Use of Salt-Tolerant Friction Reducer for Coiled-Tubing Applications in Unconventional Shale Formations

Abstract

Wells in the oil-and-gas industry continue to be drilled to deeper depths. These wells present complex challenges for completion and intervention operations because operators demand the same level of performance achieved on shallower wells while providing a cost-effective and safe solution. The size of coiled tubing (CT) deployed in deep-reach wells is maximized to achieve a greater level of performance and operational efficiency, while reducing the pressure requirements of equipment. However, weight restrictions, reel capacity, depth, and trajectory of the well can limit the size of CT that can be used. Using a new cationic polymer friction reducer allowed CT operations to achieve higher rates and velocities while maintaining hydrostatic pressure and lowering surface-treating pressures. The friction reducer has the following attributes: It is salt tolerant, which enables a wider scope of use.Effective at low concentrations.Easily mixed on-the-fly.Compatible with nonionic additives.Can be used up to 200°F.Compatible with shale formations.Extremely rapid hydration.Created for use with water-based fracturing fluids in unconventional shale formations.Gives the customer the ability to reuse flowback and produced water without damage to the formation or addition of fresh water. This paper describes the new friction reducer and the benefits of using it in unconventional shale formations. Also included is a case history to demonstrate the success of the system in CT drillouts. These field trials provided data to confirm the following benefits. A 25% treating-pressure reduction was achieved; 20% was predicted using an existing friction reducer.Using a friction reducer lowers pumping pressure and hydraulic-horsepower requirements.The system enables increased pumping rates, lowered surface-treating pressure, and higher velocities.Cost savings were achieved and and value was added to the operator.

Effect of polymer on gas flow behavior in microfractures of unconventional gas reservoirs

“…Friction reducers that are mainly polyacrylamide based serves as one of the primary additives in slickwater fracturing fluid to reduce the friction drag related to high pump rate. The friction reducer could change the turbulent flow to laminar flow by interacting with turbulent eddies, and the reduction of energy loss could reach as much as 20%e80% in laboratory experiments and 30%e90% in field applications compared with fresh water (Kaufman et al, 2008;Rimassa et al, 2009;Shah and Kamel, 2010;Sun et al, 2010;Lindsay et al, 2011;Paktinat et al, 2011). The concentration of polymer friction reducer is about 1 wt% in slickwater fracturing fluid, but a great amount of polymer would remain in microfractures after flowback considering the large volumes of fracturing fluid required in slickwater treatments (Carman and Cawiezel, 2010;Zhou et al, 2011;Sun et al, 2014).…”