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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)
Numerical Interpretation of Single Well Chemical Tracer Tests for ASP Injection
de Zwart, A. H. (Shell Development Oman) | Stoll, W. M. (Shell Development Oman) | Boerrigter, P. M. (Shell Development Oman) | van Batenburg, D. W. (Shell Global Solutions International BV) | Al Harthy, S. S. (Petroleum Development Oman)
Abstract A series of single well injection tests has been conducted to estimate the efficiency of Alkaline Surfactant Polymer (ASP) flooding. These injection tests comprised a Single Well Chemical Tracer (SWCT) test that was done after water injection to establish a baseline remaining oil saturation and a second SWCT test conducted after ASP injection to measure the Remaining Oil Saturation (ROS) after ASP. Analytical methods are generally used to interpret SWCT tests and to determine the remaining oil saturation. These techniques work best when the response is close to an ideal, single peak. However, the responses from the SWCT tests in our single well tests sequences are complex, showing multiple peaks. This is indicative of complicating factors such as cross-flow between layers. To understand the complex response we used numerical simulation techniques to interpret the SWCT tests. The numerical model includes the physics of ASP, such as interfacial tension reduction, water viscosity modification, and the related reduction in ROS as wells as an accurate model for tracer dispersion. The model allows full control of physical dispersion and does not require the use of numerical diffusion to mimic the effect of physical dispersion. The numerical simulation sequence involves the full single well injection test history including SWCT tests before and after the ASP injection. The key challenge in matching the tests results with the numerical simulations was to model the complex response, which was different for each well tested. Elaborate numerical simulations, different from the conventional interpretation method, were used to successfully match all tests. This paper presents the simulation work, an explanation of the parameters varied to obtain agreement between numerically predicted and actual SWCT responses and the numerical simulation tools used to match the SWCT tests.
- Asia (0.93)
- Europe (0.93)
- North America > United States > Oklahoma (0.46)
- North America > United States > Texas (0.28)
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.34)
- South America > Venezuela > Lake Maracaibo > Maracaibo Basin > Lagomar Field (0.99)
- North America > United States > California > West Coyote Field (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 375 > Block 34/7 > Snorre Field > Statfjord Group (0.99)
- (13 more...)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Tracer test analysis (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Drillstem/well testing (1.00)
Abstract This paper presents the first results of an ongoing experimental work at IFE for developing new tracers to be used for estimation of remaining oil saturation. The methodology is based on the chromatographic theory, which states that various components flowing through porous media will be delayed according to their partition coefficient to the immobile phase. Two experiments, one with gas tracers and the other with water tracers, are presented here, demonstrating the applicability of the methodology in the laboratory scale. Moreover, a numerical model (ITRC-SIM module) developed at IFE especially for simulating the tracer flow in hydrocarbon reservoirs is validated against the experimental data and used to demonstrate the use of tracers in small and field scale generic cases. Introduction Tracers are inert chemical compounds widely used to improve the description of hydrocarbon and water reservoirs. Water tracers are divided into two categories: the ideal (or passive) tracers, which always follow the aqueous phase, and the partitioning tracers, which partition between the aqueous and the oil phase. Ideal tracers are used mainly in interwell tracer tests in order to obtain information about the flow patterns and to establish the velocity field and the well continuity. The tracer data can also be used to upgrade a reservoir modelPartitioning tracers, which are the subject of this paper, are used in hydrocarbon reservoirs in both single well tracer tests and inter-well tracer tests to estimate the residual oil saturation usually prior to enhanced oil recovery applications The gas tracers are always partitioning between the oil and gas phases. The most commonly applied water tracers are tritiated water (HTO), thiocyanade and some mono fluoro benzoic acids. The most commonly used gas tracers are tritiated methane, SF6 and several perfluorocarbons with low partitioning to oil phase. In this paper, the first results of an experimental evaluation of new gas and water partitioning tracers for the estimation of remaining oil saturation in hydrocarbon reservoirs are presented. A numerical model, (ITRC-SIM) built with advanced physical and numerical features, has been developed and validated against the experimental data. Finally, the application of partitioning tracers in oil reservoirs is discussed in small and field scale generic cases. Partitioning Tracers for Estimation of Residual Oil Saturation When ideal and partitioning water tracers are injected simultaneously in an oil reservoir, the ideal tracers will flow only in the water phase adopting the velocity of this phase. On the other hand, the molecules of the partitioning tracers are moving back and forth between the water and oil phase. Consequently the partitioning tracer molecules are flowing with the water velocity when they are in the water phase and the oil velocity when they are in the oil phase. As a result of this chromatographic effect there is a net time delay on the arrival of the partitioning tracers at the production well compared with the arrival time of the ideal tracers. This time delay depends on the partitioning coefficients (which can be measured in the laboratory) and the oil saturation. The same methodology can be applied in a gas-oil system with the use of two gas tracers with different partitioning coefficients.
