Single Well Chemical Tracer Tests - Fast and Accurate Simulations

Huseby, Olaf; Sagen, Jan; Dugstad, Øyvind

doi:10.2118/155608-ms

Cited by 37 publications

(10 citation statements)

References 18 publications

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“…8). Integrating to infinite production volume implied that approximately 60% of the injected EtAC would eventually be produced; this attrition has been explained in other publications as stripping of EtAC when gas breaks out of produced water or irreversible losses to the reservoir (Jerauld et al 2010). Fig.…”

Section: History Match: Well B Test Nomentioning

confidence: 84%

“…Reactive, partitioning SWTTs are used to measure the saturation of an immobile phase (oil, water, or gas) near a wellbore Carlisle, 1986, 2007;Hernandez et al 2002;Jerauld et al 2010;Abdul Manap et al 2011;Carlisle et al 2014). To measure the ROS to water (S orw ) with an SWTT, a large volume of water must first be injected into a producing well until oil in the investigated region is immobile.…”

Section: Introductionmentioning

confidence: 99%

“…Oil saturation, cell volume, layer injected volume, layer produced volume, tracer-reaction coefficient (a), and partition coefficient (K) can be modified to accurately match the producedtracer concentrations and thereby determine ROS (Deans and Carlisle 2007;Jerauld et al 2010;Carlisle et al 2014). Such simulations are fast and inexpensive but do not comprehensively evaluate the entire one-spot process, including EOR physics and communicating reservoir layers (Huseby et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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Design and Demonstration of New Single-Well Tracer Test for Viscous Chemical Enhanced-Oil-Recovery Fluids

et al. 2016

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Single-well-partitioning-tracer tests (SWTTs) are used to measure the saturation of oil or water near a wellbore. If used before and after injection of enhanced-oil-recovery (EOR) fluids, they can evaluate EOR flood performance in a so-called one-spot pilot. Four alkaline/surfactant/polymer (ASP) one-spot pilots were recently completed in Kuwait's Sabriyah-Mauddud (SAMA) reservoir, a thick, heterogeneous carbonate operated by Kuwait Oil Company (KOC). UTCHEM (Delshad et al. 2013), the University of Texas chemical-flooding reservoir simulator, was used to interpret results of two of these one-spot pilots performed in an unconfined zone within the thick SAMA formation. These simulations were used to design a new method for injecting partitioning tracers for one-spot pilots. The recommended practice is to inject the tracers into a relatively uniform confined zone, but, as seen in this work, that is not always possible, so an alternative design was needed to improve the accuracy of the test.The simulations showed that there was a flow-conformance problem when the partitioning tracers were injected into a perforated zone without confinement after the viscous ASP and polymer-drive solutions. The water-conveyed-tracer solutions were being partially diverted outside of the ASP-swept zone where they contacted unswept oil. Because of this problem, the initial interpretation of the performance of the chemicals was pessimistic, overestimating the chemical residual oil saturation (ROS) by up to 12 saturation units. Additional simulations indicated that the oil saturation in the ASP-swept zone could be properly estimated by avoiding the post-ASP waterflood and injecting the post-ASP tracers in a viscous polymer solution rather than in water. An ASP one-spot pilot using the new SWTT design resulted in an estimated ROS of only 0.06 after injection of chemicals (Carlisle et al. 2014). These saturation values were obtained by history matching tracer-production data by use of both traditional continuously-stirred-tank (CSTR) models and compositional, reactivetransport reservoir models.The ability of the simulator to model every phase of the onespot pilot operation was crucial to the insight of modified SWTT design. The waterflood, first SWTT, ASP flood, and the final SWTT were simulated using a heterogeneous permeability field representative of the Mauddud formation. Laboratory data, field-ASP quality-control information, and injection strategy were all accounted for in these simulations. We describe the models, how they were used, and how the results were used to modify the SWTT design. We further discuss the implications for other SWTTs.The advantage of mechanistic simulation of multiple aspects of a one-spot pilot is an important theme of this study. Because the pore space investigated by the SWTTs can be affected by the previously injected EOR fluids (and vice versa), these interactions should be accounted for. This simulation approach can be used to identify and mitigate design problems during each phase of a challenging one-s...

