Quantitative Properties From Drill Cuttings To Improve the Design of Hydraulic-Fracturing Jobs in Horizontal Wells

Abstract

Summary The study proposes a method for quantitative determination of porosity, permeability, and rock-mechanics properties from drill cuttings of at least 1 mm. The porosity value is used for determining a brittleness index by implementing sonic-derived porosity theory and a dipole sonic log from an offset well. A new parameter is introduced in this work to give a quantitative value to microscopic observations related to natural-fracture features in drill cuttings. It is called “frac value” and in conjunction with the brittleness index and permeability constitutes the main result of the methodology: the cut log. Quantitative data extracted from drill cuttings are important because the amount of information collected in horizontal wells drilled through tight formations, including cores and well logs, is rather limited in most instances. This paper is based on a Canadian case study with implications for selecting optimum intervals for hydraulic fracturing in a tight gas reservoir. However, the method should also be suitable for global applications in all types of reservoirs (unconventional and conventional) where good-quality drill cuttings might be available. Data extracted from the previous steps are useful for multistage hydraulic-fracturing 3D simulation of horizontal wells. This provides additional information to stimulation designers for deciding where to initiate hydraulic fractures and how to optimize fracture spacing and fracture size per stage instead of considering a homogeneous reservoir volume throughout the whole lateral section. It is concluded that the proposed method provides a useful tool for evaluation of direct sources of information that are available in many cases (drill cuttings) but are rarely evaluated quantitatively. The proposed method allows improved design of multistage hydraulic-fracturing jobs in horizontal wells.