Research Institute of Petroleum Industry Faculty of Research and Development of Oil Upstream Industry Petroleum Engineering Department Tehran, Iran Monitoring Wettability Alteration of Porous Media by Silica Nanoparticles: An Experimental Approach by: Saber Mohammadi November 2015

Outlines Introduction 1 Approach & Organization 2 Results & Discussions 3 Concluding Remarks 4

Nanotechnology & Solution to Upstream Oil Industry Challenges Introduction Exploration IOR/EOR Production Drilling Reservoir Management Nanotechnology & Solution to Upstream Oil Industry Challenges

Introduction Motivation: Increasing of world demand for energy requires the increase in production of crude oil through different EOR scenarios. The feasibility of these scenarios depends on many factors such as flow mechanisms in porous media and properties of porous medium at microscopic/macroscopic levels. An important part of these methods is related to the wettability of the reservoir rock. Understanding the porous media wettability is crucial for well planning and optimizing EOR scenarios. Wettability alteration is one of the most important methods for oil recovery from sandstone and carbonated reservoirs. Despite the extensive literature about the effect of wettability on microscopic displacements of fluid flow, pore-scale visualization of the role of “silica nanoparticles” on wettability of the reservoir rock has not been well addressed.

Wettability Alteration Methods Introduction Wettability Alteration Methods Thermal Methods hot water steam injection Chemical Methods surfactant nano materials

Introduction Nanotechnology & Wettability Alteration: The use of nanotechnology has recently gained momentum in the oil and gas industry for its potential applications in EOR processes. In recent years, attention has been drawn to the effect of nanoparticles on the wetting behavior of reservoir rocks. Wettability alteration by nanoparticles is due to their adsorption on rock surface and forming a water-wet layer on it; thus the viscous forces required to overcome capillary forces are reduced dramatically. Illustration of wedge-film at the base of the drop due to disjoining pressure (Wasan et al., 2011)

Introduction Characteristics and Properties of Silica Nanoparticles (SNPs) : SNPs are water-soluble, non-toxic, odorless particles that can easily be fabricated and modified at low cost. SNPs are characterized by their very low bulk density, about 0,04 – 0,1 g/cm3, and a high specific surface area, typically 200 – 300 m2/g. SNPs can move freely through the porous media due to the small size of nanoparticles. SNPs have high surface area which lead to an increased tendency of silica nanoparticles to adsorb on the walls of porous media. SNPs have high heat transfer efficiency.

Approach & Organization Goal: assess the effect of hydrophilic silica nanoparticles (SNPs) on wettability of reservoir rock and pore-scale water flooding in one quarter 5-spot glass micro-models at different temperatures and concentration of nanoparticles Methodology: Contact angle measurement were conducted to see how SNPs affect fluid interfaces at a solid surface (oil-water-rock system) Flooding experiments in 5-spot glass micro-models with water flooding & dispersed silica nanoparticles in water (DSNPW)

Approach & Organization Experimental Setup: contact angle measurement contact angle measurement in sessile drop method

Approach & Organization Experimental Setup: micro-model apparatus Schematic diagram of the micro-model setup (Mohammadi et al., 2013a) Picture showing the main components of the micro-model setup

Approach & Organization Why micro-model experiments? Effective and relatively inexpensive tools for visualizing and quantifying complex flow phenomena through the porous media. Fluid displacement and redistribution as well as alteration of wettability can be viewed and monitored. Ability to visualize the fluid dynamics. Utilizing different porous media. Better understanding of displacement processes at pore level. Smaller sample volume in comparison to the core flood experiments.

Approach & Organization Properties of silica nanoparticles TEM image of dispersed silica nanoparticles in water (DSNPW)

Approach & Organization Physical and hydraulic properties of the constructed micro-model Injection Port Production Port schematic of laser-based flow pattern used for flooding experiments (Mohammadi et al., 2013b)

Approach & Organization

Results & Discussions: Contact Angle Measurement Changes in the contact angle of carbonated rock slice aged in heavy crude oil vs. time at 25 oC and 80 oC

Results & Discussions: Contact Angle Measurement Slices of carbonated rock used in this study SEM image of an oil-wet carbonated rock slice before aging in 0.10 %wt DSNPW SEM image of an oil-wet carbonated rock slice after aging in 0.10 %wt DSNPW

Results & Discussions: Contact Angle Measurement T=25 oC T=80 oC Effect of SNP concentrations on contact angle of carbonated rock slices vs. time

Results & Discussions: Contact Angle Measurement Effect of SNP concentrations on contact angle of carbonated rock slices vs. temperature

Results & Discussions: Flooding Experiments Visualization of oil displacement during water flooding

Results & Discussions: Flooding Experiments Visualization of oil displacement during DSNPW (0.5%wt) flooding

Results & Discussions: Flooding Experiments Oil recovery factor vs. pore volume of injected fluids Injected fluid breakthrough time vs. SNP concentrations

Results & Discussions: Flooding Experiments a) b) Pore-scale visualization of media wettability during flooding experiments: a) water flooding, b) DSNPW flooding

Results & Discussions: Flooding Experiments Simple schematic of a sample throat representing permeability reduction due to silica adsorption Permeability of porous media during DSNPW flooding with different weight percent of SNPs

Concluding Remarks This work illustrates the successful application of SNPs for wettability alteration. The hydrophilic nature of selected SNPs, strong hydrogen bonding between silica and water and therefore increment in surface free energy are responsible for wettability alteration from oil-wet to water-wet. Contact angle measurement on slices of carbonated rock showed that changes of contact angle is more intensified by SNPs concentration and temperature. DSNPW flooding in 5-spot glass micro-models results in higher ultimate oil recovery as well as better sweep efficiency in comparison to the water flooding. Increasing the SNPs concentration postpones the breakthrough of injected fluid during flooding experiments in 5-spot glass micro-models. DSNPW flooding in f5-spot glass micro-models results in higher ultimate oil recovery as well as better sweep efficiency in comparison to the water flooding.

Concluding Remarks The distribution of DSNPW solution during flooding tests in pores and throats showed strong water-wet condition after flooding with high concentration of nanosolution. Due to adsorption of SNPs on the glass surface in pores and throats, the wettability alteration by chemical treatment led to an absolute permeability reduction. Results of this work suggest the SNPs as an additive to water for improvement of oil recovery during water flooding instead/before implementation of other suitable EOR schemes.

Selected References Mohammadi, S., Ghazanfari, M. H., Masihi, M. “A pore-level screening study on miscible/immiscible displacements in heterogeneous models”. Journal of Petroleum Science and Engineering. 2013a, 110, 40-54. Mohammadi, S., Maghzi, A., Ghazanfari, M. H., Masihi, M., Mohebbi, A., Kharrat, R. “On the control of glass micromodel characteristics developed by laser technology”. Energy sources, Part A: recovery, utilization, and environmental effects. 2013b, 35(3), 193-201. Wasan, D., Nikolov, A., Kondiparty, K. "The wetting and spreading of nanofluids on solids: Role of the structural disjoining pressure." Current Opinion in Colloid & Interface Science. 2011, 16 (4), 344-349.

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