Brittleness of gas shale reservoirs: A case study from the north Perth basin, Australia

Shale reservoirs have gained the attention of many in recent years due to their potential as a major gas resource. Production from this kind of formation, however, requires an accurate estimation of brittleness and employments of hydraulic fracturing. There have been many studies as to how brittleness can be estimated, but few research works were carried out so far indicating how brittleness indices vary in gas shale formations. The aim of this paper is to evaluate the variation of brittleness in one of the gas shale reservoirs located in the north Perth Basin of Australia. The results obtained indicated that the lower part of the Carynginia shale should be selected for a hydraulic fracturing job due to a high brittleness index, although a careful analysis of Total Organic Content (TOC) might be required before initiating any plans. The mineralogical report and interpretations revealed that the space created by cross-plotting the elastic parameters is able to identify dominant minerals contributing into brittleness. Performing a series of true triaxial tests, which are capable of simulating the real field condition by applying three independent principal stresses, implied that as the stress anisotropy increases, a transition takes place from brittle towards the ductile behaviours. However, when this anisotropy becomes significant, samples regain their strength. This study, therefore, recommends more studies to get a practical conclusion on brittleness under true triaxial conditions

Assessing the free surface tracking approach to simulate extrudate swell

The extrudate swell, the geometrical modifications that take place when the flowing material leaves the confined flow inside a channel and moves freely without the restrictions promoted by the walls, is a relevant phenomenon in several polymer processing techniques. For instance, in profile extrusion, the extrudate cross-section suffers a number of distortions motivated by swell, which are very difficult to anticipate, especially for complex geometries. As happens in many industrial processes, numerical modelling might provide useful information to support design tasks, enabling to identify the best strategy to compensate the changes promoted by the extrudate swell. There are different ways to model free-surface flows, which can be grouped in Interface Tracking (IT) and Interface Capturing (IC) approaches. When dealing with steady state processes, which is the case of profile extrusion, IT is usually the best alternative, since it does not present the problems related to interface diffusion inherent to the IC approaches. OpenFOAM comprises a solver to simulate free-surface flows following an IT approach, which was proposed by Tukovic & Jasak (2008) and Tukovic et al., (2012). This work aims to assess the capability of that solver to simulate the extrudate swell process in profile extrusion, by using the interfaceTrackingFvMesh and interTrackMeshMotion libraries available in OpenFOAM-v1912 to track the free surface movement with a dynamic mesh motion. For this purpose, the data provided by Mitsoulis et al., (2012) on simulation of the extrudate swell of a Newtonian fluid at different Reynolds number flows is considered as the reference for validation.The authors would like to acknowledge the funding by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects UIDB/05256/2020 and UIDP/05256/2020, TSSiPRO - Technologies for Sustainable and Smart Innovative Products (NORTE-01-0145-FEDER-000015) and FAMEST - Footwear, Advanced Materials, Equipment’s and Software Technologies (POCI-01-0247-FEDER-024529). The authors also acknowledge the support of the computational clusters Search-ON2 (NORTE-07-0162-FEDER-000086) and Minho Advanced Computing Center (MACC)

A nano-particle based approach to improve filtration control of water based muds under high pressure high temperature conditions

There have been many attempts to improve the filtration control of water based muds under High Pressure High Temperature (HPHT) condition using a cost effective approach. Nano particles are perhaps the best option considering their successful applications reported in many studies. However, they are often expensive and pose unfavourably changes on the rheology of the muds. In this paper, an attempt was made to show the application of Nano Glass Flakes (NGFs) as a cheap but effective nano particle to control the filtration of water based muds under HPHT conditions. Performing a series of rheology, filtration and conductivity tests on the mud samples with unmodified NGFs revealed that this nano particle increases the mud rheology, yield point and gel strength of the mud with a slight impact on the filtration loss. However, by modifying the surface charges of NGFs with a cationic surfactant, filtration loss was significantly reduced without any severe impacts on the mud rheology. Considering the conductivity of the mud which increases by adding the modified NGF, this nano particle might be a good choice to improve the overall performance of water based muds under HPHT conditions

