A Novel Hydrophobically Modified Polyacrylamide as a Sealing Agent in Water-based Drilling Fluid

Abstract

Novel hydrophobically modified polyacrylamide (HMP) copolymers based on octadecyl dimethyl allyl ammonium chloride (C₁₈DMAAC) were synthesized by homogeneous polymerization. The sealing performance of the HMP as sealing agent in drilling fluid was studied. The results showed that HMP-3 containing 0.66% (molar ratio) hydrophobic monomer gave the best sealing property. Compared with the traditional sealing agent, HMP-3/clay could seal the cores of different permeabilities effectively by forming a low-permeability barrier with the help of bridge material. Permeability recovery test indicated that the recovery rate of cores treated by HMP-3 systems was over 90%. The particle size analysis showed that the grain distribution of drilling fluid system can be changed by HMP-3, and the system containing HMP-3 component covered a much wide distribution, so it can be used in a wide range of pore sizes and permeabilities without foreseeing the size of pore throat definitely. This work has provide a new idea to solve the seepage losses of microfractured formations.

Keywords:

• drilling fluid
• hydrophobically modified polyacrylamide
• low permeability
• sealing agent
• sealing capacity