FAST

The Fracturing, Acidizing, Stimulation Technology Consortium

Projects

The projects undertaken by FAST are determined by a member voting process. Although the projects are numbered and labeled individually, several of them have overlapping components. Consortium members are encouraged to lend their expertise to projects that specifically interest them and work closely with the students. We currently have ongoing projects that were voted in during Phase 1, Phase 2, and Phase 3 balloting. New phases (and associated projects) are initiated as projects are completed and funding allows.

Current FAST projects include:

Project #1: Hydraulic fracture height growth and containment mechanisms
Although significant advances have been made during the past two decades in mapping hydraulic fracture geometric growth, the reasons for certain growth characteristics remain ambiguous. One of the most significant components of this propagation behavior is height containment-or lack there of. With the advent of microseismic mapping and the associated generation of shear waves during fracture treatments, we now recognize that not only do fractures exhibit tensile failure, but also shear failure which has a significant effect on fracture propagation. These failure types, how they work, and their importance are the objectives of this project. This project is currently in its third phase.

Project #2: Non-Darcy flow effects
Proppant pack conductivity can be significantly reduced by many factors, including non-Darcy and multiphase flow characteristics. These effects can account for a significant portion of the disparity between propped fracture half-length and the effective flow capacity of a given fracture. Historically, non-Darcy flow effects have been considered a high rate issue, but this is not always the case and can severely affect the conductivity and productivity of hydraulic fractures in all well cases. The objective of this project is to further the understanding of non-Darcy and multiphase flow effects, specifically in hydraulic fractures. This project is currently in its second phase.

Project #3: Hydraulic fracture reorientation
This project focuses on production and reserve recovery from multiple hydraulic fractures in an anisotropic tight-gas reservoir with limited areal extent. In continuous, blanket type reservoirs, fracturing with reorientation or creating multiple fracture in a horizontal well has proved very beneficial to field development and reserve recovery. This project expands this concept to more complex depositional environments found in many tight-gas reservoirs. It is investigating if there is any benefit to creating and producing from multiple fractures in a bounded and relatively small reservoir extent.

Project #4: Coal bed methane stimulation
Coal bed methane (CBM) production has steadily evolved from being considered an unconventional hydrocarbon production technique into a more conventional practice which plays a part in numerous company portfolios. During the last several decades, reservoir engineering components of CBM production have made significant advances. Unfortunately, during the same time, stimulation of CBM reservoirs has largely remained a secondary consideration with treatment designs being based on sandstone reservoir designs and modified as necessary for coals. This project focuses on various aspects of CBM stimulation.

Project #7: Slickwater fracture treatments
Why do slickwater hydraulic fractures work in some areas and not others? Why do slickwater hydraulic fracture treatments work at all? What are the characteristics that make a reservoir a good candidate in which to attempt a slickwater treatment? These are all questions that are asked by stimulation engineers evaluating the possibility of using slickwater in their fields, unfortunately the answers are not easy to reach. A variety of reasons for slickwater's success are suggested by industry personnel including minimization of gel residue and activation of geological discontinuities (natural fractures, bedding planes, etc.) but no solid conclusions are available. This project focuses on evaluation of slickwater fracturing treatments and the reasons for success or failure in various situations. This project is currently in its second phase.

Project #10: Stimulation of horizontal wells
The focus of this project is to investigate the "stress shadowing" behaviors observed when pumping multiple fracturing treatments in a horizontal well. This is a rock mechanical, three-dimensional stress state issue, and the project includes a finite element modeling component. The intent of the project will be to determine if the extent of the stress envelopes can be predicted and/or controlled to aid in treatment placement.

Project #11: Formation face fracturing damage and gel clean-up processes
This project aims to further knowledge in formation face damage and gel cleanup mechanisms, two principal factors that impair effectiveness of a hydraulic fracturing treatment. It is reviewing existing models and to expanding those models to a more comprehensive one that includes known and validated relationships for relative permeability effects, capillary pressure effects, and fracturing fluids' yield stress effects. It includes laboratory work to validate some of the assumptions, to evaluate and fine tune the numerical model, and to determine experimental relationships between variables in the model.

Project #15: Surface monitoring of hydraulic fractures
This project focuses on evaluating the use of surface microseismic monitoring of hydraulic fractures. A detailed data set has been acquired and includes various log suites; cross-well seismic; surface seismic monitoring of eight fracture stages; and fracturing treatment data. The thoroughness of the data set will allow for a variety of analyses, however, initial focus will be placed on characterizing the fluvial system in the treated area and the associated hydraulic fracture growth from a three-dimensional viewpoint.

Project #16: Shale Rock Mechanical Properties and Damage Mechanisms
No two shale systems are the same and most treat very differently. In fact, most “shales” are actually siltstones with significant quartz components. Other ongoing research at the Colorado School of Mines is showing that the rock mechanical properties in shales are significantly affected by the mineralogy and kerogen content. This project focuses on the effect of these rock mechanical property impacts on hydraulic fracturing components including the effects on areas such as embedment of proppants and potential “weakening” of the rock frame by stimulation fluids.

Project #18: Matrix Imbibition of Shale Gas Reservoirs
This project focuses on the imbibition of hydraulic fracturing fluids in shale reservoirs. Such a phenomenon has major implications for matrix relative permeability and will greatly affect reservoir simulation and rate transient analysis. Better quantification and understanding of matrix (and microfracture) imbibition could greatly improve post-treatment reservoir modeling and analysis.

Project #19: Determination of Correct Multiphase Correlations for BHP Calculations
There are a variety of correlations developed for BHP calculations for wells producing gas, oil and water. Many of these correlations work well for a give situation, however, if the wrong correlation is chosen, errors can be extremely large. This project focuses on developing and training a neural network system to correctly select a given correlation for a given situation. A major outcome of this work is improved post-treatment production data analysis (RPI, GPA, etc.).

Project #20: Determination of Well Clean Up Characteristics Through Produced Fluid/Solids Analysis
Improving the understanding of fracturing fluid clean up processes is of key interest to industry and is a critical component to maximizing the production and reserve recovery in unconventional reservoirs. This project focuses on developing and populating a fracture clean up database that includes water chemistry, solids analysis, flow rates, and production methods and develops relationships between cleanup parameters and key stimulation design parameters using statistical methods.

Project #21: Proppant Transport in Complex Fracture Systems
Proppant transport has been studied in single slot (fracture) systems in the laboratory. This project takes such work a step farther by using complex slot systems with various angles. Transport into these secondary and tertiary systems is studied using a variety of fracturing fluids. This project is currently in its third phase.

Project #22: Application of Pump-Shutdown Signals as a Fracture Diagnostic Tool
DFIT's, step rate tests, and other pressure analysis techniques supply a tremendous amount of information about treatment and reservoir characteristics. This project seeks to extend pressure analysis by looking at high frequency pressure data after stage completion. Not only is information being sort in regards to the completion efficiency, but also analysis of the geologic setting is being incorporated.

 

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