Experimental investigation of water composition and salinity effect on the oil recovery in carbonate reservoirs

Water injection has been known as a conventional approach employed for years in order to achieve higher oil recovery from oil reservoirs. Since the last decade many researchers conducted on the water injection assessment suggested that low salinity water flooding can be an effective flooding mechanism and it can be used as an enhanced oil recovery method. Several examinations were conducted to identify governing mechanisms entailed in oil extraction and the effect of salinity and different types of ionic contents contained in Formation Water (FW) and injected fluid. This study is dedicated to address the influence of salinity and different types of ionic contents contained in formation water and injected fluid on incremental oil recovery. For this purpose, fluid–fluid and rock–fluid interaction were investigated especially for evaluating the effect of calcium ions in the formation water and sulfate ions in the injected water. Several experiments were carried out including core-flooding, contact angle, and imbibition tests. While former researchers concluded that reducing the salinity of injected water causing a decrease in ionic strength may lead to a greater oil recovery, in this research, we showed that these statements are not necessarily true. It was observed that existence of the high calcium concentration in the formation water would cause significant effect on wettability status of rocks and final oil recovery during low salinity water injection. This process is mainly due to rock wettability alteration. Wettability alteration mechanism in carbonate rocks is explained through interaction between rock and fluid composition. The results indicate the decisive role of calcium ions in the formation water at all stages from aging in oil to primary and secondary recovery. In addition to that, it was observed that more sulfate ion concentration in the injected water enhances rock wettability alteration.

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Enhanced Oil Recovery using Smart Water Injection

Journal of Engineering ◽

10.31026/j.eng.2018.08.04 ◽

2018 ◽

Vol 24 (8) ◽

pp. 40

Author(s):

Hussain Ali Baker ◽

Kareem A. Alwan ◽

Saher Faris Fadhil

Keyword(s):

Oil Recovery ◽

Water Injection ◽

Deionized Water ◽

Water Flooding ◽

Wettability Alteration ◽

Formation Water ◽

Low Salinity ◽

Smart Water ◽

Low Salinity Water ◽

Salinity Water

Smart water flooding (low salinity water flooding) was mainly invested in a sandstone reservoir. The main reasons for using low salinity water flooding are; to improve oil recovery and to give a support for the reservoir pressure. In this study, two core plugs of sandstone were used with different permeability from south of Iraq to explain the effect of water injection with different ions concentration on the oil recovery. Water types that have been used are formation water, seawater, modified low salinity water, and deionized water. The effects of water salinity, the flow rate of water injected, and the permeability of core plugs have been studied in order to summarize the best conditions of low salinity water flooding. The result of this experimental work shows that the water without any free ions (deionized water) and modified low salinity water have improved better oil recovery than the formation water and seawater as a secondary oil process. The increase in oil recovery factor related to the wettability alteration during low salinity water flooding which causes a decrease in the interfacial tension between the crude oil in porous media and the surface of reservoir rocks. As well as the dissolution of minerals such as calcite Ca+2 was observed in this work, which causes an increase in the pH value. All these factors led to change the wettability of rock to be more water-wet, so the oil recovery can be increased.

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

10.2118/spe-169911-ms ◽

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.

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Optimum Salt Concentration Design of Low Salinity Water Injection in Tangai Structure at Sukananti Field

10.29118/ipa21-e-51 ◽

2021 ◽

Author(s):

H. Zakyan

Keyword(s):

Oil Recovery ◽

Salt Concentration ◽

Water Injection ◽

Production Performance ◽

Formation Water ◽

Low Salinity ◽

Low Salinity Water ◽

Salinity Water ◽

Low Salinity Water Injection ◽

Optimum Salt Concentration

Enhanced Oil Recovery (EOR) come up with promising result to endure mature fields production performance and has been proven worldwide in many various methods. Recently, Low Salinity Water Injection evolves as a simply operation and relatively low cost EOR method with wide of research and implementation seem to be proved effective in the past decades. Some laboratory tests have indicated that injecting low salinity water can improve conventional waterflood performance by 5 – 20%. Hence, it introduces a promising idea that Low Salinity Water Injection should be implemented to mature fields in Indonesia for EOR activity. This paper will focus on determining the optimum salt concentration of injection water for low salinity water injection. Low salinity water injection in this study will be acted as a secondary recovery method. The production performance as a result of low salinity water injection was acquired by numerical simulation using tNavigatorTM Simulator. This simulation will be conducted in Tangai Structure at Sukananti Field, South Sumatera Basin, Indonesia with Talang Akar Formation reservoir target. The simulation is conduct with the constraint injection rate of 1,340 BWIPD. The low salinity water is designed by dilution of salt concentration from formation water with 18,000 ppm of concentration. In this case, the sensitivity of low salinity water, mainly amount of salt concentration design, will be conducted in the simulation consisting of using formation water as scenario’s base case and various low salinity water designs which will be limited until 10x of dilution (1,800 ppm). The result of this study concluded that Low Salinity Water Injection achieved more oil recovery than conventional waterflood did. This incremental is caused by wettability alteration due to of salt concentration changes which attract the clay minerals in reservoir through many complex mechanisms. The simulation result shows that injection water with 10x dilution (1,800 ppm) is chosen as an optimum salt concentration design, which gives the best result with gains additional oil recovery and recovery factor about of 118,8 MSTB and 4,9% respectively from a scenario by injecting formation water (18,000 ppm).

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Effect of divalent cations in formation water on wettability alteration during low salinity water flooding in sandstone reservoirs: Oil recovery analyses, surface reactivity tests, contact angle, and spontaneous imbibition experiments

Journal of Molecular Liquids ◽

10.1016/j.molliq.2018.11.093 ◽

2019 ◽

Vol 275 ◽

pp. 163-172 ◽

Cited By ~ 23

Author(s):

Hasan N. Al-Saedi ◽

Ralph E. Flori ◽

Patrick V. Brady

Keyword(s):

Oil Recovery ◽

Divalent Cations ◽

Surface Reactivity ◽

Spontaneous Imbibition ◽

Water Flooding ◽

Wettability Alteration ◽

Formation Water ◽

Low Salinity ◽

Low Salinity Water ◽

Salinity Water

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

SPE Journal ◽

10.2118/172778-pa ◽

2016 ◽

Vol 22 (02) ◽

pp. 407-416 ◽

Cited By ~ 42

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.

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