... ekofisk field drilling fluid chemistry drilling fluid property reinfection point drilling fluid formulation shale disposal drilling fluids and materials slurry deeper overburden gradient reservoir geomechanics upstream oil & gas drilling fluid selection and formulation hydraulic...

... Abstract A system for acoustic velocity and static Young's modulus measurements on small (mm-size) shale samples is presented. The equipment has been tested on both soft and hard shales, including cuttings. Even though more experimental testing, must be carried out to confirm and improve its...

... Abstract Based on a containment transport model developed for hydrogeological purposes, a numerical method for the analysis of intrusion of potassium ions into a shale has been developed. The scheme has been applied in the back-analysis of KCl-brine exposed specimens of smectite-rich Tertiary...

... Abstract During exposure to different fluids and temperature gradients, the shear strength and the stiffness of shales may change because of changes in their chemical and physical properties. Time-dependent borehole stability models should incorporate these changes in order to capture actual...

... Abstract One of the key time-dependant mechanisms for wellbore failure in shales is the penetration of drilling mud into the formation. Previous studies attempted to predict mud pressure penetration into shales using single-phase flow approach. This can lead to some errors because it ignores...

... Abstract In recognising the petroleum industry's need for a technology to design optimal drilling fluid (weight, type and chemistry) to solve and manage shale instability problems, a collaborative project has been undertaken to develop the technology which will provide the basis for state...

... Abstract Wellbore stability has been traditionally analyzed by comparing the stresses to the formation strength. In addition, most of the problems have occurred in the shales; hence, have been attributed to the chemical interaction between the drilling fluid and the rock. However, field...

... that included a rock mechanics program, mud optimization, and batch drilling. Wellbore instabilities occurred in the Ngimbang Shale, a hard, brittle, anisotropic formation, that is highly stressed. Field measurements of stresses, coupled with laboratory measurements of strength, demonstrated the presence...

... and wells. It was found that stress arching was very significant in the Shearwater field geometry and led to a reduction of the compaction strains within the reservoir till below the critical values. However, the stress arching also reduces the total stresses in shales, faults and slip layers in the rock...

... pressure and geomechanical deformation properties of the formations were determined. Results, observations and conclusions are presented. P. 193 reservoir characterization mechanical property reservoir geomechanics porosity wellbore design valhall fracture shale seismic data subsidence...

... Abstract Stability problems encountered in shale formations significantly increase the cost of drilling operations. It is not possible to identify a single main factor in shale instability; failure mechanisms are only now beginning to be identified, and the dominant processes seem to vary...

... (Kimmeridgian shale) in a number of very highly inclined wells; these problems had not been experienced at lower inclinations. A rock mechanical study was carried out to explain and overcome the stability problems. A series of thick-walled hollow cylinder (HC) tests were carried out on core material...

... Abstract The main operational parameters controlling borehole stability in drilling shales are the density and the chemical composition of the drilling fluid. The density of the drilling fluid provides support of the borehole wall, while the chemical composition of the drilling fluid can...

... to heating of the formation. The results also show the importance of considering the geothermal gradient, and thermal and fluid transport properties of shales in wellbore stability analysis and development of recommendations to manage instability. P. 471 pore fluid pressure upstream oil & gas...

... Abstract Shales are highly anisotropic and are generally characterized by very low permeabilities. In this paper we report results of an experimental study of the relationship between elastic wave propagation anisotropy and permeability anisotropy of an illitic shale. Elastic wave velocity...

... Abstract The specific surface of particles' and the properties of the pore fluid control the sensitivity of shales to a given change in the host environment. In this study, dielectric permittivity measurements are suggested to assess the reactivity coefficient, which is a measure...

... Abstract In order to study the poroelastic behavior of shales, a set of experiments have been performed in an uniaxial strain setup. The shales were cored at a depth about 450m. Assuming Biot's poroelastic theory, the Biot coefficient was determined in a uniaxial strain loading system...

... Abstract Due to the low permeability of shales, excess pore pressures will be induced in the material in response to the volume change of the rock matrix during drilling. These excess pore pressures will reduce the effective confining pressure applied on the material which will lead to a less...

... stress (hundreds of bars) at the wellbore. Osmotic phenomena cannot explain such a high stress, and this specially for non reactive shales (low CEC and hydration capacity). The experimental procedure used to determine material characteristics required for models seems in fact to be unadapted: swelling...

... source rocks. deformation basin stress drop reservoir characterization pore fluid shale bedding plane expulsion elevated temperature diagram source rock mixed failure hydraulic fracturing fracture migration upstream oil & gas shear fracture deviatoric loading stress-strain...