Abstract Underbalanced Coiled Tubing Drilling minimizes formation damage and lost circulation but poses challenges in horizontal wells with small diameters. This study highlights the advantages of rock cuttings analysis during UBCTD in clastic formations. Using XRF and XRD techniques, high-productivity zones were identified following elemental ratios and mineral analysis in quartz-dominated lithology. The result of study demonstrated that this workflow has potential to replace LWD technologies, enhancing precision in chemosteering and well placement in complex formations. The method combines microscopic observations to assess grain sorting and arrangement with systematic quantitative mineral analysis using X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) techniques for detailed elemental composition of cuttings from eight lateral sections from different wells. Delimited zones are tentatively correlated with hydrocarbon productivity, offering valuable insights into clastic formations characteristics and their relationship to well placement and productivity. Clay minerals and anhydrite cement significantly influence the reservoir quality of the formation, particularly by reducing porosity and permeability. These effects are primarily dictated by the depositional environment and subsequent diagenetic processes. In clastic formations the heterogeneity of depositional settings results in the development of distinct facies, ranging from eolian dune systems to interdune and sand sheet deposits, each exhibiting unique porosity and permeability characteristics. Accurate identification and differentiation of these facies in real-time is critical for chemosteering operations and optimizing hydrocarbon recovery. While the XRD confirmed the purity of various types of clastic reservoir minor changes in clay content (kaolinite, illite) and presence of feldspars in traces identified depositional variations suggested to be related to eolian vs glaciation sedimentations. Similarly, elemental data showing low content of calcium, iron, magnesium, aluminum and potassium oxides with presence of strontium, as well as a key trace elements Zn, Zr, Ni and Rb to name just a few, allowed for better characterization of sandstones purity. Characterizing rocks through microscopic analysis and quantitative compositional evaluation can be highly effective for navigating complex well trajectories within slim hole sizes, where downhole tool deployment is challenging. This approach demonstrates significant potential in enhancing reservoir understanding and performance in clastic formations ensuring accurate facies identification and enhanced well placement.
Qubaisi et al. (Tue,) studied this question.