Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/118004
Type: Thesis
Title: Geological representivity of returned drill cuttings from coiled-tubing drilling in a hard rock environment
Author: Dietman, J.
Issue Date: 2015
School/Discipline: School of Physical Sciences
Abstract: With the global discovery rate of mineral deposits decreasing and with near surface resources being gradually depleted, there is a need for new technologies to aid in the discovery of mineral deposits under deep cover. In order to increase the productivity of deep exploration, the Deep Exploration Technologies Cooperative Research Centre (DET CRC) is building a Coiled-tubing (CT) drill rig, which is accompanied by a top-of-hole Lab-at-RigĀ® system, allowing real time geochemical and mineralogical analysis. Rather than produce core, CT drilling returns cuttings to the surface within the drilling fluid. These cuttings are passed through a Solids Removal Unit (SRU) which separates cuttings from the drilling fluid, from which they can be prepared for analysis. Drill cuttings from the CT rig can have broad and heterogeneous particle size distributions (PSD). Enroute to the surface, these drill cuttings can be subjected to differential rate of return and mixing of particles from adjacent depths, which can cause smearing in the geochemical signal. A series of experiments were conducted at 100 m depth through simple, single-layered pseudostratigraphies using full-faced diamond and Wassara hammer drill bits, in order to quantify this smearing effect, and provide advice on how to mitigate against it. Samples were taken before and after the SRU, to assess the contributions of up-hole flow and the SRU to smearing. Pre-SRU samples were found to have consistently decreased smearing compared to post-SRU samples. The results indicate that limited smearing is occurring during up-hole flow, likely due to efficient cutting transport at the high flow rates (120-150 L/min) associated with CT drilling. Smearing within the SRU is most likely the result of particle separation and settling rates in the shaker tank. This smearing can be mitigated by simple modification in the design of the SRU, notably by reducing the water column.
Dissertation Note: Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2015
Keywords: Honours; Geology; geochemistry; coiled-tubing drilling; solids removal unit (SRU); annulus; mineral exploration; pXRF; particle size distribution (PSD); depth fidelity
Description: This item is only available electronically.
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals
Appears in Collections:School of Physical Sciences

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