摘要
Most of water based drilling fluids easily penetrate into shale formations and cause serious problems such as well instability,destruction of the formation,wall pipe folding and pipe adhesion.The present research aims to assess the effects of alumina nano-particles(alpha and gamma)on shale/clay stability due to the unique specifications of alumina(alpha and gamma)nano particles.The SEM,XRD,EDAX and AFM analyses of recovered shale samples indicate that the average size of alpha alumina nano-particles coating the shale surface and the pores existing in the shale is between 25 and 35 nm,whereas the average size of gamma alumina nano-particles coating the shale surface and the pores present in the shale is between 20 and 30 nm.In addition,samples recovered by nano-alpha reveal more porosity remained in the shale sample in comparison with the nano-gamma nano-sample.Furthermore,the results obtained from EDAX illustrate a suitable nano-gamma alumina over the recovered shale.The experiment with five types of drilling fluid without the presence of potassium chloride as an inhibitor salt designed.Thus,the water based drilling fluid containing nano-gamma alumina with less than 1%wt was chosen as the best sample.Generally,the presence of alumina nano-particles optimizes the stability of formations containing ions like shale.
