APPLICATION OF ABANDONED MINE DRAINAGE FOR REUSE OF MARCELLUS SHALE FLOWBACK WATER: WASTEWATER AND SOLID WASTE MANAGEMENT by Can He Bachelor of Engineering, Harbin Institute of Technology, 2011 Master of Science, Carnegie Mellon University, 2012 Submitted to the Graduate Faculty of Swanson School of Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy University of Pittsburgh 2015 i UNIVERSITY OF PITTSBURGH SWANSON SCHOOL OF ENGINEERING This dissertation was presented by Can He It was defended on November 19, 2015 and approved by Radisav D. Vidic, Ph.D., Professor, Department of Civil and Environmental Engineering Gregory V. Lowry, Ph.D., Professor, Department of Civil and Environmental Engineering at Carnegie Mellon University Leonard W. Casson, Ph.D., Associate Professor, Department of Civil and Environmental Engineering Leanne M. Gilbertson, Ph.D., Assistant Professor, Department of Civil and Environmental Engineering Dissertation Director: Radisav D. Vidic, Ph.D., Professor, Department of Civil and Environmental Engineering ii Copyright © by Can He 2015 iii APPLICATION OF ABANDONED MINE DRAINAGE FOR REUSE OF MARCELLUS SHALE FLOWBACK WATER: WASTEWATER AND SOLID WASTE MANAGEMENT Can He, Ph.D. University of Pittsburgh, 2015 Marcellus Shale play, underlying 70% of Pennsylvania, is the largest onshore shale gas reservoir in United States. Recent advancements in horizontal drilling and multi-stage hydraulic fracturing technologies enabled economical recovery of unconventional (shale) natural gas resource and greatly expanded natural gas production in the United States. Flowback water generated during shale gas extraction in Pennsylvania typically contains high concentrations of total dissolved solids (TDS), heavy metals (e.g., Ba and Sr), and naturally occurring radioactive materials (NORMs), which raises significant public concerns and environmental challenges related to wastewater management. Due to limited capacity for wastewater disposal by deep well injection in Pennsylvania, flowback water is generally reused for hydraulic fracturing. As only 10-30% of hydraulic fracturing fluid is recovered, large volume of make-up water is required to support hydraulic fracturing of new wells. Abandoned mine drainage (AMD) is an environmental legacy from coal mining industry and one of the most serious threats to water quality in Pennsylvania. Application of AMD for reuse of Marcellus Shale flowback water has never been tried by the unconventional gas industry before. Key technical barriers include compatibility of the treated water with fracturing chemicals and management of radioactive solid waste generated iv from this practice. This study employs laboratory and pilot-scale systems to demonstrate the feasibility of this approach for flowback water reuse and to elucidate the underlying fundamental mechanisms as well as develop engineering solutions to implement this management strategy. Laboratory studies evaluated the kinetics and equilibrium of precipitation reactions that occur when flowback water and AMD are mixed. Sulfate removal through mixing flowback water and AMD is governed by barite (BaSO ) precipitation and chemical equilibrium can be 4 predicted thermodynamic models with Pitzer’s equation for activity corrections. An empirical model was developed to predict the kinetics of barite precipitation. Celestite (SrSO ) 4 precipitation requires over 10 hours to reach equilibrium and does not contribute significantly to the control of sulfate concentration in the finished water due to kinetic limitations in the treatment plant. The feasibility of using microfiltration to separate particulate matter that is originally present in the wastewaters or that is created through mixing flowback water and AMD, was studied using both dead-end and cross-flow filtration systems. Early flowback water can cause severe membrane fouling due to the presence of stable submicron colloidal particles. Floc breakage is a key factor that may cause severe permeate flux decline during filtration of the flowback water that does not contain such colloidal particles. A pilot-scale system was used to demonstrate the feasibility of co-treatment of flowback water and AMD. The finished water from this treatment process can be adjusted to meet the criteria for unrestricted use in hydraulic fracturing operations. The barite particles generated in this process have high radium content due to coprecipitation of radium with barium sulfate. The pilot-scale study revealed that sludge recycling could enable the use of Ra-enriched barite particles recovered from this process as a weighting agent in drilling mud formulation. v Impact of antiscalants on the fate of barium sulfate that may be formed in unconventional gas wells was also evaluated in this study. Antiscalants are unlikely to prevent formation of barite particles because of high supersaturation levels that are typical in unconventional gas extraction. When the fracturing fluid is rich in sulfate, barite particles will inevitably form in the subsurface and may be transported through the proppant pack during the flowback period. While most common antiscalants cannot act as threshold inhibitors for barite formation, they can enhance the mobility of barite particles through