Novel Insights Into Mechanisms of Oil Recovery by Use of Low-Salinity-Water Injection

SPE Journal ◽  
2016 ◽  
Vol 22 (02) ◽  
pp. 407-416 ◽  
Author(s):  
M.. Sohrabi ◽  
P.. Mahzari ◽  
S. A. Farzaneh ◽  
J. R. Mills ◽  
P.. Tsolis ◽  
...  
Keyword(s):  
Crude Oil ◽  
Oil Recovery ◽  
Water Injection ◽  
Wettability Alteration ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Salinity Water ◽  
Low Salinity Water Injection ◽  
Fluid Interactions

Summary The underlying mechanism of oil recovery by low-salinity-water injection (LSWI) is still unknown. It would, therefore, be difficult to predict the performance of reservoirs under LSWI. A number of mechanisms have been proposed in the literature, but these are controversial and have largely ignored crucial fluid/fluid interactions. Our direct-flow-visualization investigations (Emadi and Sohrabi 2013) have revealed that a physical phenomenon takes place when certain crude oils are contacted by low-salinity water, leading to a spontaneous formation of micelles that can be seen in the form of microdispersions in the oil phase. In this paper, we present the results of a comprehensive study that includes experiments at different scales designed to systematically investigate the role of the observed crude-oil/brine interaction and micelle formation in the process of oil recovery by LSWI. The experiments include direct-flow (micromodel) visualization, crude-oil characterization, coreflooding, and spontaneous-imbibition experiments. We establish a clear link between the formation of these micelles, the natural surface-active components of crude oil, and the improvement in oil recovery because of LSWI. We present the results of a series of spontaneous- and forced-imbibition experiments carefully designed with reservoir cores to investigate the role of the microdispersions in wettability alteration and oil recovery. To further assess the significance of this mechanism, in a separate exercise, we eliminate the effect of clay by performing an LSWI experiment in a clay-free core. Absence of clay minerals is expected to significantly reduce the influence of the previously proposed mechanisms for oil recovery by LSWI. Nevertheless, we observe significant additional oil recovery compared with high-salinity-water injection (HSWI) in the clay-free porous medium. The additional oil recovery is attributed to the formation of micelles stemming from the crude-oil/brine-interaction mechanism described in this work and our previous related publications. Compositional analyses of the oil produced during this coreflood experiment indicate that the natural surface-active compounds of the crude oil had been desorbed from the rock surfaces during the LSWI period of the experiment when the additional oil was produced. The results of this study present new insights into the fundamental mechanisms involved in oil recovery by LSWI and new criteria for evaluating the potential of LSWI for application in oil reservoirs. The fluid/fluid interactions revealed in this research can be applied to oil recovery from both sandstone and carbonate oil reservoirs because they are mainly derived from fluid/fluid interactions that control wettability alteration in both sandstone and carbonate rocks.

scholarly journals Effect of ionic strength in low salinity water injection processes

2020 ◽  
Vol 10 (2) ◽  
pp. 17-26
Author(s):  
Gustavo Maya Toro ◽  
Luisana Cardona Rojas ◽  
Mayra Fernanda Rueda Pelayo ◽  
Farid B. Cortes Correa
Keyword(s):  
Ionic Strength ◽  
Interfacial Tension ◽  
Crude Oil ◽  
Oil Recovery ◽  
Water Injection ◽  
Spontaneous Imbibition ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Salinity Water ◽  
Low Salinity Water Injection

