Abstract: This paper is the second part of APPLICATION of DRILLING FLUID TECHNOLIGY in KENKYAK OILFILD.The reservoirs in Kenkyak oilfield are deep and high
pressured reservoirs with complicated geological condition. The main characteristics of formation are :the salt formation is so developed that may reach about to 3000 meter thickness in permian above main area of salt dome .Reservoir pore pressure coefficient of carboniferous system is up to 1.90-1.94. Because carbonate rock which is the main reservoir developed many cracks that caused not only mud loss but also well kicked, and
the safety density window of drilling fluid was narrow, first lost circulation then well blowout was easily happened. In the past thirty years ,many drilling accidents such as well blowout, mud loss, well slough, stick pipe were often happened .The obvious characteristic of drilling engineering was to have many accidents ,slowly pace and lower successful rate .It seriously influenced
drilling works that many drilling accident happened by the complicated geological condition causing .Based on these characteristics of formation ,a series drilling fluid technologies for preventing accidents were developed by Southwest petroleum institute (SWPI) ,and then used in 9 wells in Kenkyak oilfield successfully during 2002 and 2003 year. By adopting these technolo
gies ,the remarkable application effects have been achieved ,such as the drilling accident rate greatly reduce, the drilling pace obviously improved , drilling successful rate was up to 100%.

Key words: Kenkyak, salt bed, rheology, safety density window, lost circulation, sticking prevention