In fracturing treatments performed in unconventional reservoirs, propping agents are normally placed in the generated fractures using low viscosity fracturing fluids and friction reducers. It is generally accepted that a majority of the propping agents settle closer to the wellbore due to the poor transport characteristics of these thin fluids, limiting the propped area to the near wellbore region. This preferential settling can leave a majority of the generated fracture unpropped, and can result in:

  • Reduced effective fracture-reservoir contact

  • Low productivity and recovery of the stimulated well or reservoir

  • Generation of long un-propped fractures

  • Inefficient usage of the carrying fluids and chemicals

Extensive lab testing was performed to demonstrate the impact of variable viscosity on proppant transport and deposition. Fluids were built that covered a range of realistic slickwater viscosities and were then run through a slot with various proppant types and loadings, to observe the changes in deposition. This included the novel process of changing the viscosity within the same test run to simulate changes during an individual treatment.

The new process resulted in a substantially improved placement and distribution of typical conventional propping agents, including natural sand and ceramic proppant, and the effective placement of the proppants further away from the wellbore creating a longer propped and more conductive fracture.

While designed for unconventional reservoir stimulations, the novel process can also be utilized in fracture stimulations of tight or conventional reservoirs, and results in:

  • Assured connectivity between the fracture and wellbore

  • Maximized propped fracture length and height

  • Maximized reservoir contact

  • Engineered placement of the proppant in fracture or complexity as required

  • Reduced use of water to create a similar or longer propped fracture length

Considering the improved proppant distribution in many simulated cases, this paper will review the development of the new process, present the results, and show the benefits to the user.

The new proposed process to improve proppant distribution will assure better productivity and higher hydrocarbon recovery factors in hydraulically fractured unconventional reservoirs. It will be beneficial for completions and reservoir engineers who wish to improve the drainage area and ultimate recovery in their assets.

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