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Section: History Match: Well B Test Nomentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Design and Demonstration of New Single-Well Tracer Test for Viscous Chemical Enhanced-Oil-Recovery Fluids

et al. 2016

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“…The numerical solution of the tracer problem exploits the assumption that tracers do not influence the phase transport (Sagen et al, 1996;Huseby et al, 2012). The pressure, saturations and flow fields, which are the solution of the problem as the tracers would not exist, are computed and stored by the simulator ECLIPSE™ 100.…”

Section: Tracer Transport Modelingmentioning

confidence: 99%

Low Salinity Waterflooding: From Single Well Chemical Tracer Test Interpretation to Sector Model Forecast Scenarios

Spagnuolo

Callegaro

Masserano

et al. 2016

SPE Improved Oil Recovery Conference

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We study Enhanced Oil Recovery (EOR) through Low Salinity (LS) waterflooding in a brown oil field. LS waterflooding is an emerging EOR technique in which water with reduced salinity is injected into a reservoir to improve oil recovery, as compared with conventional waterflooding, in which High Salinity (HS) brine or seawater are commonly used. The efficiency of this technique can be quantified at the well-scale by a Single Well Chemical Tracer Test (SWCTT), which is an in-situ method for measuring the Remaining Oil Saturation (ROS) after flooding the near-wellbore region with a displacing agent. Two SWCTTs were executed on a sandstone North African field. The tests were realized in sequence with seawater and LS water to evaluate the EOR potential at the well-scale.Here, we propose the interpretation of these two SWCTTs. They were modeled through numerical simulations because of the presence of several non-idealities in the complex scenario considered. A recently-developed tracer simulator was employed to solve the reactive transport problem. This was used as a fast post-processing tool coupled with a conventional reservoir simulator. Model parameters were estimated within an inverse modeling framework, on the basis of an assisted history matching procedure that exploits the Metropolis Hastings Algorithm (MHA). Results were scaled up on a sector model of the field, and forecast scenarios that consider a field-scale implementation of this technique were defined.The well-scale displacement efficiency gain associated with LS water, as compared with seawater, was evaluated. It was quantified as a ROS reduction of 8 saturation unit (s.u.), with a P10 -P90 range of 3-15 s.u. Reservoir-scale simulations suggest that the associated ultimate oil recovery of the EOR pilot may be increased by 2% with LS water, with a P10 -P90 range of 0.7-4.3%.Overall, the LS EOR potential for a selected field was quantified through a robust and original workflow, based on SWCTT interpretation. This state-of-the-art procedure is now available for further applications. The simulated oil recovery improvement with LS water is promising, and leads the way to the implementation of an inter-well field trial. IntroductionWaterflooding performance may be affected by the salinity of the displacing water (Rotondi et al., 2014). In particular, the injection of water with reduced salinity may improve oil recovery, as compared with conventional waterflooding, in which HS brine or seawater are commonly used. This was firstly investigated by Tang and Morrow (1999), who proposed the migration of fines theory to underpin the observed incremental oil recovery. Since then, several mechanisms, different in sandstone and carbonate reservoirs, have been proposed to explain the ensuing EOR effect, with various degrees of acceptance in the industry (McGuire et al., 2005;Pu et al., 2010;Emadi & Sohrabi, 2013). Today, the two most recognized mechanisms are based on (a) the occurrence of multicomponent ion exchange and (b) the effects of pH on the desorption from the...

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“…The reservoir simulator used in this work was UTCHEM, a three-dimensional, multiphase, multicomponent chemical flooding simulator developed in the Center for Petroleum and Geosystems Engineering at The University of Texas at Austin (Pope et al, 1978, Delshad et al, 2006. This case has chosen for validation the simulation methodology because it can be represented by a simple one-layer reservoir simulation model (Huseby et al, 2012).…”

Section: Swct Testmentioning

confidence: 99%

Numerical Interpretation of Single Well Chemical Tracer (SWCT) Tests to Determine Residual Oil Saturation in Snorre Reservoir

2015

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Determination of residual oil saturation (S or ) is heavily required for evaluating the effect of EOR methods. While there are some methods to determine S or 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 S or 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 S or are obtained. The S or 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 S or 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 S or 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 S or 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 unk...

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Single Well Chemical Tracer Tests - Fast and Accurate Simulations

Cited by 37 publications

References 18 publications

Design and Demonstration of New Single-Well Tracer Test for Viscous Chemical Enhanced-Oil-Recovery Fluids

Design and Demonstration of New Single-Well Tracer Test for Viscous Chemical Enhanced-Oil-Recovery Fluids

Low Salinity Waterflooding: From Single Well Chemical Tracer Test Interpretation to Sector Model Forecast Scenarios

Numerical Interpretation of Single Well Chemical Tracer (SWCT) Tests to Determine Residual Oil Saturation in Snorre Reservoir

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