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Total organic carbon evaluation of the Bowland Shale Formation in the Upper Bowland of the Widmerpool Gulf
Get PDFWidmerpool Gulf is one of the basins in the carboniferous Bowland Hodder shale in Central Britain. The area of interest in the Widmerpool Gulf is the Bowland Shale Formation within the Upper Bowland. This paper focuses on evaluating the total organic carbon (TOC) from Rempstone 1 and Old Dalby 1 both penetrating the Bowland Shale Formation using Passey’s delta Log R method. TOC is an essential property needed to have a productive shale gas play - accurate characterisation of TOC is critical in evaluating the potential of shale gas reservoirs because it closely relates to the amount of kerogen and therefore total gas content. Passey’s method involves the use of well logs to obtain the organic richness i.e. TOC. It relies on the response of well logs to organic matter using an overlay of porosity logs and resistivity logs. Which causes a separation i.e. a delta Log R separation. The reasons for the delta Log R separation in an organic rich reservoir/non reservoir rocks is due to the presence of low density, high transit time kerogen and the presence of formation fluid i.e. oil, gas or water. Immature source rocks also observe a separation but only from the porosity log whilst non source rocks observe no separation. Rempstone 1 and Old Dalby 1 well logs were exported on Interactive Petrophysics to analyse the lithology of the intervals before been exported to Microsoft Excel to evaluate the parameters of Passey’s equation to enable TOC determination. TOC estimates for the Upper Bowland Shale section in the Widmerpool Gulf and was found comparable to estimates obtained from British Geological Survey (BGS) RockEval core analysis report. This method proved to be a suitable way of estimating the total organic carbon using simple well logs
Economic appraisal of shale gas reservoirs
No full textNatural gas produced from shale formations has increased rapidly in the past decade altering the oil and gas industry markets remarkably. The use of horizontal drilling and hydraulic fracturing has allowed previously unrecoverable shale gas to be extracted. Shale gas development is more expensive compared to conventional developments and as such, understanding the economic feasibility is of greater importance in successfully developing the resource. Using the estimated ultimate recoverable expressed in terms of P10, P50, and P90 from 2751 horizontal well production data (all starting production from 2008) from the Barnett shale, a discounted cash flow economic model (MS- Excel based) was used to quantify the effect of finding and development costs (F&DC) and gas prices on the economic viability of horizontal wells within four out of five basins (Strawn Basin, Ouachita Folded Belt, Forth-worth Syncline and Bendarch Basin) in the Barnett shale. The investment hurdle in the economic model was a rate return of 20% and a payback period of 5 years or less. This paper helps determine the percentage of wells within basins in the Barnett shale that would be economically viable at various F&DC and gas prices subject to satisfying the prescribed investment hurdle
Corrigendum to “Shale gas production decline trend over time in the Barnett Shale” [J. Petrol. Sci. Eng. 165 (2018) 691-710]
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Shale gas production decline trend over time in the Barnett Shale
Get PDFNatural gas produced from shale formations in the United States over the past decade have altered the oil and gas industry remarkably. The Barnett shale was at the forefront of the shale gas revolution in the United States and was considered to be the highest producing natural gas field in the United States until 2012, yielding the top producer spot to the Marcellus shale. Due to the uncertainty regarding the accurate determination of Estimated Ultimate Recoverable (EUR) in shale gas reservoirs, this paper aims to assess EUR values for the Barnett shale using empirical decline curve methods like the Arp's hyperbolic, Modified Arp's hyperbolic and Doung's method. In addition, we investigated the economic viability of wells over time in the Barnett under various probabilities of success. Throughout this paper, reference is made to two key publications where a similar work was carried out for various shale plays in the United States, including the Barnett shale – though only the Arp's hyperbolic decline was employed. The dataset in this paper consisted of more horizontal wells from covering more counties within the Barnett shale compared to other similar studies. We conclude that either the Arp's hyperbolic or Doung's method can be used to forecast EUR in the Barnett shale as only marginal differences were observed. This is on the basis that production history exceeds 10 months (a maximum of 80 months production history was used). We also obtained reliable and conservative estimates of EUR compared to previous studies
Effect of basalt fibre hybridisation on post-impact mechanical behaviour of hemp fibre reinforced composites
Get PDFA major limitation to the spreading of natural fibre reinforced composites in semi-structural components is their unsatisfactory impact performance. As a potential solution, the production of synthetic/plant fibre hybrid laminates has been explored, trying to obtain materials with sufficient impact properties, while retaining a reduced cost and a substantial environmental gain. This study explores the effects of hybridisation of basalt fibre on post-impact behaviour and damage tolerance capability of hemp fibre reinforced composites. All reinforced laminates were impacted in a range of energies (3, 6, and 9 J) and subjected to both quasi-static and cyclic flexural tests with a step loading procedure. The tests have also been monitored by acoustic emission (AE), which has confirmed the existence of severe limitations to the use of natural fibre reinforced composites even when impacted at energies not so close to penetration and the enhanced damage tolerance offered by the hybridisation with basalt fibers
Enhanced history matching process by incorporation of saturation logs as model selection criteria
No full textThis paper proposes a methodology for an alternative history matching process enhanced by the incorporation of a simplified binary interpretation of reservoir saturation logs (RST) as objective function. Incorporating fluids saturation logs during the history matching phase unlocks the possibility to adjust or select models that better represent the near wellbore waterfront movement, which is particularly important for uncertainty mitigation during future well interference assessments in water driven reservoirs. For the purposes of this study, a semi-synthetic open-source reservoir model was used as base case to evaluate the proposed methodology. The reservoir model represents a water driven, highly heterogenous sandstone reservoir from Namorado field in Brazil. To effectively compare the proposed methodology against the conventional methods, a commercial reservoir simulator was used in combination with a state-of-the-art benchmarking workflow based on the Big Loop™ approach. A well-known group of binary metrics were evaluated to be used as the objective function, and the Matthew correlation coefficient (MCC) has been proved to offer the best results when using binary data from water saturation logs. History matching results obtained with the proposed methodology allowed the selection of a more reliable group of reservoir models, especially for cases with high heterogeneity. The methodology also offers additional information and understanding of sweep behaviour behind the well casing at specific production zones, thus revealing full model potential to define new wells and reservoir development opportunities
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Enhancement of mechanical properties of flax-epoxy composite with carbon fibre hybridisation for lightweight applications
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