1. Calciumtreated mud it prevent the swelling of formation shale, manage sloughing shale,whole enlargement and also to prevent formation damage.2. Polymermud is used in stabilize the formation and reduce filtrate less.
3. Lowsolid mud help in improving rate of penetration.4. Workover fluid used for acidizing and fracturing operation and in inhibiting swelling formation shale and minimize formationdamage5. Oil orsynthetic fluid is Useful in in hole stabilization, in high temperature wells,deviated holes and pipe sticking problem.6. Mixedmetal hydroxide mud used for stabilization of borehole and protection ofproducing formation, to lower pump resistance and for suspension of solidduring shut down and it improve drilling rate and cutting removal.7.
Oilbased drilling fluid is used to stabilize clay formation and for toleratingsalt formation. In any drilling operations, there mustbe proper and a general planning of the well in order to select the bestdrilling mud to drill well bore. Commonly, criteria for selecting drillingfluid are based on how they should easy to use (performance of drilling fluid),not too expensive and environmentally friendly (like skin irritation andcontact dermatitis). selecting drilling fluid system starts with identifying adrilling fluid family, according to the nature of formation and choice of themud formulation will be the second step, one has to decide on the range ofdesired properties, leading to use a minimum amount of additives, therefore forselection of drilling fluid system for a particular well is based on manyfactors – localpractices and operator performance – density required to control subsurfacepressure and hole size – characteristicsof the formation to be drilled including well bore stability – Supplier rangeof systems and products – Anticipated temperature and pressure – Completion type,health, safety environment (HSE) consideration mixed metal hydroxide drilling fluid havebeen used successfully in horizontal wells, in tunneling under river and road,for drilling in fluids, for drilling large diameter holes, and with coiledtubing.
Non aqueous based drilling fluid used in a particularly remote orenvironmentally sensitive area and commonly preferred option for hightemperature application