Several types of organic compounds were tested as rate of penetration (ROP) enhancers for a simple gel/water mud. Experiments conducted in a full-size drilling apparatus with both rollercone and PDC bits at wellbore pressures of 1100 and 2000 psi indicate that a paraffin/ester mixture, several terpenes and a mixture of insoluble poly(proppylene glycols), or PPG's, can all increase the ROP by 5 to 20% when added at levels of 2–4% by volume. Complementary lubricity and shale recovery studies suggest that the paraffin and terpenes function by making the steel surfaces less water-wetting, thereby reducing the tendency of partially hydrated sticky shales to adhere. The PPG mixture, on the other hand, may function primarily by interacting directly with the shales to reduce their tendency to form a sticky mass. In either case, the additives increased ROP to levels comparable to the ROP observed with pure water.