Application of alkali treatment for sticking in Well WBD-1

Abstract:

When the drill string is pressed against the wellbore due to poor mud cake quality， it is prone to sticking under the pressure difference between the drilling fluid column pressure and the formation pressure， which poses a challenge to subsequent drilling construction. In this paper， the mechanism of releasing filter cake in low solid drilling fluid system based on bentonite is analyzed， and the dissolution of filter cake in different concentrations of sodium hydroxide solution is discussed through experiments. The results show that the combination of OH^- with Ca²⁺ and Mg²⁺ increases with time and the 6% sodium hydroxide solution has the better effect on filter cake under the same condition. The application in Well WBD-1 shows that compared with acid soaking and oil soaking， the treatment time of foam alkali is faster， which can avoid larger downhole complexity， reduce the interference to the subsequent drilling fluid and save the drilling cost. The results have a reference value for the similar sticking processing.

Key words:sticking;wellbore instability;pyroalkali pipe-freeing agent;sticking release;Well WBD-1;oil and gas geological survey