Low salinity water injection has been frequently studied as an enhanced oil recovery process (EOR), mainly due to promising experimental results and because operational needs are not very different from those of the conventional water injection. However, there is no agreement on the mechanisms involved in increasing the displacement of crude oil, except for the effects of wettability changes. Water injection is the oil recovery method mostly used, and considering the characteristics of Colombian oil fields, this study analyses the effect of modifying the ionic composition of the waters involved in the process, starting from the concept of ionic strength (IS) in sandstone type rocks. The experimental plan for this research includes the evaluation of spontaneous imbibition (SI), contact angles, and displacement efficiencies in Berea core plugs. Interfacial tension and pH measurements were also carried out. The initial scenario consists in formation water (FW), with a total concentration of 9,800 ppm (TDS) (IS ~ 0.17) and a 27 °API crude oil. Magnesium and Calcium brine were also used in a first approach to assess the effect of the divalent ions. Displacement efficiency tests are performed using IS of 0.17, 0.08, and 0.05, as secondary and tertiary oil recovery and the recovery of oil increases in both scenarios. Spontaneous imbibition curves and contact angle measurements show variations as a function of the ionic strength, validating the displacement efficiencies. Interfacial tension and pH collected data evidence that fluid/fluid interactions occur due to ionic strength modifications. However, as per the conditions of this research, fluid/fluid mechanisms are not as determining as fluid/rock.

Role of Kaolinite Clay Minerals in Enhanced Oil Recovery by Low Salinity Water Injection

2018 ◽  
Vol 32 (7) ◽  
pp. 7374-7382 ◽  
Author(s):  
Tina Puntervold ◽  
Aleksandr Mamonov ◽  
Zahra Aghaeifar ◽  
Gunvor Oline Frafjord ◽  
Gyrid Marie Moldestad ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Water Injection ◽  
Kaolinite Clay ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Salinity Water ◽  
Low Salinity Water Injection

The Decisive Role of Microdispersion Formation in Improved Oil Recovery by Low-Salinity-Water Injection in Sandstone Formations

SPE Journal ◽  
2019 ◽  
Vol 24 (06) ◽  
pp. 2859-2873 ◽  
Author(s):  
Pedram Mahzari ◽  
Mehran Sohrabi ◽  
Juliana M. Façanha
Keyword(s):  
Crude Oil ◽  
Oil Recovery ◽  
High Salinity ◽  
Quartz Substrate ◽  
Water Injection ◽  
Improved Oil Recovery ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Salinity Water ◽  
Low Salinity Water Injection

Summary Efficiency of low–salinity–water injection primarily depends on oil/brine/rock interactions. Microdispersion formation (as the dominant interfacial interaction between oil and low–salinity water) is one of the mechanisms proposed for the reported additional oil recovery by low–salinity–water injection. Using similar rock and brines, here in this work, different crude–oil samples were selected to examine the relationship between crude–oil potency to form microdispersions and improved oil recovery (IOR) by low–salinity–water injection in sandstone cores. First, the potential of the crude–oil samples to form microdispersions was measured; next, coreflood tests were performed to evaluate the performance of low–salinity–water injection in tertiary mode. Sandstone core plugs taken from a whole reservoir core were used for the experiments. The tests started with spontaneous imbibition followed by forced imbibition of high–salinity brine. Low–salinity brine was then injected in tertiary mode. The oil–recovery profiles and compositions of the produced brine were measured to investigate the IOR benefits as well as the geochemical interactions. The results demonstrate that the ratio of the microdispersion quantity to bond water is the main factor controlling the effectiveness of low–salinity–water injection. In general, a monotonic trend was observed between incremental oil recovery and the microdispersion ratio of the different crude–oil samples. In addition, it can be inferred from the results that geochemical interactions (pH and ionic interactions) would be mainly controlled by the rock's initial wettability, and also that these processes could not affect the additional oil recovery by low-salinity-water injection. To further verify the observations of geochemical interactions, a novel experiment was designed and performed on a quartz substrate to investigate the ionic interactions on the film of water between an oil droplet and a flat quartz substrate, when the high–salinity brine was replaced with the low–salinity brine. The results of the flat–substrate test indicated that the water film beneath the oil could not interact with the surrounding brine, which is in line with the results of the core tests.