proppant pack by limiting the size of barite particle and providing steric repulsion at high ionic strength condition. The key finings of this study indicate that it is feasible to utilize AMD as a make-up water source for flowback water reuse. The co-treatment process demonstrated in this study offers an alternatively approach for the management of flowback water generated in Pennsylvania. vi TABLE OF CONTENTS TABLE OF CONTENTS ......................................................................................................... VII LIST OF TABLES .................................................................................................................... XII LIST OF FIGURES ................................................................................................................. XIII ACKNOWLEDGEMENT ..................................................................................................... XVII 1.0 INTRODUCTION ................................................................................................................. 1 1.1 RESEARCH OBJECTIVES ......................................................................................... 4 1.2 SCOPE OF THE DISSERTATION ............................................................................. 5 2.0 USE OF ABANDONED MINE DRAINAGE FOR THE DEVELOPMENT OF UNCONVENTIONAL SHALE GAS RESOURCES ......................................................... 8 2.1 INTRODUCTION .......................................................................................................... 9 2.2 UNCONVENTIONAL SHALE GAS EXTRACTION ............................................. 10 2.3 ABANDONED MINE DRAINAGE ........................................................................... 14 2.4 CO-TREATMENT OF FLOWBACK WATER AND AMD ................................... 15 2.5 CONCERNS REGARDING AMD USE IN UNCONVENTIONAL GAS EXTRACTION ............................................................................................................. 18 2.5.1 Compatibility with hydraulic fracturing chemical additives .......................... 18 2.5.2 Impact on well productivity ............................................................................... 19 2.5.3 Potential for bacterial activity ........................................................................... 20 2.5.4 Management of solid wastes ............................................................................... 21 2.5.5 Regulatory concerns ........................................................................................... 24 vii 2.6 TREATMENT PROCESSES AFTER MIXING AMD AND FLOWBACK WATER………………………………………………………………………………. 26 2.7 SUMMARY AND CONCLUSION ............................................................................. 28 3.0 MANAGEMENT OF MARCELLUS SHALE PRODUCED WATER IN PENSYLVANIA: A REVIEW OF CURRENT STRATEGIES AND PERSPECTIVES ............................................................................................................................................... 30 3.1 INTRODUCTION ........................................................................................................ 31 3.2 STATE OF THE ART ................................................................................................. 33 3.2.1 Flowback water management ............................................................................ 33 3.2.2 NORM in Marcellus Shale produced water ..................................................... 37 3.3 PERSPECTIVE ............................................................................................................ 41 3.3.1 Co-treatment of produced water and AMD ..................................................... 41 3.3.2 Fate of Radium during co-treatment of produced water and AMD .............. 46 3.3.3 Alternative management approach for produced water in Pennsylvania ..... 48 3.4 SUMMARY AND CONCLUSIONS ........................................................................... 51 4.0 EQUILIBRIUM AND KINETICS OF CHEMICAL REACTIONS PROMOTED BY THE USE OF AMD FOR FLOWBACK WATER TREATMENT AND REUSE ........ 53 4.1 INTRODUCTION ........................................................................................................ 54 4.2 MATERIALS AND METHOD ................................................................................... 56 4.2.1 Flowback water and AMD sampling ................................................................ 56 4.2.2 Empirical kinetic model for barite precipitation ............................................. 57 4.3 RESULTS AND DISCUSSION ................................................................................... 58 4.3.1 Mixing experiments and equilibrium prediction ............................................. 58 4.3.2 Kinetics model for BaSO4 precipitation ............................................................ 61 4.3.3 Empirical kinetic model for barite precipitation ............................................. 64 4.4 SUMMARY AND CONCLUSIONS ........................................................................... 68 viii 5.0 MICROFILTRATION IN RECYCLING OF MARCELLUS SHALE FLOWBACK WATER: SOLIDS REMOVAL AND POTENTIAL FOULING MECHANISM ........ 