Formation drillability is one of the most important aspects for planning and designing a new oil/gas well since the factors affecting the drilling performance have complex relationships between formation properties, drill bit design and operational parameters. In view of the high operating cost of drilling rigs, if Rate of Penetration (ROP) can be enhanced, it will reduce open-hole formation exposure time and complications associated with it, resulting in significant savings in drilling time and cost can be realized. Normally bit engineers utilize the assumed lithology from mud logs and detailed depth-wise lithology of offset wells. The lithology can also be interpreted from conventional logging data such as Sonic, Gamma and Density. Furthermore, the rock's compressive strength is calculated using Compressional / Shear travel time (Sonic log), Bulk density (Density log) and Shale content (Gamma log). These utilized tools to detect the lithology and rock mechanical properties have an extent of uncertainty due to effects either related to the borehole or drilling fluids that require extensive corrections. That degree of uncertainty subsequently can affect the drill bit design criteria, selection and viability of performance-enhancing features. This present paper reveals a new practical approach as a solution to minimize uncertainty in terms of bit design and selection by utilizing wellbore imaging either LWD and/or Wireline borehole images and lithology & mineralogy from either wireline mineralogy logs "Pulsed Neutron" and/or ROQSACN instrument to precisely deliver an accurate input data to the drill bit design/selection software modules.

Mud loggers are the first (and sadly in some cases the only) people to look at the cuttings. To actually see what the rocks look like, feel like, occasionally even taste. Most people looking at a well will actually look at "wriggly lines" or at best the cuttings descriptions from the loggers or geologist, two or three lines of abbreviations "claystone, light grey to grey, soft to firm, occasionally hard, slightly calcareous, trace fine sand". We have all read them, many of us have written them. These descriptions are incredibly useful and valuable, they are often all we have to understand the actual rocks and geology, especially with older wells. But in a world where we now enter the description and draw the logs with a computer, this information still comes from the subjective view of the logging geologist peering through a microscope In recent years, several tools have been developed to analyze drill cuttings from oil and gas wells. The most commonly used tools include X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDX), bulk density, and pyrolysis. Although each of these tools can be used to develop a limited determination of the in-situ rock character, the combination of three of these tools (XRF, SEM/EDX, and pyrolysis) can provide a more comprehensive picture of formation properties.The combination of XRF analysis with the SEM/EDX analysis is the key to the cuttings workflow. The exact location within the borehole can be determined and a robust mineralogy developed that is independent of normative mineralogy (typical XRF) or operator-interpretive mineralogy (XRD). Additional outputs include relative brittleness index, bulk density, lithology, fractional and textural relationships, total organic carbon (TOC) proxy, and a new porosity index. Trace and major elemental ratios are also available for precise stratigraphic placement. The addition of cuttings pyrolysis enables hydrocarbon typing, producible hydrocarbons, TOC, and total inorganic carbon (TIC) within each sample to be established.Chemical Lithostratigraphy uses whole rock inorganic geochemical (elemental) data, to give information on: Extrabasinal source area dominance and origin (volcanic, metamorphics, igneous, sedimentary), Extrabasinal component weathering or diagenesis (cementation) Intrabasinal components (Palaeoenvironment and insitu origin of sediments) Chemical Lithostratigraphy analysis of cuttings can be done application of automated mineralogical analysis of cuttings samples pre-drilling in defining stratigratic zones via mineralogy/elemental data. And then explore the application of the same data to assist, and in this case lead, the decision making process during directional drilling of the lateral well. The paper will also look at the use of the technology in defining tactical fracc-ing zone based on rock properties (e.g. ductility) determined from the mineralogical, elemental and textural data.This paper will show that through the use of automat...

Lukoil Saudi Arabia Energy Limited(LUKSAR) started a Deep ‘Tight Gas’ exploration campaign in the Rub Al-Khali Empty Quarter in 2006 and nine wildcat exploration wells have been drilled and evaluated with one Appraisal well in its Field Fig. 1. These prospective deep gas discoveries in the Empty Quarter have occurred in relatively High Pressure/ High Temperature (HP/HT) horizons at depths between 15,000 and 20,000 feet, where the stress and temperature are extremely high in addition to low reservoir permeability. This has made the exploration activity more challenging. Well test and clean up results from different completion strategy has not yield convincing results due to many factors. Some of these include: well placement, fluid selection, completions and frac designs. Nonetheless, the starting point in evaluating the success of well operations in the life cycle of a well remains selection of suitable drilling fluid of which its solids and filtrate particles are very friendly to the given reservoir (i.e minimum damage effect). Although the drainage radius of these wells may be several hundreds of feet, the effective permeability close to the wellbore may have a disproportionate effect on the well productivity. This paper summarizes the challenges encountered in the use of water-base mud (WBM) and the subsequent mud filtrate effect on the reservoir permeability through different test analysis on core samples and logs interpretations. But most importantly the result raises the need for continual research and development in the area of formation damage prevention and avoidance in deep gas drilling of ultra-low permeability reservoirs.

Formation drillability is one of the most important aspects for planning and designing a new oil/gas well since the factors affecting the drilling performance have complex relationships between formation properties, drill bit design and operational parameters. In view of high operating cost of drilling rigs, if Rate of Penetration (ROP) can be enhanced, it will reduce open-hole formation exposure time and complications associated with it resulting in significant savings in drilling time and cost can be realized Normally bit engineers utilize the assumed lithology from mud logs, detailed depth wise lithology of offset wells. The lithology can also be interpreted from conventional logging data such as Sonic, Gamma and Density. Furthermore, the rock's compressive strength is calculated using Compressional / Shear travel time (Sonic log), Bulk density (Density log) and Shale content (Gamma log).These utilized tools to detect the lithology and rock mechanical properties have an extent of uncertainty due to effects either related to borehole or drilling fluids that require extensive corrections. That degree of uncertainty subsequently can affect the drill bit design criteria, selection and viability of performanceenhancing features.This present paper reveals a new practical approach as a solution to minimize uncertainty in terms of bit design and selection by utilizing wellbore imaging and lithology & mineralogy wireline logs to precisely deliver an accurate input data to the drill bit design software modules.