Billy W. McDaniel

Limited-Entry Frac Applications on Long Intervals of Highly Deviated or Horizontal Wells

Long horizontal sections have been used increasingly in moder ate- to low-permeability reservoirs. In these reservoirs, a successful program for applying fracture-stimulation treatments is a key component for commercial success. Historically, such wells have been stimulated with several separate fracture treatments, requiring expensive well operations between fracture stages. Successful zonal isolation for each fracture stage has been a primary reason for the success of this technique. This paper reports recent efforts by several operators to reduce completion costs by extending the application of limited-entry fracturing techniques to very long sections of highly deviated of horizontal wellbores, while ensuring effective fracture stimulation of each perforated section. Many special innovations have been introduced recently for enhancing the applicability of limited-entry fracturing in long, openhole completions and in some uncemented liner applications. Some of these methods have been published; other unpublished methods are presented in this paper. Case histories are presented for both sandstone and carbon ate reservoir completions. Considerations that guided the wellbore azimuth, casing programs, perforating schemes, and fracturing program variables are presented. Known problems and unpredicted formation responses are also discussed.

Harvesting Downstream Energy to Improve Efficiency: Creating Apparent Discharge Coefficients of Jet Nozzles Greater Than 1.3

Fluid movement devices use upstream energy to move fluid from one location to another. Flow nozzles that slightly accelerate fluid motion, especially into the same direction, often exhibit discharge coefficients greater than 1.0. Jet nozzles, however, by definition, create a jet stream that is much faster than the upstream fluid, often exceeding 100-fold higher velocities. Energy used to move this fluid is often very high; jetting efficiencies are generally less than 1.0 and will only approach 1.0 if the shape of the entrance is such that there is no “vena contracta” within its flow regime inside the nozzle.High-pressure nozzles require high horsepower to generate high-velocity fluids. As is commonly performed, power is created using high-powered pumping equipment. Oftentimes, nozzles are used to jet in locations that have high ambient pressures, such as at the bottom of the ocean or inside a deep oil well. At these locations, the hydrostatic pressures could be very high. Pressure at the upstream side of the nozzle would be even higher.This paper discusses the design and use of a unique nozzle that uses the hydrostatic (potential) energy to accelerate the fluid velocity of the jet. In essence, the nozzle uses the downstream energy to perform part of its job, thus, substantially reducing the upstream pressure requirement. This phenomenon was proven to occur using CFD analysis. Laboratory tests have shown apparent discharge coefficients between 1.38 and 1.69, depending on the downstream pressure.Copyright