Abstract:
Shale formation plays a significant role for the discovery of hydrocarbon resources,
especially in unconventional oil and gas reservoirs for its larger volume of reserves.
However, the presence of shale can create numerous challenges due to its complex behavior
in terms of drilling with WBDF. Shale has a low permeability. To increase the permeability,
the hydraulic fracturing technique is used. When the water-based drilling fluid come in
contact with the shale formation, the ion exchange is responsible for the swelling of the
clay mineral. Smectite group member (Montmorillonite) can exhibit this type of behaviors.
Increase of interlayer space causes the shale to swell significantly. This is caused due to the
adsorption of water on the surface of clay layers. This study's objectives are to select a
potential inhabiting agent to reduce the swelling of clay by using the molecular dynamic
simulation and to measure the interlayer spacing between the layers. All simulations are
done in this study using the BIOVIA MATERIAL STUDIO 2020. Molecular dynamic
simulation provides insights into the atomic-scale processes involved in clay swelling. At
first, the Na-MMT model has been created by giving their specific parameters and then the
adsorption simulation was done by the Monte Carlo simulation. Where in a 2% Potassium
Chloride (KCl) solution, 1 KCl molecule replaces 68 water molecules. Thus, the ratio of
KCl and water molecule was 1:210. Using the lowest energy geometry optimized model
dynamics simulation was performed. If the number of water molecules are increased, the
basal spacing is also increased. Thus, the hydrational forces also increases in the same way.
As the amount of KCl adsorption increases the amount of water adsorption decreases. After
adding the selective inhibitor (KCl), the basal spacing has been decreased than before and
increases the swelling reduction ratio as well. This study reviews the swelling problem of
MMT, its proper inhibiting agent to reduce the swelling of the shale in the petroleum
industry and the changes of the interlayer spaces between the shale formations by using the
molecular dynamic simulation.
