Experimental Investigation on the Dielectric Constant of Rocks with Low Porosity and Permeability

1997 ◽  
Vol 5 (01) ◽  
pp. 115-119 ◽  
Author(s):  
Wang Weinan ◽  
Zhang Xi ◽  
Geng Xiuwen ◽  
Chang Qingzhen
Keyword(s):  
Experimental Investigation ◽  
Dielectric Constant ◽  
Porosity And Permeability ◽  
Low Porosity

New results of Boda Claystone research: Genesis, mineralogy, geochemistry, petrophysics

2018 ◽  
Vol 482 (1) ◽  
pp. 75-92 ◽  
Author(s):  
Ferenc Fedor ◽  
Zoltán Máthé ◽  
Péter Ács ◽  
Péter Koroncz
Keyword(s):  
High Level Waste ◽  
Swelling Clays ◽  
Theoretical Approaches ◽  
Hydrodynamic Behaviour ◽  
Geological Formation ◽  
Porosity And Permeability ◽  
History Of ◽  
Surrounding Areas ◽  
High Level ◽  
Low Porosity

AbstractBoda Claystone is a very tight clayey rock with extreme low porosity and permeability, nano-size pores and small amounts of swelling clays. Due to this character it is ideal as a potential host rock for research into the possibilities of high-level waste deposition in geological formation. Though the research started more than 30 years ago, the genesis, the geotectonic history of the Boda Claystone Formation (BCF) and the geology of surrounding areas has only been sketched out recently. On the basis of research of the past few years the process of sedimentation of different blocks was able to be reconstructed. Equipment and methodological developments were needed for the investigation of reservoir geological and hydrodynamic behaviour of this rock, which began in the early 2000s. Based on them the pore structure and reservoir could be characterized in detail. Only theoretical approaches were available for the chemical composition of free porewater. Traditional water-extracting methods were not adaptable because of excessively low porosity and nano-scale pore size distribution. Hence, new ways have to be found for getting enough water for analysis. These new results of BCF research help to prepare more sophisticated and directed experiments, in which there is a great interest internationally.

Based on the Sedimentary Facies of the Low Porosity and Permeability Reservoir Water Flooded Layer Qualitative Interpretation Method

2015 ◽  
Vol 733 ◽  
pp. 47-50
Author(s):  
Mei Ling Zhang ◽  
Zheng Zhou ◽  
Lei Feng
Keyword(s):  
Research Method ◽  
Sedimentary Facies ◽  
Reservoir Water ◽  
Strong Basis ◽  
Qualitative Interpretation ◽  
Sand Body ◽  
Porosity And Permeability ◽  
Identification Chart ◽  
Interpretation Method ◽  
Low Porosity

Yushulin oilfield Fuyang reservoir belongs to typical low porosity and permeability reservoirs. The internal sand body has complex pore structure and serious heterogeneity. The well logging response doesn't change significantly after the reservoir is flooded. In order to improve the identification precision of the water flooded layer, this paper divides the reservoir into the thick reservoir which is mainly to fluvial facies and estuarine dam deposition and the thin and poor reservoir which is mainly to sheet sand and far sand dam two class. The qualitative identification chart of water flooded layer was established. The chart coincidence rate is more than 75 %, providing a strong basis for perforation scheme of infill wells. The research method of the peripheral oilfield flooded layer identification has wide applicability.

Observations of Tensile Fracturing of Anisotropic Rocks

SPE Journal ◽  
2016 ◽  
Vol 21 (04) ◽  
pp. 1289-1301 ◽  
Author(s):  
Saied Mighani ◽  
Carl H. Sondergeld ◽  
Chandra S. Rai
Keyword(s):  
Process Zone ◽  
Surface Topology ◽  
Breakdown Pressure ◽  
Rock Anisotropy ◽  
Fracturing Process ◽  
Stress Levels ◽  
Porosity And Permeability ◽  
Anisotropic Rocks ◽  
Loading Axis ◽  
Low Porosity

