Rheological Characterization of Hydraulic Fracturing Fluids, Cement Slurries, and Drilling Muds: Fluid behavior and characterization of rheologically complexed fluids such as polymeric solutions and gels, used widely in the petroleum industry, are being investigated at the reservoir conditions using the high pressure fracture simulator. The simulator has numerous unique capabilities, and it is equipped with state-of-the-art instrumentation. The operating conditions of the high pressure simulator are 250 F and 1200 psi. The fluid mixing procedure, wellbore shear history, perforation shear, fracture shear history, as well as temperature histories in the wellbore and fracture are simulated. Wall slippage and nonhomogeneous flow phenomena associated with the crosslinked fluids have also been investigated. More meaningful rheological data are gathered with various fluid systems used today in the industry. The research program has produced results that support industry assumptions and contradict others. 

Dynamic Fluid Leak-off Mechanisms: Quantifying the rate at which fluid can be lost to a permeable fracture face is important for a successful fracturing treatment design. The mechanisms which help control fluid loss to the rock matrix have not been well understood. The influence of some mechanisms can be calculated while others must be characterized experimentally. Extensive efforts are expended using the high pressure simulator to investigate the effects of various fluid loss mechanisms, particularly, the wall building/filter-cake formation as a fluid loss control mechanism. Studies are conducted to obtain fluid loss data over a significantly large surface area. The role of fracturing fluid and fluid loss additive on the fluid loss mechanisms under downhole conditions are being investigated. To investigate the effect of surface texture, studies are conducted with surface-roughened synthetic rock as well as natural rock. The fluid loss through natural fractures is also being studied. 

Near-Wellbore Fluid Behavior/Perforation Pressure Losses and Downstream Pressure Recovery: Perforation pressure losses can have a significant effect in hydraulic fracturing treatments, especially in limited-entry designs and when surface treating pressure is near the maximum allowable. The presently available information is not adequate for reliably estimating perforation pressure losses. Only limited data are available to industry for estimating discharge coefficient of fluids. It is apparent from the literature that many factors which may affect perforation pressure losses have not been investigated sufficiently to provide confidence in predictions of perforation pressure losses. The effects of fluid type, perforation size, fluid viscosity, perforation density and distribution, system pressure, and proppant type, size and concentration on the perforation pressure losses are being investigated in a simulated wellbore with perforations and pressurized fracture downstream. The erosional effects of proppant-laden fluids on the perforation pressure losses are also investigated. 

Proppant Transport in Hydraulic Fracturing: The objective of this investigation is to quantify proppant bed formation under dynamic settling conditions, to determine conditions under which convective settling, encapsulation, fluid displacement, and stratified flow occur, and to quantify these phenomena when do occur. Correlation of results from these studies with measurements of fluid and proppant properties will indicate the effects of fluid and proppant properties on proppant transport. The tests are conducted in the large-scale high pressure fracture simulator which is instrumented with the state-of-the-art fiber optic vision system. This vision system allows one to quantify the motion of displacement fronts, settling rates, and proppant concentrations. Dynamic settling is also being investigated. 

Flow of Fluids Through Deviated and Horizontal Wells: Flow and behavior of fluids, particularly proppant-laden fluids, during hydraulic fracturing treatments through highly deviated and horizontal wells are not well understood. The quantification of the effects of various parameters, such as well deviation, slurry properties, wellbore geometry, etc. On the friction losses in tubular conductors are presently non-existent. Stratification within fluid and settling of particles in the wellbore can happen under certain conditions which may result in excessive friction losses and in some instances it may result in a screen-out of the well. Experimental investigation of these parameters on the friction losses should be conducted. 

Heat Transfer Characteristics of Polymer Solutions and Gels: Accurate design and control of cost-effective hydraulic fracturing treatments require a thorough knowledge of the fracturing fluid properties at the operating conditions. This in turn requires a sound understanding of the heat transfer characteristics of the fluid. The most commonly used fluids are non-Newtonian and viscoelastic in nature. Unfortunately, heat transfer data for these fluids are non-existent. An experimental investigation is underway whereby determine heat transfer characteristics of hydraulic fracturing fluids. A full-scale double pipe heat exchanger in conjunction with the coiled tubing fluid pre-conditioning system is sued to acquire necessary data. Fluids investigated include linear polymeric solutions as well as various crosslinked fluid systems. The effects of flow rate, operating temperature, pH, and level of shearing, on the heat transfer behavior of the test fluids are being investigated. Preliminary results show a significant difference between the heat transfer coefficient of water and those polymer fluids tested.