The Application of Ultra High Density Drilling Fluids in Complex Deep Wells in the Amu Darya Right Bank Gas Field, Turkmenistan

The thick gypsum salt formation (with thickness of 700-1000 m) in the Kimmeridgian in Upper Jurassic of the Amu Darya Right Bank Gas Field has typical abnormal high pressures, there is a risk of high pressure salt water invasion in the process of drilling. For that reason, the density of drilling fluid needs to be 2.48 kg/L, and otherwise it could not meet the needs of safe and fast drilling by conventional drilling fluids. On the basis of existing saturated brine drilling fluids, the treatment agents with excellent resistance to high temperatures and pollution of gypsum and salt have been optimized. Combined with other agents, ultra high density saturated brine drilling fluids have been developed. Indoor performance tests showed that the drilling fluids could have a density up to 2.48 kg/L, and possess excellent high-temperature stability, better lubrication, higher shale resistance and anti-pollution capacities. Field application results in more than 30 wells showed that the newly developed drilling fluids could successfully eliminate salt formation creep, and solve the problem of drilling fluid pollution and the invasion of high-pressure salt water during drilling in a long gypsum salt formation interval. These drilling fluids can significantly enhance the ROP and shorten the drilling cycle.