An experimental method to measure the porosity from cuttings: Evaluation and error analysis

As an economical approach to formation evaluation, drill cutting analysis provides significant information on petrophysical parameters which help us understand reservoir behavior. Researchers are gradually paying more attention to the study of drill cuttings which potentially promote and enrich the reservoir characterization process. This research concentrates on measuring the porosity from cuttings. An evaluation of the improved method is presented by comparing porosity data estimated from artificial cuttings with various sizes to the reference values measured from core samples. Since the estimation of bulk volume is not practically possible for cutting samples, the measurement of porosity from cuttings depends on the grain volume Vg and the pore volume V . Instead of applying an average grain density for calculating grain volume, the method presented by IFP, grain density directly estimated from conventional core analysis for is used. Additionally, the pore volume is calculated by using a saturation method adapted to cuttings. The cuttings are obtained from crushed cores with different permeabilities and screened into four different sizes. The analysis of results shows that estimating the porosity from cuttings by using the proposed method is effective and reasonable. There is a close relationship between the results and the size of cuttings. After the removing excess liquid between cuttings, the measured porosity from all cutting sizes is estimated. Cuttings with the smallest size A (0.425-0.85 mm) show the greatest deviation from the reference value. For cuttings with larger size, the measured porosity varies in a smaller range over time compared with that from cuttings of smaller size. We choose one hour as the optimum desaturation time which corresponds to the base results obtained from core data. The largest size D (2.8-4.0 mm) gave the best results with minimum error.