Development and Field Application of a Low pH, Efficient Fracturing Fluid for Western Siberian Oil and Gas Wells

摘要

Hydraulic fracturing has proven to be one of the best technologies to improve productivity from oil and gas wells. Careful consideration must be given to fracturing fluid selection, particularly when the fluids have to be prepared with local waters. Siberian waters are particularly troublesome because of the presence of iron and bicarbonate and hardness, depending on the water source. Some hydrocarbon reservoirs are under-pressured and require the use of energized fluids, while others are sensitive to water-based fluids due to clay swelling and migration. Proppant pack damage due to gel residue is one the primary causes of low production rates after hydraulic fracturing treatments. To minimize the damage and therefore maximize production, a new premium highly efficient fracturing fluid was developed. This premium system incorporates low polymer loading carboxymethyl guar polymer and a zirconium-based crosslinker. An adjustable crosslink delay makes the fluid ideal for deep well fracturing and coiled tubing treatment as frictional pressure losses can be minimized. The system can be energized or foamed with CO2 and N2 or may also be used in binary foam systems. This paper will compare the new fracturing fluid system with alternative guar borate system used in Russia, in terms of proppant pack cleanup, rheological properties, proppant transport and fluid loss as well as other parameters. Various rheological evaluations using high-pressure, high-temperature rheometers as well as a foam loop; fluid leak-off testing; and proppant pack conductivity and regain permeability evaluations are presented.