A novel technique for the modeling of shale swelling behavior in water-based drilling fluids

Abstract

One of the most significant problems in oil and gas sector is the swelling of shale when it comes in contact with water. The migration of hydrogen ions (H+) from the water-based drilling fluid into the platelets of shale formation causes it to swell, which eventually increases the size of the shale sample and makes it structure weak. This contact results in the wellbore instability problem that ultimately reduces the integrity of a wellbore. In this study, the swelling of a shale formation was modeled using the potential of first order kinetic equation. Later, to minimize its shortcoming, a new proposed model was formulated. The new model is based on developing a third degree polynomial equation that is used to model the swelling percentages obtained through linear dynamic swell meter experiment performed on a shale formation when it comes in contact with a drilling fluid. These percentages indicate the hourly change in sample size during the contact. The variables of polynomial equation are dependent on the time of contact between the mud and the shale sample, temperature of the environment, clay content in shale and experimental swelling percentages. Furthermore, the equation also comprises of adjustable parameters that are fine-tuned in such a way that the polynomial function is best fitted to the experimental datasets. The MAE (mean absolute error) of the present model, namely Scaling swelling equation was found to be 2.75%, and the results indicate that the Scaling Swelling equation has the better performance than the first order kinetics in terms of swelling predication. Moreover, the proposed model equation is also helpful in predicting the swelling onset time when the mud and shale comes in direct contact with each other. In both the cases, the percentage deviation in predicting the swelling initiation time is close to 10%. This information will be extremely helpful in forecasting the swelling tendency of shale sample in a particular mud. Also, it helps in validating the experimental results obtained from linear dynamic swell meter.

An Experimental Study and Machine Learning Modeling of Shale Swelling in Extended Reach Wells When Exposed to Diverse Water-Based Drilling Fluids

“…The primary objective of extended reach wells is to access remote or hard-to-reach hydrocarbon reserves while minimizing the number of surface locations and drilling costs. , One of the significant challenges associated with extended reach wells is the risk of shale swelling when exposed to different water-based drilling fluids (WBDFs) . Shale swelling occurs when the shale formations encounter WBDFs, leading to the expansion and deformation of the shale rocks. − Shale is composed of clay minerals, which can absorb water and expand. − The interaction between shale and drilling fluids can have far-reaching consequences, including wellbore instability, formation damage, lost circulation, and decreased drilling efficiency. − …”

“…Their model aimed to capture the influence of shale mineralogy and fluid composition on shale swelling. Lalji et al developed a model that utilizes a multiple degree’s polynomial function to estimate the linear swelling. Ibrahim and Elkatatny , used ML techniques to predict the contact angle of shale, which is an indirect indication of shale wettability and swelling.…”

Application of Hydrothermal Synthesized Titanium Dioxide-Doped Multiwalled Carbon Nanotubes on Filtration Properties─Response Surface Methodology Study

“…Drilling muds are mainly used to clean the wellbore by lifting the drilled cutting out of the borehole, keep the drill bit cool and lubricated, maintain the integrity of the borehole, and assist during wireline operations. , In general, drilling fluids are characterized into three main streams, namely; water-based mud (WBM), oil-based mud (OBM), and synthetic-based mud (SBM) . The SBM and OBM are more effective than WBM in terms of shale stability, rheological and filtration behavior, and high wellbore stability. , Nevertheless, factors like mud formulation, cost, and disposal are some major concerns that have severely impacted their use in the petroleum industry . Therefore, WBM remains the most preferred option in drilling despite some deficiencies, especially in the form of shale swelling.…”

A Novel Ascorbic Acid Based Natural Deep Eutectic Solvent as a Drilling Mud Additive for Shale Stabilization

“…Shale swelling inhibitors are chemicals that are added to drilling fluids to prevent the swelling and expansion of shale formations when drilling for oil and gas [11]. This can help to maintain the stability of the wellbore and prevent damage to the surrounding rock.…”