69 5.1 INTRODUCTION ........................................................................................................ 70 5.2 MATERIALS AND METHODS................................................................................. 73 5.2.1 Feed water............................................................................................................ 73 5.2.2 Membrane filtration experiment ....................................................................... 76 5.2.3 Fouling mechanism identification ..................................................................... 76 5.2.4 Stability evaluation ............................................................................................. 77 5.3 RESULTS AND DISCUSSION ................................................................................... 77 5.3.1 Membrane filtration of mixture of AMD and flowback water ....................... 77 5.3.2 Membrane fouling analysis ................................................................................ 80 5.3.3 Stability of colloidal suspension ......................................................................... 86 5.4 SUMMARY AND CONCLUSIONS ........................................................................... 89 6.0 APPLICATION OF MICROFILTRATION FOR THE TREATMENT OF MARCELLUS SHALE FLOWBACK WATER: INFLUENCE OF FLOC BREAKAGE ON MEMBRANE FOULING .................................................................... 91 6.1 INTRODUCTION ........................................................................................................ 92 6.2 MATERIALS AND METHODS................................................................................. 95 6.2.1 Characteristics of flowback water ..................................................................... 95 6.2.2 Filtration experiments ........................................................................................ 96 6.2.3 Membrane cleaning procedure .......................................................................... 97 6.2.4 Fouling mechanism modeling ............................................................................ 98 6.2.5 Characterization of floc strength ....................................................................... 99 6.3 RESULTS AND DISCUSSION ................................................................................. 100 6.3.1 Cross-flow filtration experiments .................................................................... 100 6.3.2 Fouling mechanism identification ................................................................... 102 ix 6.3.3 Impact of floc breakage on membrane fouling .............................................. 105 6.4 SUMMARY AND CONCLUSIONS ......................................................................... 109 7.0 UTILIZATION OF ABANDONED MINE DRAINAGE FOR MARCELLUS SHALE FLOWBACK WATER REUSE: A PILOT STUDY ...................................................... 111 7.1 INTRODUCTION ...................................................................................................... 112 7.2 MATERIALS AND METHODS............................................................................... 114 7.2.1 Characteristics of flowback water and AMD ................................................. 114 7.2.2 Bench-scale tests ................................................................................................ 116 7.2.3 Pilot-scale operation.......................................................................................... 117 7.2.4 Analytical methods............................................................................................ 118 7.3 RESULTS AND DISCUSSION ................................................................................. 120 7.3.1 Sulfate removal.................................................................................................. 120 7.3.2 AMD as a source of coagulant ......................................................................... 123 7.3.3 Sustainable management of Ra-enriched solid waste .................................... 125 7.4 SUMMARY AND CONCLUSIONS ......................................................................... 130 8.0 IMPACT OF ANTISCALANTS ON THE FATE OF BARITE IN THE UNCONVENTIONAL WELLS ....................................................................................... 132 8.1 INTRODUCTION ...................................................................................................... 133 8.2 MATERIALS AND METHODS............................................................................... 135 8.2.1 Chemical reagents ............................................................................................. 135 8.2.2 Preparation and characterization of BaSO4 particles ................................... 136 8.2.3 Column experiments ......................................................................................... 137 8.3 RESULTS AND DISCUSSION ................................................................................. 138 8.3.1 Characterization of BaSO4 particles ............................................................... 138 8.3.2 Mobility of bare BaSO4 through proppant sand media ................................ 143 x