Synthesis and Experimental Investigation of Non-damaging Drilling Fluid Using Biodegradable Additives for Shale Stability

Objective of this work is to synthesize and develop a non-damaging drilling fluid (NDDF) using minimal amount of biodegradable additives such as turmeric, calcium carbonate (CaCO3), carboxy methyl cellulose (CMC), and psyllium husk which is free from bentonite and barite unlike conventional drilling fluid for drilling of the pay zones without damaging or reacting with the earth subsurface formation. The NDDF mud is prepared using distilled water at various concentrations of psyllium husk, and the rheological properties of the NDDF are determined via marsh funnel, hand crank viscometer, pH meter, mud balance, and Remi stirrer. The rheological properties such as effective viscosity, plastic viscosity, apparent viscosity, gel strength at 10 s and 10 min, mud density, and pH value are determined using the above equipment. All the experiments are done with two rounds to validate the generated data in this work. A shale stability test has also been conducted for 24 h where shale samples have been taken from Assam-Arakan Basin. It has been observed that the prepared NDDF muds show more effective rheology using low concentrations such as 5 and 1 g as compared to high concentrations (25 and 15 g) of psyllium husk. The pH observed is 8.69 for 5 g and 8.96 for 1 g of psyllium husk which helps to prevent corrosion. The shale stability test for 5 g of psyllium husk gives better results than 1 g of psyllium husk where swelling% came less than 20% and spalling% is less than 4% for both the concentrations. It is environment friendly, low cost, accessibility, and its anti-corrosive nature. This work mainly provides insight to use psyllium husk and turmeric based NDDF to protect the weak or unconsolidated formation such as shale formations and to prevent the corrosion to the drilling equipment. This work is mainly focused on using minimal number of biodegradable additives to develop the NDDF as above mentioned. Therefore, it can be used in unconsolidated earth subsurface formations to prevent it from the formation damage which provides shale stability along with the drilling equipment.