Currently the options for directional drilling of larger hole sizes, such as those greater than 6", with Coiled Tubing Drilling (CTD) are limited. This paper introduces a new system that utilizes a 5.0" BHA with a Rotating Orienter. The BHA is the first drilling tool to utilize a solid state MEMs gyro for directional measurement at all inclinations from vertical to horizontal. This paper aims to show that the use of this type of tool in combination with a Hybrid Drilling Rig can provide a technically and economically feasible alternative, which could expand the size of the CTD market. The paper reviews a 5-well drilling program that has been carried out in order to assess the capabilities of the tool and the drilling techniques used. The 5 wells consist of directional and horizontal profiles and both mud and an air mist were used as the drilling fluid. Details of the equipment used, the performance of the tools and lessons learnt from the operations are all provided. All initial aims of the project were met with the tools reaching the target zone on all wells. Accurate, reliable and efficient drilling was demonstrated, whilst drilling hole sizes ranging from 6.25" to 8.5".

This paper describes a recent Directional Coiled Tubing Drilling (DCTD) job that was completed for an independent operator in the Appalachian Basin. The objective was to access target zones identified adjacent to a recently drilled, vertical well using a lateral sidetrack. The target thickness was around 15ft so accurate depth control was critical. It was also considered essential that the entire reservoir section be drilled underbalanced to minimise formation damage. The challenge was to deliver a productive horizontal sidetrack in an effective and cost-efficient manner. The field development strategy required costs to be kept to a minimum, but the use of high-tech equipment was essential to delivering the production improvements. A 3.2 inch DCTD Bottom Hole Assembly (BHA) and a specialised DCTD engineering software package were enabling technologies. A multi-disciplinary approach was adopted to plan and execute the sidetrack. This approach required inputs to the planning process from all stages in delivering the well, which included: 3D seismic, well trajectory planning, drilling engineering, completions. This project was ultimately successful in that a dry hole was re-entered and sidetracked to create a productive well, thereby validating the technology and multi-disciplinary approach of the team. The lessons learned from this operation can be used to optimise the planning of future wells and maximise the value of re-entering marginal wells and fields.