In the research made below, write 3 more pages, use related to the topic: low water salinity injection and how can it improve the recovery and why.
Keep the lanhuage used in the paper, use sources of SPE ( society of petroleum engineers) on low water salinity injection, and state the things that increase the recovery of oil and what do researchers think.
Introduction and background:
The mechanism behind LWS flooding and its impacts on hydrocarbon recovery are not known yet. It is very crucial to understand more about the interaction between the fluid and the reservoir to optimize the production of hydrocarbons. Having that said, reports emphasize that there are Phenomena, such as wettability alterations (6), surface tension (2,5) and permeability reduction (4).
Gap in knowledge:
There are many questions asked about the behavior of the reservoir when it interacts with LWS flooding. Nowadays, there are no equations that relates the salinity of the water with the production. its needed to have equations and models to predict the production (1).
Surface Tension:
laboratory measurements, showed that there are physical reactions in between the oil/water contact which shows a unique trend. That’s due to that there are some compounds of oil that are surface active with low saline water (brine). There are dispersions which were made in an experiment when crude oil interacts with LWS
This behavior was shown when only LWS water is injected into crude oil, and many different crude oils with different compositions were tested. The test results were showing that only LWS had such a phenomenon of dispersion. This impact can help us to understand the kinetics of crude oil when it interacts with LWS (brine) (2,5).
Fluid and rock interactions and Wettability:
Its showing that there is alteration of the wettability with the addition of the low salinity water. The enhancements of LSF are active especially in sandstone which is very rich of clay. The phenomenon which was accepted is that rock wettability is effectivity shifting from oil wet reservoir to less oil wetting state, which is one possible reason of increasing the oil recovery. After doing two tests, Amott imbibition test and core flooding experiments. Tests illustrated that there were alterations on both capillary imbibition and relative permeability. However, they are indirect. Some model systems were investigated by Lebedeva et al, Lebedeva and fogden. They observed that when decreasing the brine salinity or pH kaolinite becomes more water wet. On the other hand, when the salinity increases, oil adhesion to kaolinite increases as well. For the clay minerals, it shows a behavior that the face and the edges of clay were exposed to both brine and oil. This relates the interaction between the charges and their effect on the wettability. Clay, which is dominant with a negative charge, generates surface charge heterogeneity which would be an influence of the adhesion of oil to clay. A discerption of figures of how high and low salinity water injection on different time affects the wettability and capillary differences (6).
Permeability reduction:
There are studies which was made by Morrow et and tang in 1997 and 1999, that show that the recovery increases when the clay interaction is weakening in the porous medium after the addition of low water salinity after adding it on clayey sandstone. They consider that some of the clay are produced and the clay that is going to be produced has absorbed oil which will lead to the permeability reduction; however, increase in the hydrocarbon recovery. (4)
Current understanding:
As we discussed, With low water salinity injection. It shows a trend of increased oil recovery. Different phenomena were discovered which would help to understand more about the idea behind the salinity and its effect on the recovery. There were studies which were made as a field scale in northeastern Wyoming for water flooding which was made by The Idaho National Laboratory (INL) which shows the hydrocarbon recovery with change of the salinity of water. In addition, when these studies were made, they have found ambiguous behavior. Such as, after the injection of salt water of 13 years, the salt concentration decreased from 60,000 to 15,500 ppm in Westemlek. Below, there are graphs which shows how does the salt concertation affect the recovery (3,4).
According to Li (7), the studies have been done shows that the most lithology which gets affected to the effect of low water salinity injection is sandstone which has some clay saturated with asphaltic crude oil. Meeting this condition, about 5% more of the pore space would be produced close to the wellbore region. And he said that wettability alteration, permeability reduction and the emulsion formation are the causes. He also said that the studies that they made, is that the most important phenomena which made the production higher is the permeability reduction by the migration of clay minerals. However, he also said that at the maximum permitted pressure, the production of would be the same for both LWS and brine injection. However, the increased production is due to the increase of both the velocity and the acceleration.
Another research was made by university of Wyoming (8), it showed that the LWS injection had a very good impact and it increased both the gas and oil permeability’s with higher production of 16% of OOIP, and that is due to the alteration of the wettability. The test was made in poorly sorted and cemented kaolinite.
For low and high salinity injection, there was a test made by university of Tulsa (9) and the test was log inject log test. They noticed that, the most prominent effects are the permeability reduction and also the wettability alteration associated with the LWS. The characterization of LWS concentration they given is (<4000 ppm)
References:
1. “EOR Performance and Modeling” WWW.Energy4me.org, JPT (Jan, 2009)
2. “Visualizing Low-Salinity Waterflooding” Colin Sanderson, ITF, and Mehran Sohrabi, SPE, Heriot-Watt University, (November 2014)
3. “Low Salinity and Engineered Water Injection for Sandstone and Carbonate”. By Emad Walid Al Shalabi, Kamy Sepehrnoor. N.R. 1997.
4. “Low Salinity Oil Recovery on Clayey Sandstone: Experimental Study” M. Cissokho2, S. Boussour3, P. Cordier4, H. Bertin2, and G. Hamon5. (OCTOBER 2010)
5. “Crude Oil/Brine Interactions and Spontaneous Formation of MicroDispersions in Low Salinity Water Injection”. By Mahzari and Mehran Sohrabi. SPE, (April 2014)
6. Mahani, Berg, Ilic, Bartels, & Joekar-Niasar. (2015). Kinetics of Low-Salinity-Flooding Effect. Socity of Petroleum Engineering, 9-11.
7. “Oil Recovery by Low Salinity Water Injection into a Reservoir: A New Study of Tertiary Oil Recovery Mechanism ” Y. Li. (24 June 2011).
8. ” LOW SALINITY WATERFLOODING OF A RESERVOIR ROCK”. University of Wyoming. Nina, Xina, Yin and Morrow. (September, 2007)
9. ” Webb, K.J., C.J.J. Black and H. Al-Ajeel.: “Low salinity oil recovery – log-inject- log” SPE 89379 in proceedings of SPE/DOE Fourteenth Symposium on Improved Oil Recovery, Tulsa, Oklahoma, April, 2004.
