Drilling Technology And Field Test Of Directional Well For Drilling In The Large Section Of The Salt-gypsum Layer

Due to the phenomenon of the creep exists in salt gypsum layer, it is easy to cause instabilityof borehole, shrinkage hole sticking, collapse hole sticking, adhesion hole sticking and hole leakage problems, so it is risk for well drilling in the alt gypsum layer. In this paper, through the comprehensive analysis of the gypsum formation, lithologyof the Uzbek KC, taking KC100 bis as an example, from the aspects of drilling fluid technology, well structure design, tool and BHA, trajectory design and engineering measures, a detailed analysis of the design, we find a drilling technical solution for the thick salt gypsum layer in this area. It mainly includes the following 5 aspects:In the performance of drilling fluid, the drilling fluid density is not only used to inhibit the creep of salt and gypsum layers, but alsoused to keep the borehole stability. Use theundersaturated salt water drilling fluid drilling salt gypsum layer, it can make the rock salt dissolving in less appropriate undersaturated salt water drilling fluid, and enlarge borehole.In the wellbore structure, considering of casing damage caused by salt and gypsum layers creeping, and its effects on the casing and cementing, in order to save time for cementing, reduce the cost and risk of cementing, ensure running casing smoothly andcementing with high quality,this paper makes the design scheme of casing program.In the well trajectory, considering thatthe directional drilling work can not be taken in the gypsum layer well section, so it needs design the well body structure to make sure it can achieve the stable helical drilling goal before entering the saltgypsum layer.In BHA, considering that if useful packdrilling, it is easy to cause downhole accident, so it is necessary to choose the right tools and BHA.The double centralizer drilling tool is used during the drilling, it avoids the long borehole reaming because of the slack off, and can stabilize the deviation.In engineering measures, according to the characteristics of salt gypsum layer, this paper provides a series of reasonable engineering measures to reduce the occurrence of downhole complicated conditions, short the drilling cycle.By the optimization of the drilling design inthis field, we got the suitable engineering designfor the salt gypsum layer.The result shows that it can greatly reduce the downhole complicated conditions,shorten the drilling cycle,and get a very goodeconomic benefits by using the technique for the salt gypsum layer drilling.