The Establishment And Application Of Three Pressure Profiles On A Block Of Iran

In the field of petroleum industry, drilling is an important part of petroleum explorationand development and it costs for more than half of the entire petroleum production costs. Forthe drilling operation involve a variety of complex geological structure, the phenomenon ofwellbore instability such as the borehole collapse, necking, sticking occurs frequently. Thewellbore instability seriously interfere the normal drilling process, increased production costsand adversely affects the follow-up of petroleum process and protection.Currently, the petroleum exploration and development of deep-sea has become a maincompetitive field for many oil companies and it is the main trend of petroleum process in thefuture. The South Paris M area of Iran, located in the deep-sea zone of the Persian Gulf. Thegeological structure of this area is complex, which contains abnormal pressure, sensitive shaleand anhydrite layers. The wellbore instability of this area is serious such as borehole collapseand the block off, and also the phenomenon of loss circulation is very serious.Based on the theoretical research of wellbore instability, we first conduct coreexperiments, combined with the log data from the field, we calculate the mechanic parametersof the M area. According to process situation, we use the Eaton method to calculate theformation pressure and use the Huang to calculate the earth stress. Then on the basis ofanalysis about the stress state of the borehole, we establish calculation model of formationcollapse pressure and formation fracture pressure which are suitable for M area and figure outthe formation collapse pressure and formation fracture pressure of M area. And then we coulddraw the profile of three pressures and figure out the safe drilling fluid density window Bycollecting the loss circulation cases from some wells near the M area, we analyze the causesof the loss circulation and propose other suitable measures to prevent loss circulation andformation collapse and laid a theoretical foundation for propitious development of this area.