Fast drilling technologies for deep wells in Oil Province G of Colombia

The deep well drilling in Gigante oil province in the mountainous area of Columbia is extraordinarily complex. There are problems such as severe inclination within the piedmont structure, downhole troubles caused by several sets of pressure systems, the wide range of brittle shale collapse caused by severe lost circulation and the collapse due to high density drilling fluid caused by micro cracks, wellbore collapse caused by the under-compacted thick mudstone, illite smectite mixed layer and the tectonic stress, and drill plpe sticking caused by soft-hard cross formations. There are also problems such as wellbore unstability caused by geostress and fracture belts and severe leakage, anomalous geothermal gradient(up to 42 °C/1 000 m), Thus it is extremely difficult to perform drilling operatios because of severe lost circulation, collapse, stuckpipe and blowout. In view of the troubles encountered in deep well drilling in this oil province, this paper has analyzed the geologic origin and characteristics of this block, depicts the main factors which affect the drilling rate of deep wells and presents the solutions and suggestions, which have great significance in improving deep well drilling rates，reducing drilling costs and drilling cycle and accelerating the exploration & developing rate of the entire block.