir. The three new unknown parameters of non-ideal model are the number of layers in the test zone, the fraction of total fluid injected and produced from each layer, and the Sor for each layer. In the interpretation of the present test, two other layers are added to determine the effect of flow irreversibility in test zone. The main layer, the early layer, and the late layer accepted and produced 52%, 17%, and 31% of the total injected tracer, respectively. The average Sor of 0.22, 0.24, and 0.26 is resulted to the main layer, the early layer, and the late layer, respectively. The best history match without any deviation between modelled and measured profiles is obtained using non-ideal model. According to the reservoir cooling and heating from shale layers above and below the flooded sand interval, the temperature of the fluids near-wellbore will change. Since the tracer bank is injected with lower temperature than reservoir temperature, the effect of reservoir cooling on the ester partitioning coefficient is investigated in order to determine Sor more precisely. Using this numerical SWCT interpretation, it is achievable to examine other EOR methods to reach more oil recovery in this sandstone reservoir via obtained unknown parameters.
- Asia (1.00)
- North America > United States > Oklahoma (0.29)
- North America > United States > Texas (0.28)
- Europe > Norway > North Sea > Northern North Sea (0.15)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.95)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.54)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/7 > Snorre Field > Statfjord Group (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/7 > Snorre Field > Lunde Formation (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/4 > Snorre Field > Statfjord Group (0.99)
- (9 more...)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Reduction of residual oil saturation (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Tracer test analysis (1.00)
Abstract Single well chemical tracer tests (SWCTT) have been extensively used in the field to estimate residual oil saturation in a reservoir for more than 50 years. They are often used as characterization methods to gauge EOR potential/performance. Therefore, an accurate estimation of Sor from SWCTT's is critical. Current approaches for SWCTT interpretation use a combination of history matching with numerical modeling tools or use of an approximate analytical technique developed for partitioning interwell tracers. History matching is more accurate, requires multiple assumptions and can be potentially time consuming. The basic analytical solution for partitioning inter-well tracer neglects tracer hydrolysis and provides approximate estimations of Sor. We solve for the exact solution of the 1-D convection-reaction solution using the modified method of moments. No additional simplifying assumptions such as slow reaction rate, fast flowback etc. were made while solving the flow equation. We tested the resulting exact solution against synthetic numerical simulations and 50+ published field cases and compared actual versus calculated oil saturations. The synthetic tracer data was generated for different heterogeneities, tracer reaction rate, partition coefficients and tracer soak time. Analysis of the synthetic SWCTT result shows that our analytical approach correctly estimates oil saturation. The calculated residual oil from our analytical model was consistently within ±0.02 saturation units while the original analytical model consistently underpredicts oil saturation. Novelty of this model is in its simplicity in calculating residual oil saturation from SWCTT's. The model requires only tracer concentration histories as an input to be able to calculate the near-wellbore residual oil saturation. The developed method can be solved directly in Microsoft excel without requiring any advanced computation/simulation tools.
- Asia > Middle East > Kuwait (0.28)
- North America > United States > Texas (0.28)
- Research Report > New Finding (0.49)
- Research Report > Experimental Study (0.34)
- Overview > Innovation (0.30)
- North America > United States > California > West Coyote Field (0.99)
- Asia > Middle East > Kuwait > Ahmadi Governorate > Arabian Basin > Widyan Basin > Greater Burgan Field > Wara Formation (0.99)
- Asia > Middle East > Kuwait > Ahmadi Governorate > Arabian Basin > Widyan Basin > Greater Burgan Field > Ratawi Formation (0.99)
- (5 more...)