Optimizing Fracturing Fluid Cleanup in the Bossier Sand Using Chemical Frac Tracers and Aggressive Gel Breaker Deployment

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractProper fluid and proppant placement are critical to a successful propped fracture stimulation treatment. Despite effective placement of the treatment, well performance is often detrimentally affected by incomplete gel breaking and fluid recovery. A technique employing a family of environmentally friendly, fracturing fluid compatible chemical tracers has been employed for quantifying segment-by-segment fracturing fluid recovery. Utilizing this technology, it is demonstrated that individual fluid segment cleanup and recovery can be enhanced by optimizing fracturing fluid selection and by using aggressive gel breaker deployment schemes. The validation of improvements in fracturing fluid cleanup and the resultant effects on well performance are presented using Bossier Sand case histories.Comparisons between crosslinked gel systems and between conventional and aggressive gel breaker deployment schemes are highlighted.

Understanding Flowback as a Transient 2-Phase Displacement Process: An Extension of the Linear Dual-Porosity Model

“…Among existing flowback chemical analysis models (Asadi et al, 2008;Sullivan et al, 2004;Willberg et al, 1998;Woodroof et al, 2003), Gdanski et al (2007) was on of the first to incorporate a chemistry layer to a 2-D numerical simulator. This simulator was used to history-match the composition of flowback fluid.…”

“…This calls for a model that captures the transient 2-phase (gas/oil + water) flow in HF, and can be used for history matching rate and pressure data measured during flowback operations. Flowback chemical (tracer) analysis (Asadi et al, 2008;Sullivan et al, 2004;Willberg et al, 1998;Woodroof et al, 2003) could provide (1) an efficient means of differentiating formation water from flowback water (fracturing fluid + formation water) and (2) an optimal fracture clean-up or load recovery workflow.Developing an appropriate model for analysing rate/pressure measured during flowback operation requires a proper review of the static framework and flow physics of existing unconventional reservoir models. This paper extends the existing linear dual-porosity model (DPM) and develops a flowback analysis model (FAM) which accounts for transient multiphase flow in HF.…”

“…This model assumes that water-saturation drop with time causes a corresponding non-linear increase in hydrocarbon relative-permeability in HF. The application and drawbacks of these methods are discussed below.Among existing flowback chemical analysis models (Asadi et al, 2008;Sullivan et al, 2004;Willberg et al, 1998;Woodroof et al, 2003), Gdanski et al (2007) was on of the first to incorporate a chemistry layer to a 2-D numerical simulator. Fifteen tight oil, tight gas and shale gas wells completed in the Bluesky, Cardium, Evie, Muskwa and Otter-Park Formations were used for this study.…”

Modeling Gel Break-Time in Gravel Pack Fluids as a Function of Breaker and Activator Concentrations with Temperature

“…After a gravel pack job, flowback is carried out as soon as possible. Any gel, particularly crosslinked gels which are most damaging [8] that remains in the formation can cause formation damage by reducing the permeability of the newly placed proppant placed in the near wellbore region. Bacteria in the formation can use the gel (mostly organic polymers) as energy source and multiply, producing slime that equally reduces formation permeability.…”

“…Some studies have demonstrated that viscous properties of gels are controlled by their network structure [10]. Bleach has been used as a breaker in the prepad [8]. During flow back the bleach flowed into the area where the cross-linked gel was pumped to complement the action of the conventional breaker used in the gel, without compromising the proppant placement.…”