Mechanical Characterization of Low Permeable Siltstone under Different Reservoir Saturation Conditions: An Experimental Study
Hydro-fracturing is a common production enhancement technique used in unconventional reservoirs. However, an effective fracturing process requires a precise understanding of a formation’s in-situ strength behavior, which is mainly dependent on the formation’s in-situ stresses and...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2018-12-01
|
| Series: | Energies |
| Subjects: | |
| Online Access: | http://www.mdpi.com/1996-1073/12/1/14 |
| _version_ | 1811263319766466560 |
|---|---|
| author | Ayal Wanniarachchi Ranjith Pathegama Gamage Qiao Lyu Samintha Perera Hiruni Wickramarathne Tharaka Rathnaweera |
| author_facet | Ayal Wanniarachchi Ranjith Pathegama Gamage Qiao Lyu Samintha Perera Hiruni Wickramarathne Tharaka Rathnaweera |
| author_sort | Ayal Wanniarachchi |
| collection | DOAJ |
| description | Hydro-fracturing is a common production enhancement technique used in unconventional reservoirs. However, an effective fracturing process requires a precise understanding of a formation’s in-situ strength behavior, which is mainly dependent on the formation’s in-situ stresses and fluid saturation. The aim of this study is to identify the effect of brine saturation (concentration and degree of saturation (DOS)) on the mechanical properties of one of the common unconventional reservoir rock types, siltstone. Most common type of non-destructive test: acoustic emission (AE) was used in conjunction with the destructive tests to investigate the rock properties. Unconfined compressive strength (UCS) and splitting tensile strength (STS) experiments were carried out for 78 varyingly saturated specimens utilizing ARAMIS (non-contact and material independent measuring system) and acoustic emission systems to determine the fracture propagation. According to the experimental results, the increase in degree of pore fluid saturation (NaCl ionic solution) causes siltstone’s compressive and tensile strengths to be reduced through weakening and breakage of the existing bonding between clay minerals. However, increasing NaCl concentration in the pore fluid generally enhances the compressive strength of siltstone through associated NaCl crystallization effect and actually reduces the tensile strength of siltstone through the corrosive influence of the NaCl ions. Moreover, results show that AE capture and analysis is one of the most effective methods to understand crack propagation behavior in rocks including the crack initiation, crack propagation, and final failure. The findings of this study are important for the identification of fluid saturation dependent in-situ strength conditions for successful hydro-fracturing in low permeable reservoirs. |
| first_indexed | 2024-04-12T19:42:30Z |
| format | Article |
| id | doaj.art-d12ec87922054af7a924f3b5301408a2 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-12T19:42:30Z |
| publishDate | 2018-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-d12ec87922054af7a924f3b5301408a22022-12-22T03:19:03ZengMDPI AGEnergies1996-10732018-12-011211410.3390/en12010014en12010014Mechanical Characterization of Low Permeable Siltstone under Different Reservoir Saturation Conditions: An Experimental StudyAyal Wanniarachchi0Ranjith Pathegama Gamage1Qiao Lyu2Samintha Perera3Hiruni Wickramarathne4Tharaka Rathnaweera5Deep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, AustraliaDeep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, AustraliaSchool of Geosciences and Info-physics, Central South University, Changsha 410012, ChinaDeep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, AustraliaDeep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, AustraliaDeep Earth Energy Laboratory, Department of Civil Engineering, Monash University, Building 60, Melbourne 3800, AustraliaHydro-fracturing is a common production enhancement technique used in unconventional reservoirs. However, an effective fracturing process requires a precise understanding of a formation’s in-situ strength behavior, which is mainly dependent on the formation’s in-situ stresses and fluid saturation. The aim of this study is to identify the effect of brine saturation (concentration and degree of saturation (DOS)) on the mechanical properties of one of the common unconventional reservoir rock types, siltstone. Most common type of non-destructive test: acoustic emission (AE) was used in conjunction with the destructive tests to investigate the rock properties. Unconfined compressive strength (UCS) and splitting tensile strength (STS) experiments were carried out for 78 varyingly saturated specimens utilizing ARAMIS (non-contact and material independent measuring system) and acoustic emission systems to determine the fracture propagation. According to the experimental results, the increase in degree of pore fluid saturation (NaCl ionic solution) causes siltstone’s compressive and tensile strengths to be reduced through weakening and breakage of the existing bonding between clay minerals. However, increasing NaCl concentration in the pore fluid generally enhances the compressive strength of siltstone through associated NaCl crystallization effect and actually reduces the tensile strength of siltstone through the corrosive influence of the NaCl ions. Moreover, results show that AE capture and analysis is one of the most effective methods to understand crack propagation behavior in rocks including the crack initiation, crack propagation, and final failure. The findings of this study are important for the identification of fluid saturation dependent in-situ strength conditions for successful hydro-fracturing in low permeable reservoirs.http://www.mdpi.com/1996-1073/12/1/14hydro-fracturingsiltstonecompressive strengthtensile strengthbrinestress–strainacoustic emission |
| spellingShingle | Ayal Wanniarachchi Ranjith Pathegama Gamage Qiao Lyu Samintha Perera Hiruni Wickramarathne Tharaka Rathnaweera Mechanical Characterization of Low Permeable Siltstone under Different Reservoir Saturation Conditions: An Experimental Study Energies hydro-fracturing siltstone compressive strength tensile strength brine stress–strain acoustic emission |
| title | Mechanical Characterization of Low Permeable Siltstone under Different Reservoir Saturation Conditions: An Experimental Study |
| title_full | Mechanical Characterization of Low Permeable Siltstone under Different Reservoir Saturation Conditions: An Experimental Study |
| title_fullStr | Mechanical Characterization of Low Permeable Siltstone under Different Reservoir Saturation Conditions: An Experimental Study |
| title_full_unstemmed | Mechanical Characterization of Low Permeable Siltstone under Different Reservoir Saturation Conditions: An Experimental Study |
| title_short | Mechanical Characterization of Low Permeable Siltstone under Different Reservoir Saturation Conditions: An Experimental Study |
| title_sort | mechanical characterization of low permeable siltstone under different reservoir saturation conditions an experimental study |
| topic | hydro-fracturing siltstone compressive strength tensile strength brine stress–strain acoustic emission |
| url | http://www.mdpi.com/1996-1073/12/1/14 |
| work_keys_str_mv | AT ayalwanniarachchi mechanicalcharacterizationoflowpermeablesiltstoneunderdifferentreservoirsaturationconditionsanexperimentalstudy AT ranjithpathegamagamage mechanicalcharacterizationoflowpermeablesiltstoneunderdifferentreservoirsaturationconditionsanexperimentalstudy AT qiaolyu mechanicalcharacterizationoflowpermeablesiltstoneunderdifferentreservoirsaturationconditionsanexperimentalstudy AT saminthaperera mechanicalcharacterizationoflowpermeablesiltstoneunderdifferentreservoirsaturationconditionsanexperimentalstudy AT hiruniwickramarathne mechanicalcharacterizationoflowpermeablesiltstoneunderdifferentreservoirsaturationconditionsanexperimentalstudy AT tharakarathnaweera mechanicalcharacterizationoflowpermeablesiltstoneunderdifferentreservoirsaturationconditionsanexperimentalstudy |