Experimental Study of Formulation of Formate based drilling fluid system

Drilling of shale and clay-rich geological formations are always challenging because of their instability and watersensitivity reservoirs cause a high degree of wellbore instability, torque, drag, build up of low gravity solids, bottomhole fill, stuck pipe . Associated problems include formation damage, logging and primary cementation failures,borehole washouts etc. Oil-based drilling fluids (OBDF) are widely used in drilling operations, especially in highlytechnical wells. OBDF systems perform much better than water based drilling fluid (WBDF) in boreholestabilization and they allow faster penetration rates.A formate-based fluid has been successfully used in many HPHT well operations since they introduced in fieldpractice. They have many advantages when compared with conventional HPHT drilling fluids such as: minimalformation damage, maintenance of additive properties at high temperatures, reduced hydraulic flow resistance, lowpotential for differential sticking, etc. Formate-based fluids can be applied during deep slim hole drilling, shaledrilling, and reservoir drilling, salt and gas hydrate formations drilling.The laboratory research was done to determine composition of formate base drilling fluid. It was formulated usingsodium and potassium formate salts, KCL, starch and lime stone. Formate base mud is solid free system. So, mudcake is thin and resilient, it is conductive to improve cementing quality greatly. In these experiments, formate baseddrilling fluids containing two types of format salt (NaF and KF) at different concentrations were tested by a Fan-53viscometer.Experiments show that the formate drilling system has good rheological and lubricate properties and stronginhibition ability. It shows that salt formate improves the thermal stability of polymers.

کلیدواژه ها:

Formate salts ، shale inhibition ، rheological properties ، lubrication property