Treatment of drilling fluid contamination by carbonate and bicarbonate in deep drilling

The performance features of drilling fluid contaminated by carbonate and bicarbonate in deep well drilling were described and the treatment method to different contamination level was proposed. In view of easy collapse shale at the lower part of the Mesozoic strata, mudstone and coal-bearing strata lines, simply increasing the pH value and using CaO can't satisfy the need of down hole, the application of silicate treatment was proposed. The laboratory experiments and field applications have proved that the use of silicate can not only deal with pollution of carbonate and bicarbonate, but also play an effective role in preventing collapse, which ensure that drilling fluid has a good ability of rheology behavior and anti-collapse.