In selecting the most suitable type of drilling fluid, many different factors must be considered. Overall what is required is a mud system that gives the lowest overall cost of drilling each hole section, except for through the reservoir. The direct cost of the fluid itself (the cost per barrel of mud) is but one component of this overall cost. If serious hole problems occur because the mud was not optimized for the formations in an effort to “save money,” obviously much more money will be spent than would have been saved on the mud bill.Continue reading “Designing the Drilling Fluid”
what is a shale？ it’s quite an important question depending on which geologist you speak to. You’ll get a different answer. But in a very basic sense: shale is mud stone. The mud that has been compressed over a thousands or millions of years and been turned into stone.
Much of the drilling in unconventional resource plays occurs in unstable shales, which are usually fractured and can be easily destabilized. Successful drilling through them can be difficult at best, and many high-angled holes in these plays are often lost due to mechanical instability. This paper looks at the drilling problems of shale gas drilling from the theoretical perspective of Wellbore Pressure Management, (WPM) and keys in on the effects of Equivalent Circulating Density (ECD) while drilling and on the effects of Equivalent Static Density (ESD) when there is no circulation.