Proppant Conductivity Consortium Introduction:

The Proppant Consortium for the investigation of the impact of fracturing fluids upon the conductivity of proppants was begun in 1986. Since then, the consortium has grown from 18 to 40 members. The consortium has four areas of study:

1. Determination of the long-term conductivity of proppants (baseline data).
2. The evaluation of the impact of fracturing fluid leakoff and damage upon proppant conductivity.
3. Determination of the impact of non-Darcy and multiphase flow on effective conductivity.
4. Evaluation of proppant flowback.

Baseline Data and Turbulence Factors:
In the baseline data, the consortium has produced a database of 50 proppants vs. type, size, concentration, closure, temperature and rock hardness. The baseline proppant data was originally placed in a program called PredictK. The program also has a series of equations to predict the conductivity with various frac fluids. In 2002 a new stand-alone windows based application of was created which includes more fundamental production predictions that were started in SL Frac. This version makes interacting with the Stim-Lab database of proppants more efficient and adds new capabilities to a continuously developing product. The new program achieves the objectives of combining PredictK, SL Frac and Cleanup.

Work is continuing to supplement conductivity and turbulence data for proppants with limited data. Methods are being investigated to determine the most effective method to generate turbulence data. New proppant supplier data will be added as data is generated and becomes available.

 Frac Fluid Cleanup Over 250 combinations of fluids, gel types, crosslinkers, and breakers at various temperatures and permeabilities have been evaluated. The data has been placed in a database that shows the retained conductivity vs. fluid type, temperature, breaker and core permeability.

At present, work continues in the investigation of cleanup vs. fluid type; rate and proppant concentration in an effort to define cleanup based on velocity rather than delta pressure to initiate flow. Low shear viscosity or yield point values, which have proved difficult to measure for broken gels, should be ideal to use in predicting if adequate reservoir energy exists to initiate cleanup in any particular part of the hydraulic fracture. At this point, we have not been able to identify a method that correlates with the observed cleanup with which to make these measurements. Simulators use velocity to iterate on fracture conductivity for beta factor and cleanup properties, given a created propped fracture length, proppant type and reservoir characteristics. Currently the simulation effort in PredictK specifies the maximum possible cleanup and looks at achievable velocities to estimate the expected degree of cleanup. Further investigation hopes to develop velocity cleanup curves for various fluid types.

Flowback of Proppant:
Proppant flowback evaluations have been extended to include gas and water at high closures vs. proppant size. The mechanical properties of proppant packs with and without resin coating are under investigation.

The objective is to develop an understanding of the principal factors controlling the flowback of proppant from hydraulic fractures. From a modeling standpoint, understanding a single flowing phase in base proppant and extending that understanding to the influence of cohesive factors such as surface tension in multiphase flow, flowback control additives and finally resin coated proppants are defined as the steps to achieving an effective model. The recent modeling effort is being guided by work by Professor Joseph at the University on Minnesota who has examined the movement of particles in thin fluids. Key experiments to confirm model predictions are currently in progress.

Donated Data:
A section in each consortium report is available for only consortium members to donate conductivity data accumulated by private testing at Stim-Lab. These studies have been funded privately, outside of the consortium program of funding. Most of these products are either new products being offered to the public, or are developmental products, which have been proved through extensive testing to be ready to market. These products are then added to the Predict K database. This becomes a value-added to the consortium members.

Benefits of membership:

• Full up-to-date characterization of available proppant products.
• Accurate and easy to use information incorporating proppants needed in fracture stimulation design.
• Interaction with broad-based industry membership regarding proppant technical issues.

Stim-Lab encourages new members so that research continues adding value to participating company's lines of business. Contact Us  for membership information.

Facts:

• Meetings held twice per year to discuss previous six month's studies
• Last twelve month's information available to members through website
• Previous data available to new members.