Horizontal Drilling in Saudi Arabian Oil Fields: Case Histories

Al-Buraik, K.A.; Pasnak, John M.

doi:10.2118/25592-ms

Cited by 4 publications

(2 citation statements)

References 1 publication

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“…The Buff Berea mineralogical composition was obtained using X-ray diffraction (XRD). Buff Berea core samples have a bulk density of 2.07 g/cm 3 . The average porosity was 20.28% with a standard deviation of 0.26, while the permeability was 150.77 mD with a 2.05 standard deviation.…”

Section: Core Samples Preparation and Characterizationmentioning

confidence: 99%

“…The mineralogical compositions of the rock formations and the chemical activity of the drilling fluids play a critical role in the rock-fluid interaction, and downhole drilling conditions such as temperature, pressure, and exposure time control the degree of interactions during drilling operations. Most wellbore instability problems were reported during the long exposure time during drilling operations [3,4]. Formation damage is another effect of long exposure time.…”

Section: Introductionmentioning

confidence: 99%

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Exposure Time Impact on the Geomechanical Characteristics of Sandstone Formation during Horizontal Drilling

et al. 2020

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The rock geomechanical properties are the key parameters for designing the drilling and fracturing operations and for programing the geomechanical earth models. During drilling, the horizontal-section drilling fluids interact with the reservoir rocks in different exposure time, and to date, there is no comprehensive work performed to study the effect of the exposure time on the changes in sandstone geomechanical properties. The objective of this paper is to address the exposure time effect on sandstone failure parameters such as unconfined compressive strength, tensile strength, acoustic properties, and dynamic elastic moduli while drilling horizontal sections using barite-weighted water-based drilling fluid. To simulate the reservoir conditions, Buff Berea sandstone core samples were exposed to the drilling fluid (using filter press) under 300 psi differential pressure and 200 °F temperature for different exposure times (up to 5 days). The rock characterization and geomechanical parameters were evaluated as a function of the exposure time. Scratch test was implemented to evaluate rock strength, while ultrasonic pulse velocity was used to obtain the sonic data to estimate dynamic elastic moduli. The rock characterization was accomplished by X-ray diffraction, nuclear magnetic resonance, and scanning electron microscope. The study findings showed that the rock compression and tensile strengths reduced as a function of exposure time (18% and 19% reduction for tensile strength and unconfined compression strength, respectively, after 5 days), while the formation damage displayed an increasing trend with time. The sonic results demonstrated an increase in the compressional and shear wave velocities with increasing exposure time. All the dynamic elastic moduli showed an increasing trend when extending the exposure time except Poisson’s ratio which presented a constant behavior after 1 day. Nuclear magnetic resonance results showed 41% porosity reduction during the five days of mud interaction. Scanning electron microscope images showed that the rock internal surface topography and internal integrity changed with exposure time, which supported the observed strength reduction and sonic variation. A new set of empirical correlations were developed to estimate the dynamic elastic moduli and failure parameters as a function of the exposure time and the porosity with high accuracy.

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Section: Core Samples Preparation and Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exposure Time Impact on the Geomechanical Characteristics of Sandstone Formation during Horizontal Drilling

et al. 2020

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Field Based Criteria For The Design of Safe Mud Weight Window

et al. 2005

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Field based parameters like initial mud weight used for drilling, mud weight increment and problems per well were used to analyze wellbore instability, identify different instability mechanisms and design safe mud weight window for drilling horizontal wells. These parameters were used first on the drilling data of vertical wells to develop the procedure for the analysis of wellbore instability and identify the mechanism of instability. The developed procedure was then applied to the drilling data of directional wells to show the dependence of mud weight on the inclination and azimuth of the well. Finally, the procedure was applied to horizontal wells data along with the concept of critical washouts to infer the safe mud weight window. The safe mud weight window is validated on another set of drilling data showing 90% success rate.

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Wellbore Stability Analysis for Trouble Free Drilling

et al. 2015

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This study systematically investigates the mechanical instability of a wellbore as a function of rock mechanical properties and in-situ earth stresses, and validates the predicted failures with post-drilling problematic wells. Results from this study will help to avoid wellbore instability related issues. Extended Reach Wells (ERD) were drilled in field X through shale formations inter-bedded by unconsolidated sandstone formations and carbonate formations which experienced severe wellbore instabilities. Rock mechanics lab tests were performed on preserved core samples and all the available well logs were obtained and subsequently analyzed thoroughly to develop the rock mechanics properties profile. Daily drilling reports were analyzed and this drilling history was used to evaluate the best failure criterion for modeling purposes. Accordingly, Mogi-coulomb was found to be the most appropriate failure criterion that matches the drilling history failures with predicted failures and can be used for more accurate future wellbore problem predictions. An industrial geomechanical software was used to build a Mechanical Earth Model (MEM). The software output was calibrated and validated with the observed failed wellbore condition in selected drilled wells. Subsequently, the root causes of different wellbore instability problems were identified. After preliminary validation of the MEM, the safe mud weight window for drilling future wells was predicted with respect to each formation by providing plots for different inclinations and azimuths. The safe mud weight windows for drilling in any inclination, azimuth and measured depth for Aruma, Rumaila, Ahmadi, Safaniya, Biyadh and Buwaib were found and reported. Furthermore, the safest mud weight window that works for the entire section at any inclination, azimuth and measured depth was discovered and reported for the fisrt time. Results from this study indicate that the predicted mud weight window profile could be adopted in future drilling operations for safe problem-free drilling in problematic formations.

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Horizontal Drilling in Saudi Arabian Oil Fields: Case Histories

Cited by 4 publications

References 1 publication

Exposure Time Impact on the Geomechanical Characteristics of Sandstone Formation during Horizontal Drilling

Exposure Time Impact on the Geomechanical Characteristics of Sandstone Formation during Horizontal Drilling

Field Based Criteria For The Design of Safe Mud Weight Window

Wellbore Stability Analysis for Trouble Free Drilling

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