Impact of Nano-Bentonite in Water-Based Mud (WBM) on Reservoir Formation Damage

Drilling operations often cause formation damage around the wellbore which leads to productivity impairment and high skin factor. The main factors of formation damage are mud filtrate loss and spurt loss due to poor quality mud cake. Interaction between mud filtrate and formation results in severe damage such as clay swelling which causes wellbore instability. Conventional macro and micro based drilling fluids are unable to fulfill certain functional tasks in the increasingly challenging drilling and production environment. Nanotechnology has come to the forefront of research in the past decade with numerous applications in various tindustries. Nano-particles are expected to offer better solutions in preventing formation damage and drilling related issues due to their enhanced physical, mechanical, chemical, thermal and environmental characteristics. Therefore, this project investigates the applicability of nano-bentonite as drilling mud additive in water based mud (WBM) and its impact on formation damage and overall drilling operation.
This paper describes the formulation and preliminary test results of several nano-based drilling fluids starting with the production of nano-particle size bentonite through mechanical grinding using planetary ball mill. The nano-based drilling fluids were formulated using a blend of nano-bentonite and several mud additives to study the rheological and filtration properties and evaluate its suitability for oil and gas field application. Initial mud formulation without the use any mud additives showed lower performance in term of mud rheology. Different combinations of nano-bentonite and mud additives were then tested to obtain the desirable rheological and filtration properties along with the gelling behavior and mud cake quality. The experiments showed that nano-based drilling fluids are able to reduce the mud spurt and filtrate loss with the deposition of thin, well dispersed and effective mud cake. Therefore, these muds could be adopted and used in drilling operations in normal formations to reduce formation damage and drilling related problems.