| Popis: |
The large increase in the use of crosslinked fracturing fluids in the past decade has led to the need for accurate evaluation of their flow properties. Traditional rotational viscometers are inadequate for studying the rheology of these crosslinked fracturing fluids, hereafter called "gels." A recently developed coiled-pipe viscometer is described, and gel response to various temperature and shear histories during preparation and testing is presented as determined by the pipe viscometer. If gel flow properties in the fracture are to be studied accurately with any viscometer, then preparation of the gel, thermal energy input, and mechanical energy input to the test sample should be controlled to duplicate the gel of the fracture. The pipe viscometer developed has the following attributes. Gel preparation is an integral part of the viscometer. Each element of the gel is subjected to the same degree of shear while mixing. The gel develops in-line as it moves to the test section of the viscometer. There are no stagnant periods. Heat transfer occurs from the walls of the conduit to the fluid in flow as in the fracture. Parallel flow sections are incorporated for scale-up information. Results are presented to elucidate the mechanism of gel formation and deterioration, gel stability at high temperatures, and the possible occurrence of slip flow in the fracture. The coiled-pipe viscometer shows potential to stimulate fluid preparation and flow in the fracturing process. |
