Horizontal Versus Vertical Wells: Assessment of Sweep Efficiency in a Multi-Layered Reservoir Based on Consecutive Inter-Well Tracer Tests - A Comparison Between Water Injection and Polymer EOR

2021 ◽  
Author(s):  
Bogdan-George Davidescu ◽  
Mathias Bayerl ◽  
Christoph Puls ◽  
Torsten Clemens

Abstract Enhanced Oil Recovery pilot testing aims at reducing uncertainty ranges for parameters and determining operating conditions which improve the economics of full-field deployment. In the 8.TH and 9.TH reservoirs of the Matzen field, different well configurations were tested, vertical versus horizontal injection and production wells. The use of vertical or horizontal wells depends on costs and reservoir performance which is challenging to assess. Water cut, polymer back-production and pressures are used to understand reservoir behaviour and incremental oil production, however, these data do not reveal insights about changes in reservoir connectivity owing to polymer injection. Here, we used consecutive tracer tests prior and during polymer injection as well as water composition to elucidate the impact of various well configurations on sweep efficiency improvements. The results show that vertical well configuration for polymer injection and production leads to substantial acceleration along flow paths but less swept volume. Polymer injection does not only change the flow paths as can be seen from the different allocation factors before and after polymer injection but also the connected flow paths as indicated by a change in the skewness of the breakthrough tracer curves. For horizontal wells, the data shows that in addition to acceleration, the connected pore volume after polymer injection is substantially increased. This indicates that the sweep efficiency is improved for horizontal well configurations after polymer injection. The methodology leads to a quantitative assessment of the reservoir effects using different well configurations. These effects depend on the reservoir architecture impacting the changes in sweep efficiency by polymer injection. Consecutive tracer tests are an important source of information to determine which well configuration to be used in full-field implementation of polymer Enhanced Oil Recovery.

2016 ◽  
Vol 19 (04) ◽  
pp. 655-663 ◽  
Author(s):  
Torsten Clemens ◽  
Markus Lüftenegger ◽  
Ajana Laoroongroj ◽  
Rainer Kadnar ◽  
Christoph Puls

Summary 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 because of 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 Torton Horizon (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 1 week before polymer injection. The tracer showed that the flow field in the reservoir was dramatically modified with increasing amounts of polymer injected. Despite short breakthrough times of 4 to 10 weeks observed for the tracer, polymer breakthrough occurred only after more than 12 months although injection and production rates were not substantially changed. The tracer signal indicated that the reservoir is heterogeneous, with high flow velocities occurring along a number of flow paths with a limited volume that are strongly connecting the injection and production wells. By injecting polymers, the mobility of the polymer-augmented water was reduced compared with water injection, and led 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 polymer injected. This response was used to assess the changes of the amount of water flowing from the injection well to production wells. After a match for the tracer curve was obtained, adsorption, residual resistance factor (RRF), and dispersivity were calculated. The results showed that, even for heterogeneous reservoirs without 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 that is connecting injection and production well, as shown by the tracer response, an incremental recovery of approximately 8% was achieved. The polymer retention and inaccessible pore volume (IPV) in the reservoir were in the same range as in corefloods. Incremental oil recovery caused by acceleration along the flow path was estimated at approximately 20% of the overall incremental oil production caused by polymer injection and 80% was attributed to improved sweep efficiency.


2019 ◽  
Vol 7 (4) ◽  
Author(s):  
Gloria Gyanfi ◽  
Wilberforce Nkrumah Aggrey ◽  
Ernest Ansah Owusu ◽  
Kofi Ohemeng Prempeh

With most polymers employed in polymer enhanced oil recovery exhibiting one or both non-Newtonian behaviours that is shear thickening and thinning at different shear rate, it is expedient to analyse the impact of these non-Newtonian behaviours in polymer optimisation. CMG simulation suite was employed to analyse the permeability pinch-out formation with a five (5) spot injection well pattern for a 360days simulation run using a 90days polymer injection well cycling. Shear thinning polymer was found not to be conducive for lower permeable formation as a high percentage of the polymer was retained. NPV was affected by polymer injection rate which controlled polymer optimisation


2012 ◽  
Vol 15 (02) ◽  
pp. 229-242 ◽  
Author(s):  
Hao Cheng ◽  
G. Michael Shook ◽  
Malik Taimur ◽  
Varadarajan Dwarakanath ◽  
Bruce R. Smith

Summary Enhanced oil recovery (EOR) by surfactant flooding is the key to unlocking the next billion barrels of oil for Minas, one of the world's largest waterflood fields. An interwell tracer test (ITT-1) was performed before a surfactant field trial (SFT) to ensure well injectivity, demonstrate pattern confinement, quantitatively describe interwell connectivity and sweep efficiency, and provide sufficient data for reservoir evaluation. The tracer test was designed by numerical simulation. The test started in November 2009 and was terminated in February 2010. Analytical interpretation based on moment analysis and numerical reservoir simulations was conducted to evaluate ITT-1 results. Interpretation of the test results indicated various operational and reservoir properties that would have likely led to failure of the surfactant pilot. Hydraulic control of the SFT pattern was not achieved; in fact, less than 20% of one tracer was recovered. Many small-scale heterogeneities were identified that led to a lower-than-expected reservoir volume contacted. Unexpected communication between the target sand and the underlying sands outside the pattern also contributed to low tracer recovery and low swept volume. The tracer test was history matched, and additional features were incorporated in the reservoir model, and a new tracer design (ITT-2) was optimized to correct low sweep efficiency and poor hydraulic control. New information from ITT-2 will be used to further optimize operating conditions for SFTs. Failure to conduct the tracer tests would have likely revealed these unfavorable reservoir and operational conditions during the SFT. Had oil recovery been poor (because of low swept volume), it would have erroneously been attributed to a poor SFT rather than to the true causes. ITT-1 is considered successful because it allowed us to redesign injection/hydraulic control during the relatively inexpensive tracer test and thus evaluate the surfactant trial without bias.


