Real-Time Advanced Warning of Screenouts With the Inverse Slope Method

Abstract

Unconventional plays require multiple hydraulic fracture treatments placed in vertical or horizontal wellbores in order to be economical. These are very complex operations performed on-location in an orchestrated manner by many contributors. A screenout puts many of the contributors on stand-by status, delays the placement of subsequent stages, and, results in cost overruns due to stand-by charges, wellbore cleanout operations, and, lost production days. Thus, advanced warning of screenouts is a major technical advance in hydraulic fracturing.Advanced warning of screenouts in real-time is a great advantage due to the ability to exercise decision control for early termination of the treatment, or extension of the treatment.A screenout is imminent if the surface pressure slope deviates from the inverse slope (positive surface pressure slope). This allows for early initiation of the displacement (flush) procedure, and prevents leaving in the wellbore excess proppant. When only the designed amount of proppant is left in the wellbore high net-pressure develops, along with adequate packing of the near-wellbore area and a much wider fracture.A treatment can be extended if the surface pressure slope doesn't deviate from the inverse slope (positive surface pressure slope). Thus, if extra fluid and proppant are available on location the treatment can be extended. This would result in a much better placement of the proppant pack, as it would result in a higher net-pressure, a wider fracture, and higher production rates.

Prediction of the Continuous Probability of Sand Screenout Based on a Deep Learning Workflow

“…The Vs/Vf ratio represents proppant accumulation in fractures. The ΔP/ΔVf ratio is similar to the pressure slope returned under a constant pump rate (Massaras and Massaras 2012). The σmin/Ps ratio reflects the change in in-situ stress due to the material injection (Hayashi and Haimson 1991).…”

“…Previous research on the fracturing of conventional reservoirs suggests that the near-wellbore tortuosity of fractures may play an important role in causing screen-out, in addition to fluid leak-off, proppant beach-formation and other factors, according to experiments and field measurements (Barree and Conway 2001;Aud et al 1994;Daneshy 2007). Based on these mechanisms, screen-out may be potentially predicted by interpreting time histories of fracturing pressure based on log-log plots (Nolte and Smith 1981), calculating the configuration of the proppant distribution in fractures (Cai et al 2017), diagnosing the connection between wellbore and formation through the perforations based on acoustic measurements (Merry and Dalamarinis 2020), or inspecting the variation with time of the treatment pressures (Massaras and Massaras 2012), among other indicators. Data-driven approaches have also been introduced for prediction by integrating the inverse slope method with deep learning algorithms (CNN-LSTM) (Sun et al 2020), predicting the fracturing pressure using the locallyweighted linear regression and CNN-RNN (J.…”

“…We, therefore, focus on the continuous diagnosis of screen-out by field data processing, attempting to improve the fidelity of the early warning and define the form of signals that are precursory and robustly diagnostic of an impending incident. Since mild screen-out could be useful in increasing the net pressure in the driven fracture and thereby enhance the stimulated volume of the reservoir (Massaras and Massaras 2012;E. Dontsov and Peirce 2015), the definition of screen-out is first constrained into the most critical level where fracturing operations are suspended in the open well by the release of pressure and cleaning of the wellbore is mandated.…”

“…Dontsov and Peirce 2015), the definition of screen-out is first constrained into the most critical level where fracturing operations are suspended in the open well by the release of pressure and cleaning of the wellbore is mandated. The determining-element mechanisms of screen-out are proposed and used to redefine and label the screen-out probability, which considers a greater number and broader variety of influence factors compared with previous efforts that have mainly relied on pressure interpretation or proppant accumulation (Massaras and Massaras 2012;Cai et al 2017). The pump rate, one of the determining elements, is fitted for the safest value where the probability of screen-out approaches the minimum.…”

Screenout Detection and Avoidance

“…Massaras et al [11] also developed the proprietary Screenout Index (SOI) technique which is a specialized version of the MR technique used when the SDT is not performed as per the prescribed four equal-steps procedure. Due to the need for a rapid Real-time (RT) in-mainfrac SD technique, Massaras et al [12] developed the Inverse Slope (IS) technique, which uses smart tangent lines for data trend visualization on the surface pressure plot. The moment the surface pressure starts to deviate from the tangent line on the Inverse Slope it marks the start of a SO downhole.…”