Rotary Drilling

Rotary Drilling allows boreholes to be advanced beyond the superficial deposits and through rock or other hard strata to depth.

There are two types of rotary boring, open hole and core drilling.  Open hole drilling can be employed to determine general changes in strata and investigate historic coal mine workings.  It is suitable for rapid drilling to enable core recovery at a greater depth or for the installation of monitoring wells.

Core drilling uses a variety of rotating core barrels and cutting bits in conjunction with different flush media, the choice of which is dependent on the ground conditions encountered and the geotechnical information required.

Strata’s Rotary Drilling Crews are directly employed and are NVQ qualified in Land Drilling and British Drilling Association (BDA) audited to ensure high standards in both safety and quality. The crews are supported by our qualified Geotechnical Engineers who undertake supervisory and technical duties including borehole logging and sampling.

Strata Geotechnics can provide difficult access and ground protection solutions for our Rotary rigs including smaller rigs for restricted access sites. Our crews are experienced in working for many industry sectors particularly on Highways and Rail.

Rotary drilling by Strata Geotechnics at an Elle

What are the advantages of Rotary Drilling?

  • All our drilling rigs are configured with a dual-purpose drill head which allows Dynamic Sampling of the near surface superficial deposits before progressing the hole with coring or open holing
  • Standard Penetration Tests (SPT) can be conducted as the borehole progresses with a number of our rigs now fitted with automatic SPT hammer systems
  • For deeper superficial deposits we can advance the borehole using a Casing Advancement system which prevents borehole collapse
  • Using our rotary sonic system which has a dual-purpose sonic-rotary head so that we can sonically drill through the superficial deposits and follow-on using conventional rotary techniques.

Common Uses

If detailed rock logs are required, we generally use a Geobore triple tube wireline coring system to recover rock core in an as undisturbed condition as possible. The core can then be accurately logged by our inhouse engineers in accordance with the relevant geotechnical standards and dispatched for laboratory testing. Open hole drilling can be employed to determine general changes in strata and investigate historic mine workings.

Flushing clears the cuttings from the cutting face of the core or bit and brings the cuttings to the surface. We can use a variety of flush types including air, water or mud. To reduce mess and water usage we often recirculate the water flush which involves using tanks to settle out the suspended cuttings before returning the water down the borehole.