The development of basement reservoirs can add significant upside to regional reserves but because of perceived drilling complexity are often overlooked or underexplored. Modern drilling technologies, such as directional drilling and formation evaluation while drilling, have been shown to improve commercial viability of appraisal and development projects in frontier areas. A granitic Type-1 fractured basement reservoir offshore West of Shetland was horizontally drilled and evaluated by means of directional drilling (DD) and logging-while-drilling (LWD) technologies. This was the first time that drilling and completion of a 1-km horizontal basement well had been attempted in the UK, and the project goals were successfully achieved. The project as planned fell into the extended-reach drilling (ERD) envelope, defined as a well in which the ratio of measured depth (MD) is greater than two times the vertical depth. The ERD ratio [MD to true vertical depth (TVD)] was 2.21. This success resulted from a combination of drill bit selection, bottomhole assembly (BHA) stabilisation optimisation, rotary steerable drilling system usage, and close cooperation between the operating company and service providers. The logging data acquired were of sufficient quality to support detailed petrophysical study. The basement reservoir section was shown to have significant storage capacity within a network of fault zones, joints and microfractures, as identified using a LWD resistivity microimaging tool. The LWD imaging data were compared to offset well wireline imaging data and used to evaluate the microfracture and joint network across the horizontal section. This evaluation confirmed the storage capacity of the reservoir and was later supported by successful commercial extended well testing. In addition to fracture characterisation, the LWD data were successfully used to evaluate the fracture porosity. Fracture porosity and fracture characteristics in the horizontal well were both consistent with those derived from previously drilled inclined wells, providing the operator with confidence in its reservoir model. This paper documents the drilling and petrophysical evaluation of the first 1-km horizontal well in a fractured basement reservoir on the UK continental shelf. Further development of similar hydrocarbon-bearing basement fields would greatly increase regional recoverable reserves.