Summary Hydraulic fracturing is crucial to hydrocarbon recovery from resource plays and is essential to exploitation of geothermal energy. This process creates new tensile fractures and reactivates existing natural fractures, forming a highly conductive stimulated-reservoir volume (SRV) around the borehole. Although this process has been extensively studied and modeled for isotropic rock, only a limited number of studies have been performed for anisotropic rocks, such as shales, gneisses, and foliated granites. The fracturing process of anisotropic rocks such as shales is examined in this study. We divide the rock anisotropy into two anisotropic groups: conventional and veined. Two members of the conventional first group are Lyons sandstone, a brittle, quartz-dominated, low-porosity and -permeability, anisotropic (11%) material; and pyrophyllite, a monomineralic-clay-rich, strongly anisotropic (19%) metamorphic rock similar chemically and mechanically to shale with extremely low porosity and permeability. The second group consists of a suite of natural shale samples (18% anisotropy) from the Wolfcamp formation containing mineralized veins. Fracture initiation and propagation are studied during Brazilian tests. Strain gauges and acoustic-emission (AE) sensors record the deformation leading to and during failure. Scanning-electron-microscope (SEM) imaging and surface profilometry are used to study the post-failure fracture system and failed surface topology. Post-fracture permeability is measured as a function of effective stress. The influence of anisotropy on fracturing is investigated by rotating the sample-fabric direction relative to the loading axis through increments of 15°. The rock microstructure, lamination, and brittleness control the activation of the layers. Lyons sandstone shows a wide brittle fracture with larger process zone with twice as much layer activation at lower stress levels than pyrophyllite. The fracturing process in veined shale is, however, a coupled function of rock fabric and mineral veins. The veins easily activate at 15° orientation with respect to the loading axis at stress levels of 30% of the unveined-failure load. The resulting unpropped fracture has enhanced permeability by orders of magnitude. We suggest that fracturing from a deviated well reduces the breakdown pressure significantly (compared with a vertical well) and activates a large number of veins with enhanced conductivity without the need for excessive proppant.

scholarly journals Transient conduit permeability controlled by a shift between compactant shear and dilatant rupture at Unzen volcano (Japan)

2021 ◽  
Author(s):  
Yan Lavallée ◽  
Takahiro Miwa ◽  
James D. Ashworth ◽  
Paul A. Wallace ◽  
Jackie E. Kendrick ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Shear Zone ◽  
Damage Zone ◽  
Volcanic Eruptions ◽  
Shear Zones ◽  
Stick Slip ◽  
Anisotropic Permeability ◽  
Unzen Volcano ◽  
Porosity And Permeability ◽  
Low Porosity

Abstract. The permeability of magma in shallow volcanic conduits controls the fluid flow and pore pressure development that regulates gas emissions and the style of volcanic eruptions. The architecture of the permeable porous structure is subject to changes as magma deforms and outgasses during ascent. Here, we present a high-resolution study of the permeability distribution across two conduit shear zones (marginal and central) developed in the dacitic spine that extruded towards the closing stages of the 1991–1995 eruption at Unzen volcano, Japan. The marginal shear zone is approximately 3.2 m wide and exhibits a 2-m wide, moderate shear zone with porosity and permeability similar to the conduit core, transitioning into a ~1-m wide, highly-sheared region with relatively low porosity and permeability, and an outer 20-cm wide cataclastic fault zone. The low porosity, highly-sheared rock further exhibits an anisotropic permeability network with slightly higher permeability along the shear plane (parallel to the conduit margin) and is locally overprinted by oblique dilational Riedel fractures. The central shear zone is defined by a 3-m long by ~9-cm wide fracture ending bluntly and bordered by a 15–40 cm wide damage zone with an increased permeability of ~3 orders of magnitude; directional permeability and resultant anisotropy could not be measured from this exposure. We interpret the permeability and porosity of the marginal shear zone to reflect the evolution of compactional (i.e., ductile) shear during ascent up to the point of rupture, estimated by Umakoshi et al. (2008), at ~500 m depth. At this point the compactional shear zone would have been locally overprinted by brittle rupture, promoting the development of a shear fault and dilational Riedel fractures during repeating phases of increased magma ascent rate, enhancing anisotropic permeability that channels fluid flow into, and along, the conduit margin. In contrast, we interpret the central shear zone as a shallow, late-stage dilational structure, which partially tore the spine core with slight displacement. We explore constraints from monitored seismicity and stick-slip behaviour to evaluate the rheological controls, which accompanied the upward shift from compactional toward dilational shear as magma approached the surface, and discuss their importance in controlling the permeability development of magma evolving from overall ductile to increasingly brittle behaviour during ascent and eruption.

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