Clayrocks, and shales in particular, represent approximately two-third of all sedimentary rocks. In oil and gas drilling operations, shales constitute 80 % of all the drilled sections, mainly because they overlie most hydrocarbon bearing reservoirs. Furthermore, several countries are considering clayrocks as possible host lithologies for radioactive waste confinement, and therefore carrying out...

Large amount of drilling waste associated with the expansion of the Orinoco Oil Belt (OOB), the biggest proven reserve of extra-heavy crude oil (EHCO) worldwide, is usually impregnated with EHCO and highly salinized water-based drilling fluids. Oxidative exoenzymes (OE) of the lignin-degrading enzyme system (LDS) of fungi catalyse the oxidation of a wide range of toxic pollutants. However, very...

a r t i c l e i n f o The use of high-volume horizontal hydraulic fracturing (fracking) has increased substantially over the past five years in the United States. Use of this drilling technology to extract natural gas from hitherto impermeable shale is expected to increase even more in coming decades. Two institutions, integration contracts and well spacing requirements, evolved to mitigate the...

As hotspots of local biodiversity in the deep sea, preservation of cold-water coral reef communities is of great importance. In European waters the most extensive reefs are found at depths of 300 - 500 m on the continental margin. In Norwegian waters many of these reefs are located in areas of interest for oil and gas exploration and production. In this study drilling was carried out in the Mor...

Solids control equipment at the rig site is used to remove rock cuttings or low-gravity solids (LGS) from drilling fluids to allow the fluid to return to the active system in a re-usable condition. Typical equipment, such as shakers and centrifuges, remove LGS particles greater than 5-7 microns. Build up of finer solids in the fluid can create problems for efficient drilling such as drillpipe s...

A system that applies a method of knowledge-intensive case-based reasoning, for repair and prevention of unwanted events in the domain of offshore oil well drilling, has been developed in cooperation with an oil company. From several reoccurring problems during oil well drilling the problem of ”lost circulation”, i.e. loss of circulating drilling fluid into the geological formation, was picked ...

the narrow operating window between pore pressure and fracture pressure makes drilling difficult in some operations. a feasibility study of managed pressure drilling (mpd) is carried out on iran darquain oil field. the previous wells drilled in this field showed that mud returns were lost during drilling gadvan formation. the present work addresses this problem by means of surface back pressure...

Kick occurrence is a possible event during a drilling process. It is required to be handled immediately using a well control method to avoid blowout, financial losses and damages to the drilling crew. Several methods including driller, wait and weight, and concurrent are applicable in the drilling industry to control a well during a kick incident. In this study, typical well control methods wer...