In this work, experimental investigation was carried out on xanthan gel and xanthan foam rheology employing a pipe flow viscometer at 1000 psi. A nominal ½" stainless steel pipe was used as the flow conduit. Xanthan concentrations of 20, 30, and 40 lb/Mgal were used as the gelling agent to prepare xanthan fluids. Surfactant at 0.5% (vol.) was used as the foaming agent. Nitrogen was used as the gas phase. Foams were prepared and tested for qualities ranging from zero to 80% at various shear rates and at temperatures ranging from 75 to 200 o F.The flow data showed that both xanthan gel and xanthan foam exhibited a behavior analogous to Herschel-Bulkley model fluids. It was found that the foam viscosity increases as the foam quality increases and more viscous liquid phase generated higher foam viscosities. The increase of temperature had an adverse effect on foam viscosity and stability. Viscosity isotherms were generated for the xanthan foam.New empirical correlations for the xanthan gel and xanthan foam have been developed from the experimental data generated. These correlations are functions of liquid phase properties and foam quality and can be used to predict apparent viscosity of foam fluids for the conditions investigated. The use of these new correlations will provide a better estimation of the xanthan gel and xanthan foam fluid rheological properties.
This paper presents case studies of several leases containing horizontal wells in the Haynesville shale. The studies involve the successful use of completion diagnostics: fluid tracer, proppant tracer, and offset wells pressure monitoring. The diagnostics were used to evaluate fracture propagation, connectivity and communication (between stages and offset wells) and the impact on production performance for different completion methodologies.
Proppant tracers were used to identify cluster efficiency, fracture geometry and communication between stages. Fluid tracers result provided the extent of fracture connectivity between offset wells and show fracture propagation dependency on well spacing and sequence of fracturing. Furthermore, fluid tracers provided an estimate of lower bound on the fracture connectivity, as well as a qualitative measure of stage contribution based on the load fluid recovery period during the initial production phase. Depletion and treatment volume were found to play a key role in fracture propagation and tracer migration. The instantaneous pressure response in monitoring wells during the fracturing operations of adjacent wells was determined to be related to well spacing and the fracture treatment volume. Fracture propagation was found to positively impact the production performance of the depleted wells, thereby changing their original production decline.
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