A Fundamental Model for Predicting Oil Recovery Due to Low Salinity Water Injection in Carbonate Rocks

2014 ◽  
Author(s):  
E. W. Al-Shalabi ◽  
K.. Sepehrnoori ◽  
G.. Pope ◽  
K.. Mohanty
Keyword(s):  
Oil Recovery ◽  
Carbonate Rocks ◽  
Water Injection ◽  
Wettability Alteration ◽  
Low Salinity ◽  
Fundamental Model ◽  
Low Salinity Water ◽  
Proposed Model ◽  
Salinity Water ◽  
Low Salinity Water Injection

Abstract The low salinity water injection (LSWI) technique is gaining popularity due to the simplicity of the method compared to other thermal and chemical EOR techniques. In this paper, a fundamental model is proposed which captures the effect of LSWI on improving the microscopic displacement efficiency from carbonates through the trapping number. The proposed model was used to history match recently published corefloods using the UTCHEM simulator. The proposed model incorporates wettability alteration effect through contact angle and trapping parameter. Results showed that history matching of the corefloods was performed successfully using the proposed model. Moreover, wettability alteration is the main contributor to LSWI effect on oil recovery from carbonate rocks. The proposed model was further validated upon which the applicability is extended to include weakly-oil-wet to mixed-wet rocks. This model can be used for oil recovery predictions from carbonate rocks at the field-scale.

Experimental Investigation of the Impact of Crude Oil and Rock on Improved Recovery by Low Salinity Water Injection

2021 ◽  
Author(s):  
Mohamed Alhammadi ◽  
Shehadeh Masalmeh Masalmeh ◽  
Budoor Al-Shehhi ◽  
Mehran Sohrabi ◽  
Amir Farzaneh
Keyword(s):  
Crude Oil ◽  
Oil Recovery ◽  
Water Injection ◽  
Core Sample ◽  
Reservoir Rock ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Reservoir Conditions ◽  
Salinity Water ◽  
Low Salinity Water Injection

Abstract This study aims to compare the roles of rock and crude oil in improving recovery by low salinity water injection (LSWI) and, particularly, to explore the significance of micro-dispersion formation in LSWI performance. Core samples and crude oil were taken from two carbonate reservoirs (A and B) in Abu Dhabi. The oil samples were selected such that one of them would form micro-dispersion when in contact with low salinity brine while the other would not. A series of coreflood experiments was performed in secondary and tertiary modes under reservoir conditions. First, a core sample from reservoir A was initialized and aged with crude oil from reservoir A and a core sample from reservoir B was initialized and aged with crude oil from reservoir B. The cores were then swapped, and the performance of low salinity injection was tested using rock from reservoir A and crude from reservoir B, and vice versa. For the first set of experiments, we found that the crude oil sample capable of forming micro-dispersion (we call this oil "positive", from reservoir A) resulted in extra oil recovery in both secondary and tertiary LSWI modes, compared to high salinity flooding. Moreover, in the secondary LSWI mode we observed significant acceleration of oil production, with higher ultimate oil recovery (12.5%) compared to tertiary mode (6.5%). To ensure repeatability, the tertiary experiment was repeated, and the results were reproduced. The core flood test performed using "negative" crude oil that did not form micro-dispersion (from reservoir B) showed no improvement in oil recovery compared to high salinity waterflooding. In the "cross-over" experiments (when cores were swapped), the positive crude oil showed a similar improvement in oil recovery and the negative crude oil showed no improvement in oil recovery even though each of them was used with a core sample from the other reservoir. These results suggest that it is the properties of crude oil rather than the rock that play the greater role in oil recovery. These results suggest that the ability of crude oil to form micro-dispersion when contacted with low salinity water is an important factor in determining whether low salinity injection will lead to extra oil recovery during both secondary and tertiary LSWI. The pH and ionic composition of the core effluent were measured for all experiments and were unaffected by the combination of core and oil used in each experiment. This work provides new experimental evidence regarding real reservoir rock and oil under reservoir conditions. The novel crossover approach in which crude oil from one reservoir was tested in another reservoir rock was helpful for understanding the relative roles of crude oil and rock in the low salinity water mechanism. Our approach suggests a simple, rapid and low-cost methodology for screening target reservoirs for LSWI.

Novel Insights into Mechanisms of Oil Recovery by Low Salinity Water Injection

2015 ◽  
Author(s):  
M. Sohrabi ◽  
P. Mahzari ◽  
S. A. Farzaneh ◽  
J. R. Mills ◽  
P. Tsolis ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Water Injection ◽  
Low Salinity ◽  
Low Salinity Water ◽  
Salinity Water ◽  
Low Salinity Water Injection
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