In a silicate drilling fluid system, the surface pores of clay particles are easily blocked by silicate and their surface characteristics are highly changed by ion adsorption, which will increase the probability of adhesion between cutting particles during the drilling fluid circulation. Bit balling will arise from the interaction between aggregation of cutting particles and the bit surface, which is not conducive for the safe and economic drilling operation. In this work, a new type of lubricant (AEC-N) with anti-bit balling performance was synthesized by using dodecyl alcohol polyoxyethylene ether carboxylate (AEC), thionyl chloride (SOCl2), and N,N-dimethyl-1,3-propanediamine as raw materials. Experimental results showed that AEC-N had little effect on the rheological properties of silicate drilling fluid. And it can significantly improve the lubricity and filtration properties of silicate drilling fluid. Lubricant molecules can firmly adsorb onto silicate minerals and metal surface to prevent cuttings from coalescing into each other and bonding with drilling tools. Comparison of lubrication coefficient gave 0.082 for silicate drilling fluid with 2 wt% AEC-N and 0.181 for silicate drilling fluid without AEC-N, indicating that AEC-N can effectively reduce drilling friction and the risks of wellbore instability. The steel ball and artificial water-bearing cuttings were added to silicate drilling fluid to evaluate the anti-bit balling performance of the lubricant by the presence of bit balling, in combination with the process of downhole bit balling formation. When the addition of AEC-N to silicate drilling fluid was 2 wt%, there was no mud packing on the surface of steel balls under the condition of 10 wt% artificial water-bearing cuttings, indicating that AEC-N had a good anti-bit balling performance.
