Optimal and Fast Drilling Technology for Shunnan Block

Since the reservoirs are deep and geothermal temperature is abnormally high in Shunnan Block,some drilling problems are related to the deficiencies of drilling fluid performance;problems,such as the wellbore lost stability and the well was easily deviated and so on,caused long drilling time and high drilling cost,have seriously slowed down the progress of exploration and development of the block.Some studies on optimal and fast drilling techniques had been made to solve the problems mentioned above.Based on the geological conditions in Shunnan Block and curves of three formation pressures foreseen,the casing program design had been further optimized.On the basis of analysis of wellbore instability,through a lot of tests,new recipe of drilling fluid was selected to solve high temperature and wellbore sloughing problem.To cope with the problem of hole deviation in Queerquek Formation,BHA of MWD+single bent PDM motor was used for drilling fast,which is cheap and has good function of anti-deviation.To overcome the problem that safe window for mud density adjustment is narrow in gas reservoir and gas kick or losses easily to happen,MPD technique was applied to drill gas reservoir zones.Field applications showed that fast drilling technique could improve the wellbore quality,shorten the drilling time and achieve a safe drilling.This indicated that fast drilling technique was applicable to Shunnan Block,could solve the existing problems of drilling and could provide technical support to the acceleration of exploration and development of the block.