Proppant Distribution in Multistage Hydraulic Fractured Wells: A Large-Scale Inside-Casing Investigation

Abstract

Effectively stimulating multiple pay zones using separate fracturing treatments can be costly and time consuming. By contrast, multistage fracturing is a widely used technique that offers the advantage of stimulating significant portions of the reservoir by fracturing through multiple perforations simultaneously. While the multistage fracturing method known as "plug and perf" has been proven to be an effective method for developing unconventional resources, it presents the challenge of achieving even proppant distribution to all perforation clusters during each stimulation stage.It is commonly assumed that the plug and perforate multistage fracturing technique provides the planned fluid and proppant distribution among the fractures that are simultaneously taking fluid during pumping a single stage. However, parameters, such as the reservoir properties, fluid rheology, and proppant characteristics have demonstrated a strong influence on the actual proppant and fluid distribution into the various perforations.Field data indicates, in many cases, that some of the clusters do not contribute to production. This indication supports the hypothesis that actual proppant and fluid distribution along the stimulated clusters might be different from the assumed uniform distribution. Some believe that the amount of proppant appears to be heavily weighted toward the end of the perforated interval, which results in uneven proppant distribution. Empirical data as well as laboratory tests have yet to be challenged against the few studies that exist. This paper presents a first-of-its-kind large-scale investigation that was conducted to study proppant distribution among separated perforations along a horizontal interval. These experiments closely simulate any single stage during the plug-andperforate fracturing process. The effect of various fluid specific gravities, fluid viscosities, proppant specific gravities, proppant sizes, and slurry flow rates were investigated while keeping outside-casing parameters constant. The various aspects of proppant and fluid flow through a perforated interval are discussed. The experimental efforts discussed in this paper create a better understanding of fluid and proppant behavior in this widely used fracturing process to help achieve maximum efficiency.

Transport and Distribution of Proppant in Multistage Fractured Horizontal Wells: A CFD Simulation Approach

“…A large-scale experimental study of proppant distribution among perforations (Crespo et al, 2013) was conducted simultaneously. Results show that the larger size and higher density proppant behaves differently (attributed to uneven enlargement of perforations, the 16/30-mesh sand test was not run).…”

“… Validation has been performed for proppant flow in three perforations against theoretical empirical formulas for pressure difference, and CFD results closely match empirical calculations.  A large-scale test model (Crespo et al 2013) has been simulated with CFD, and results were compared. The first case test results were in agreement with CFD results.…”

“…A series of CFD simulations were performed to explore the relative distribution of proppant while flowing through a set of perforations. The following modeling is to replicate the large scale physical model described in Crespo et al (2013). The flow rates and resulting fluid distributions to the three perforations in the CFD simulations are assigned to be the same as measured during that yard testing.…”

Pressure Transient Behavior of Horizontal Well with Time-Dependent Fracture Conductivity in Tight Oil Reservoirs

“…The pressure difference created during hydraulic fracturing allows the proppants to stay in the fractures away from the horizontal well heel [51], and as a result, the fracture conductivities are different that may further have an impact on the pressure behavior. Two scenarios of even and uneven proppant distribution can be seen as schematics in Figures 15(a) and 15(b), respectively, which are used to study the effect of proppant distribution.…”

Evaluation and Optimization of Proppant Distribution in Multistage Fractured Horizontal Wells: A Simulation Approach

“…With modeling with all perforations being mechanically equal, when proppant carried by fracturing fluid at a high velocity is forced to change flow direction (i.e., through perforations in casing), the difference in the specific gravity (SG) between the proppant and the fracturing fluid causes most of the proppant to concentrate toward the center of the fluid path and therefore a higher proportion can reach the furthermost (i.e., toward the toe) perforated interval, while the upper perf intervals receive mostly proppant-free "clean" fluid or less proppant than intended. Jain et al (2013) presented a first-of-its-kind large-scale, yard testing investigation conducted to understand proppant distribution among perforated clusters. and Deshpande et al (2013) conducted a CFD study to understand transport and distribution of proppant in multistage-fractured horizontal wells.…”