From Advanced Drilling Solutions: Lessons from the FSU, Volume II


Utilization of air (or gas) instead of drilling fluid for well borehole cleaning from drill cuttings was the clearest example of the effect the Law of Differential Pressure on drilling efficiency, one of the most general laws of the well drilling process. This differential pressure effect in the conditions of using drilling mud has been discussed in this book before see Chapter 5.

The author of this chapter witnessed this effect for the first time in 1957, while drilling one of the exploratory wells at the Telnovsky coal prospect in the Sakhalin Island. When the drillers had 40 m left to drill to the TD at the depth of 165 m, a rapid temperature drop caused freezing of the stream that was used as a source of water for making drill mud. The unsuccessful attempt was then made to use the melted snow for the borehole cleaning because of the very intensive lost circulation at the bottomhole.

At this point, the decision was made to proceed with well drilling to the TD using air for the borehole cleaning. The drillers used a compressor unit to pump air downhole. The first trial of the new method was extremely successful. In andesite and hard siltstone, a TCI drillbit showed 7 m/hr rate of penetration, which was several times faster, as compared to the earlier results of drilling using the conventional method of the borehole cleaning. In the 1950s, similar results were achieved in other areas of the FSU, such as...

Products & Services
Measurement While Drilling (MWD) Systems
Measurement while drilling (MWD) systems report wellbore position, drill bit performance, and drill string orientation to an operator to maximize drilling productivity. It is related to logging while drilling (LWD).
Earth Drilling and Boring Services
Earth drilling and boring services provide well drilling, quarry drilling and blasting, large site excavation, and related services.
Mud Pumps
Mud pumps are large, reciprocating pumps that are used to circulate the mud on a drilling rig. A typical mud pump is a double- or triple-acting, two- or three-cylinder piston pump whose pistons travel in replaceable liners and are driven by a crankshaft.
Mud Cleaners
Mud cleaners are two-stage solids control equipment that are composed of several hydrocyclones mounted over a vibrating screen, known as a shale shaker. Mud cleaners are used to remove solids from drilling fluid and act as 2nd and 3rd phase solids control equipment.
Downhole Motors
Downhole motors consist of a section of drill string that contains a progressive cavity displacement pump (PCDP). Drilling fluid is pumped through the downhole motor providing additional power to the bit while drilling.

Topics of Interest

Introduction Subsequent to the development of rotary drilling and the increase of borehole depths, engineers developed the concept of decreasing drillstring round-trip time to change the worn bit.

OVERVIEW The term aerated fluids describes the broad category of drilling fluids that are basically incompressible fluids injected with compressed air or other gases. Aerated drilling fluids have...

In order to make reasonable predictions of the flow characteristics for direct circulation air and gas drilling operations, aerated fluids drilling operations, and stable foam drilling operations, it...

Formation pressures less than the static pressure of a column of fresh water or oil require the use of a lighter fluid, such as air, to be injected with mud to obtain less overbalance and underbalance...

Overview Underbalanced drilling is defined as drilling operations where the drilling fluid pressure in the borehole is less than the pore pressure in the formation rock in the open-hole section. By...