This dataset describes the gas resources in shales and other tight reservoirs in the North Sea area. The hydrocarbon content is estimated using Monte Carlo simulations. The estimates of adsorped gas, free gas and GIIP (Gas Initially In Place) are shown for the percentiles P10, P50 and P90. At P90, 90% of the calculated estimates will be equal or exceed the shown figure. At P10, it is only 10% of the calculated estimates that exceed the shown value. A more detailed description of the data is found in the report, GARAH Deliverable 2.3. Updated assessment of the conventional and unconventional resources of the North Sea Basin. https://repository.europe-geology.eu/egdidocs/garah/garah-d-2-3-assess-conv-unconv-res-north-sea.pdf.