Experimental Investigation of Propped Fracture Conductivity in Tight Gas Reservoirs Using Factorial Design

Awoleke, Obadare O.; Romero, Jose Domingo; Zhu, Ding; Hill, D.

doi:10.2118/151963-ms

Cited by 13 publications

(3 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Experimental Design (ED) has been used in diverse areas such as aerospace, civil engineering and electronics for analysis and optimization of complex, nonlinear systems described by computer models (Parikh, 2003). Experimental designs have also been used in petroleum engineering studies (Awoleke et al, 2012;Segnini et al, 2014; Ambastha 2014; Yu and Sepehrnoori 2014).…”

Section: Post-treatment Evaluationmentioning

confidence: 99%

Using experimental design and response surface methodology to model induced fracture geometry in Shublik shale

Poludasu

2016

Journal of Unconventional Oil and Gas Resources

View full text Add to dashboard Cite

The Triassic Shublik Formation of the Alaska North Slope is a world-class resource rock and has been identified as the major source of many of the conventional hydrocarbon accumulations on the North Slope, including Prudhoe Bay. Recent interest in the Shublik as a potential shale resource play has highlighted the need for robust hydraulic fracture modeling and simulation of the interval, but little geologic information is available because of the remote nature of the region and the complex character of the Shublik. In this study, a methodology was developed for identifying the critical variables needed for accurate planning of a hydraulic fracturing treatment in a play like the Shublik where much of the geology remains unconstrained. These identified critical variables can be used to develop a proxy model that can be used in lieu of a numerical simulator.This study was conducted in two stages. The first stage used 2-level fractional factorial design to identify the statistical significance of the input variables on the simulated fracture geometry. This stage was conducted in three phases, each phase incorporating progressively more complex assumptions about geology. Using the three most significant variables identified from first stage, the second stage of this study applies Box-Behnken experimental design and response surface methodology for quantifying functional relationships between input variables and the predicted fracture geometry. A pseudo 3D numerical simulator (Fracpro PT) and MATLAB were used to develop proxy models. These proxy models, typically a polynomial equation, are an easier alternative to Fracpro PT and can predict the fracture geometry with very less computational time.The use of experimental design drastically reduces the number of simulations required to evaluate large number of variables. With only 137 simulations, 26 variables were ranked based on their statistical significance and a non-linear proxy model was developed. Predicted values of the fracture geometry obtained using the proxy models were in good agreement with the simulated values of the fracture geometry (R 2 value of 99.39% for fracture length, R 2 value of 99.54% for fracture height and R 2 value of 98.17% for fracture width).

show abstract

Section: Post-treatment Evaluationmentioning

confidence: 99%

Using experimental design and response surface methodology to model induced fracture geometry in Shublik shale

Poludasu

2016

Journal of Unconventional Oil and Gas Resources

View full text Add to dashboard Cite

show abstract

“…The commonest application is to use a modified API conductivity cell to accommodate 3 times thicker samples to account for fluid leakoff through the sample during the 2 experiment. Instead of flowing 2% KCl through the fracture as specified by ISO standards, the modified tests can flow dry gas, wet gas, fresh water, brine of various concentrations and multi-phase flow for different reasons, such as protecting the shale sample by flowing dry nitrogen (Zhang et al 2013; Zhang et al 2015), keeping the gel hydrated by wet gas (Awoleke et al 2012), studying the water sensitivity (Conway et al 2011), and investigating the effect of multiphase flow and non-Darcy flow (Barree et al 2009). Both cylindrical core plugs and samples of API dimensions (7 inch long, 1.5 inch wide with curved ends) are used in the non-ISO tests (Ramurthy et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Development of new testing procedures to measure propped fracture conductivity considering water damage in clay-rich shale reservoirs: An example of the Barnett Shale