- Geophysics > Seismic Surveying (0.54)
- Geophysics > Borehole Geophysics (0.41)
- 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...)
Abstract The technical success of an Enhanced Oil Recovery (EOR) project depends on two main factors - first, the reservoir remaining oil saturation (ROS) after primary and secondary operations, and second, the recovery efficiency of the EOR process in mobilizing the ROS. These two interrelated parameters need to be estimated prior to embarking on a time-consuming and costly process for designing and implementing an EOR process. The oil saturation can vary areally and vertically within the reservoir, and the distribution of the ROS will determine the success of the EOR injectants in mobilizing the remaining oil. There are many methods for determining the oil saturation (Chang et al. 1988, Pathak et al. 1989) and these include core analysis, well log analysis, Log-Inject-Log (LIL) procedures (Richardson 1973 and Reedy 1984), and Single Well Chemical Tracer Tests (SWCTT). These methods have different depths of investigation and different accuracies, and they all provide valuable information about the distribution of ROS. There is no single method that provides the best estimate of ROS, and a combination of all these methods is essential in developing a holistic picture of oil saturation and in assessing whether the oil in place is large enough to justify the application of an EOR process. As Teletzke et al. (2010) have shown, EOR implementation is a complex process, and a staged, disciplined approach to identifying the key uncertainties and acquiring data for alleviating the uncertainties is essential. The largest uncertainty in some cases is the remaining oil saturation in the reservoir. This paper presents the results from a field-wide data acquisition program conducted in a West Texas carbonate reservoir to estimate ROS as part of an EOR project assessment. The Means field in West Texas has been producing for more than the past 75 years and the producing mechanisms have included primary recovery, secondary waterflooding and the application of a CO2 EOR process. The Means field is an excellent example of how the productive life and oil recovery can be increased by the application of new technology. The Means story is one of judicious application of appropriate EOR technology to the sustained development of a mature asset. The Means field is currently being evaluated for further expansion of the EOR process and it was imperative to evaluate the oil saturation in the lower, previously-undeveloped zones. This paper briefly outlines the production history, reservoir description and reservoir management of the Means field, but this paper concentrates on the Residual Oil Zone (ROZ) that underlies the Main Producing Zone (MPZ), and describes a recent data acquisition program to evaluate the oil saturation in the ROZ. We discuss three major methods for evaluating the ROS - core analysis, LIL tests and SWCTT tests.
- Research Report (0.93)
- Overview > Innovation (0.34)
- Geology > Geological Subdiscipline (0.93)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.46)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (28 more...)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- (6 more...)
Abstract The success of any improved oil recovery (IOR) project is largely dependent on how much oil is remaining to be mobilized within the targeted area of the partially depleted or mature reservoir. Partitioning tracers are generally used to measure residual oil saturation (Sor) or remaining oil saturation (ROS) in the near wellbore region via a single well chemical tracer test (SWCTT) or in an inter-well region via a partitioning inter-well tracer test (PITT). There is a limited repertoire of nonradioactive and environmentally friendly inter-well partitioning tracers for measuring ROS. A new class of environmentally friendly partitioning tracers was field tested, in a giant carbonate reservoir undergoing peripheral waterflood, for measuring ROS in inter-well regions in a depleted area. The new partitioning tracers were qualified via laboratory experiments and are deemed to be very stable at reservoir conditions (213°F and a salinity range of 60-200 kppm). The field pilot was conducted concurrently with a set of non-partitioning inter-well chemical tracer test (IWCTT) to determine reservoir connectivity, water breakthrough times, and injector-to-producer pair communication in an area selected for an IOR/EOR field pilot. An elaborate sampling and analysis program was carried out over a period of 30 months. This paper reviews the complete design and implementation of the test, operational issues, and the analyses and interpretation of the results. The breakthrough times of the passive and partitioning tracers are reported, and inter-well connectivity between the paired and cross-paired injectors and producers are analyzed. The ROS measured by a majority of the novel tracers is comparable to the saturations obtained via SWCTT, core and log derived saturations. The combination of conventional IWCTT and the novel partitioning tracers via PITT has been very useful in analyzing well interconnectivity, understanding the reservoir dynamics and quantifying remaining oil saturation distribution in the reservoir. This has led to better reservoir description and an improved dynamic simulation model.
- North America > United States > Texas (0.46)
- Europe > United Kingdom > North Sea > Central North Sea (0.45)
- North America > United States > Oklahoma (0.29)
- Asia > Middle East > UAE (0.28)
- 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)