AP-4-mediated axonal transport controls endocannabinoid production in neurons

Davies et al. identify a putative mechanism underlying the childhood neurological disorder AP-4 deficiency syndrome. In the absence of AP-4, an enzyme that makes 2-AG is not transported to the axon, leading to axonal growth defects, which can be rescued by inhibition of 2-AG breakdown. The adaptor protein complex AP-4 mediates anterograde axonal transport and is essential for axon health. AP-4-deficient patients suffer from a severe neurodevelopmental and neurodegenerative disorder. Here we identify DAGLB (diacylglycerol lipase-beta), a key enzyme for generation of the endocannabinoid 2-AG (2-arachidonoylglycerol), as a cargo of AP-4 vesicles. During normal development, DAGLB is targeted to the axon, where 2-AG signalling drives axonal growth. We show that DAGLB accumulates at the trans-Golgi network of AP-4-deficient cells, that axonal DAGLB levels are reduced in neurons from a patient with AP-4 deficiency, and that 2-AG levels are reduced in the brains of AP-4 knockout mice. Importantly, we demonstrate that neurite growth defects of AP-4-deficient neurons are rescued by inhibition of MGLL (monoacylglycerol lipase), the enzyme responsible for 2-AG hydrolysis. Our study supports a new model for AP-4 deficiency syndrome in which axon growth defects arise through spatial dysregulation of endocannabinoid signalling.Special thanks to the MPIB Imaging Facility for outstanding technical support, in particular to Giovanni Cardone for his advice and assistance with the implementation of image analysis pipelines, as well as feedback on the manuscript, and to Martin Spitaler for his expert technical advice for imaging experiments

A Geologic Study to Determine the Potential to Create an Appalachian Storage Hub for Natural Gas Liquids

The Marcellus and Utica shale plays continue to lead the way in an ever-expanding shale revolution with average daily production, growing from about 3 billion cubic feet (BCF) in 2010 to more than 24 BCF today. Forecasts suggest that this could grow to as much as 40 BCF in the next 5 years. Fortunately, sweet spots in the Utica in eastern Ohio and in the Marcellus in northern West Virginia and southwestern Pennsylvania are areas of wet gas production, downdip from oil production and updip from dry gas. Production in these regions represents about 40 percent of the total from the Marcellus and Utica shales and is expected to represent a disproportionate share of future production growth. Because of the amount of natural gas liquids (NGLs) contained in this production, development of these shale plays has the potential to have a large impact on the petrochemical industry

High-throughput imaging of ATG9A distribution as a diagnostic functional assay for adaptor protein complex 4-associated hereditary spastic paraplegia

Adaptor protein complex 4-associated hereditary spastic paraplegia is caused by biallelic loss-of-function variants in AP4B1, AP4M1, AP4E1 or AP4S1, which constitute the four subunits of this obligate complex. While the diagnosis of adaptor protein complex 4-associated hereditary spastic paraplegia relies on molecular testing, the interpretation of novel missense variants remains challenging. Here, we address this diagnostic gap by using patient-derived fibroblasts to establish a functional assay that measures the subcellular localization of ATG9A, a transmembrane protein that is sorted by adaptor protein complex 4. Using automated high-throughput microscopy, we determine the ratio of the ATG9A fluorescence in the trans-Golgi-network versus cytoplasm and ascertain that this metric meets standards for screening assays (Z'-factor robust >0.3, strictly standardized mean difference >3). The `ATG9A ratio' is increased in fibroblasts of 18 well-characterized adaptor protein complex 4-associated hereditary spastic paraplegia patients [mean: 1.54 +/- 0.13 versus 1.21 +/- 0.05 (standard deviation) in controls] and receiver-operating characteristic analysis demonstrates robust diagnostic power (area under the curve: 0.85, 95% confidence interval: 0.849-0.852). Using fibroblasts from two individuals with atypical clinical features and novel biallelic missense variants of unknown significance in AP4B1, we show that our assay can reliably detect adaptor protein complex 4 function. Our findings establish the 'ATG9A ratio' as a diagnostic marker of adaptor protein complex 4-associated hereditary spastic paraplegia

High-throughput imaging of ATG9A distribution as a diagnostic functional assay for adaptor protein complex 4-associated hereditary spastic paraplegia

Adaptor protein complex 4-associated hereditary spastic paraplegia is caused by biallelic loss-of-function variants in AP4B1, AP4M1, AP4E1 or AP4S1, which constitute the four subunits of this obligate complex. While the diagnosis of adaptor protein complex 4-associated hereditary spastic paraplegia relies on molecular testing, the interpretation of novel missense variants remains challenging. Here, we address this diagnostic gap by using patient-derived fibroblasts to establish a functional assay that measures the subcellular localization of ATG9A, a transmembrane protein that is sorted by adaptor protein complex 4. Using automated high-throughput microscopy, we determine the ratio of the ATG9A fluorescence in the trans-Golgi-network versus cytoplasm and ascertain that this metric meets standards for screening assays (Z'-factor robust >0.3, strictly standardized mean difference >3). The 'ATG9A ratio' is increased in fibroblasts of 18 well-characterized adaptor protein complex 4-associated hereditary spastic paraplegia patients [mean: 1.54 ± 0.13 versus 1.21 ± 0.05 (standard deviation) in controls] and receiver-operating characteristic analysis demonstrates robust diagnostic power (area under the curve: 0.85, 95% confidence interval: 0.849-0.852). Using fibroblasts from two individuals with atypical clinical features and novel biallelic missense variants of unknown significance in AP4B1, we show that our assay can reliably detect adaptor protein complex 4 function. Our findings establish the 'ATG9A ratio' as a diagnostic marker of adaptor protein complex 4-associated hereditary spastic paraplegia