Zhang

Kamenov

Zhu

et al. 2015

Journal of Petroleum Science and Engineering

View full text Add to dashboard Cite

Multi-stage hydraulic fracturing is the key to the success of many shale gas and shale oil reservoirs. The main objective of hydraulic fracturing in shale is to create fracture networks with sufficient fracture conductivity. Due to the variation in shale mineralogical and mechanical properties, fracture conductivity damage mechanisms in shale formations are complex. Standard fracture conductivity measurement procedures developed for fractures with high proppant concentration had to be modified to measure the conductivity in fractures with low proppant concentration. Water-based fracturing fluids can interact with the clay minerals in shale and eventually impact shale fracture conductivity. All these challenges require more experimental studies to improve our understanding of realistic fracture conductivity in shale formations.The aims of this work were to design an experimental framework to measure fracture conductivity created by low concentration proppants and to investigate the mechanisms of conductivity damage by water. We first presented the laboratory procedures and experimental design that can accurately measure fracture conductivity of shale fractures at low concentrations of proppants. Then we measured the undamaged shale fracture conductivity by dry nitrogen. Water with similar flowback water compositions was injected to simulate the damage process followed by secondary gas flow to measure the recovered fracture conductivity after the water damage.This study shows that the developed laboratory procedures can be utilized to reproducibly measure shale fracture conductivity by both gas and liquid. The conductivity measurement of propped fractures by small size proppants at low concentrations requires strict control on gas flow bypassing the fracture both parallel and perpendicular to the fracture length direction. Shale fracture surface softening is identified as the dominant cause for the significant conductivity reduction after water flow.

show abstract

“…They matched the predicted results with experimental results by introducing a number of empirical coefficients. A new fracture conductivity correlation was proposed by Awoleke et al (2012) using factorial design. This correlation links facture conductivity with proppant concentration, temperature, closure stress and gel loading.…”

Section: Introductionmentioning

confidence: 99%

A new theoretical method to calculate shale fracture conductivity based on the population balance equation

Zhang

Zhu

Hill

2015

Journal of Petroleum Science and Engineering

View full text Add to dashboard Cite

a b s t r a c tShale fracture conductivity plays a critical role in determining the long term production of shale wells. High fracture conductivity is achieved by pumping more proppants and minimizing conductivity damage by fracturing fluid. Currently, fracture conductivity is either measured in laboratory following ISO 13503-5 or calculated using correlations derived from extensive laboratory tests by regression analysis. There is a need for a handy and practical tool to calculate shale fracture conductivity reflecting realistic fracturing designs.This paper presents a new correlation to calculate shale fracture conductivity that considers proppant properties, fracture design variables and formation mechanical properties. This correlation is based on the population balance equation for size reduction. It utilizes the population balance concept to predict the crushed proppant size distribution under increasing closure stress. Numerical solution of the integrodifferential equation is validated by comparing the computed results with the measured data. The crushed grain size distribution determines the permeability of the sand pack. Fracture width is calculated separately by considering proppant embedment and proppant grain rearrangement. Fracture conductivity is then calculated and compared with laboratory measured conductivity. Finally, the effect of water damage to shale fracture conductivity is considered by bringing in a new modification term.Results show that the population balance equation can reasonably predict the crushed proppant size reduction by properly choosing the selection equation and breakage equation. The calculated shale fracture conductivity can match with the measured fracture conductivity using the Barnett Shale. An exponential expression can be used to account for the water damage effect in the Barnett Shale.

show abstract

Experimental Investigation of Propped Fracture Conductivity in Tight Gas Reservoirs Using Factorial Design

Cited by 13 publications

References 11 publications

Using experimental design and response surface methodology to model induced fracture geometry in Shublik shale

Using experimental design and response surface methodology to model induced fracture geometry in Shublik shale

Development of new testing procedures to measure propped fracture conductivity considering water damage in clay-rich shale reservoirs: An example of the Barnett Shale

A new theoretical method to calculate shale fracture conductivity based on the population balance equation

Contact Info

Product

Resources

About