2019 ◽  
Vol 797 ◽  
pp. 385-392
Author(s):  
Abd Rahman Hasrizal ◽  
Najmiddin Yaakob

Some of the enhanced oil recovery (EOR) techniques involve injection of polymer brine in the formation. Addition of polymer increases the viscosity causing improved sweep efficiency owing to favorable mobility factor. Microbial induced corrosion (MIC) is caused by growth of certain bacterial species in the pipeline system and the reservoir. There is possibility of MIC to occur along the water injection schemes. Sea water is considered bereft of nutrients not allowing much bacterial activity but some sessile consortia may grow on internal line surface and cause corrosion. When the sea water is injected into the formation some anaerobic consortia dominated by sulfate reducing bacteria (SRB) grow in the formation. These bacteria use oxygen present in sulfate for respiration and volatile fatty acids (VFAs) as carbon source. But after some time of water injection the formation may get depleted of VFAs thwarting bacterial growth. This study was taken up to understand impact of EOR polymer on growth of bacterial consortium. A bacterial consortia labelled as consortia II from ATCC which is tough oilfield bacteria consortia was allowed to grow with VFA (lactate or acetate), in absence of VFA and in presence of 1000 ppm of HPAM polymer. Planktonic and sessile counts were monitored over 40 days period. Results from this study showed, microbes utilized the polymer as their secondary nutrient, whenever their preferred nutrient was depleted or insufficient. SRB sessile count which was 102 cells/cm2 in nutrient depleted medium picked up a value of 106 cells/cm2 in presence of polymer. It was observed that the bacteria first utilize the available VFA source, after that a period of lull for about 5 days followed before the growth being picked up.


2021 ◽  
Author(s):  
Artem Galimzyanov ◽  
Konstantin Naydensky ◽  
Olaf Kristoffer Huseby

Abstract Justified application of enhanced oil recovery (EOR) methods is one of the key tasks of oil operating companies for the effective development of not only brown oil fields at a mature stage of production, but also for green fields. The selection and justification of one or another method of enhanced oil recovery for certain geological conditions often requires not only looking for worldwide experience, conducting laboratory tests on a core, but also performing pilot tests at a polygon area. The subsequent full-field implementation of EOR method requires confirmation of its effectiveness based on the increase in oil recovery factor. This article describes both the experience of using interwell tracer studies to substantiate the effectiveness of EOR technologies in pilot areas, and the experience of evaluating the effectiveness of EOR technologies with full-field implementation in various fields. The work carried out on the integrated use of tracer studies makes it possible to apply a scientific and engineering approach to the selection of an enhanced oil recovery method by assessing the sweep efficiency before and after the application of the EOR technology. Examples of the use of this integrated approach for different oil fields are given. The presented technologies and experience of the work performed will significantly speed up the choice of the EOR technology for certain geological conditions and verify the effectiveness of the selected EOR method.


2021 ◽  
pp. 014459872098020
Author(s):  
Ruizhi Hu ◽  
Shanfa Tang ◽  
Musa Mpelwa ◽  
Zhaowen Jiang ◽  
Shuyun Feng

Although new energy has been widely used in our lives, oil is still one of the main energy sources in the world. After the application of traditional oil recovery methods, there are still a large number of oil layers that have not been exploited, and there is still a need to further increase oil recovery to meet the urgent need for oil in the world economic development. Chemically enhanced oil recovery (CEOR) is considered to be a kind of effective enhanced oil recovery technology, which has achieved good results in the field, but these technologies cannot simultaneously effectively improve oil sweep efficiency, oil washing efficiency, good injectability, and reservoir environment adaptability. Viscoelastic surfactants (VES) have unique micelle structure and aggregation behavior, high efficiency in reducing the interfacial tension of oil and water, and the most important and unique viscoelasticity, etc., which has attracted the attention of academics and field experts and introduced into the technical research of enhanced oil recovery. In this paper, the mechanism and research status of viscoelastic surfactant flooding are discussed in detail and focused, and the results of viscoelastic surfactant flooding experiments under different conditions are summarized. Finally, the problems to be solved by viscoelastic surfactant flooding are introduced, and the countermeasures to solve the problems are put forward. This overview presents extensive information about viscoelastic surfactant flooding used for EOR, and is intended to help researchers and professionals in this field understand the current situation.


2021 ◽  
pp. 79-90
Author(s):  
Т. A. Pospelova

The article discusses ways to increase the oil recovery factor in already developed fields, special attention is paid to the methods of enhanced oil recovery. The comparative structure of oil production in Russia in the medium term is given. The experience of oil and gas companies in the application of enhanced oil recovery in the fields is analyzed and the dynamics of the growth in the use of various enhanced oil recovery in Russia is estimated. With an increase in the number of operations in the fields, the requirements for the selection of candidates inevitably increase, therefore, the work focuses on hydrodynamic modeling of physical and chemical modeling, highlights the features and disadvantages of existing simulators. The main dependences for adequate modeling during polymer flooding are given. The calculation with different concentration of polymer solution is presented, which significantly affects the water cut and further reduction of operating costs for the preparation of the produced fluid. The possibility of creating a specialized hydrodynamic simulator for low-volume chemical enhanced oil recovery is considered, since mainly simulators are applicable for chemical waterflooding and the impact is on the formation as a whole.


2018 ◽  
Vol 3 (44) ◽  
pp. 12461-12468
Author(s):  
Lei Jiang ◽  
Jingtao Sun ◽  
Jiqian Wang ◽  
Qi Xue ◽  
Songyan Li ◽  
...  

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