Optimising Remote Unconventional Gas Exploration

Rylance, Martin

doi:10.2118/163987-ms

Cited by 8 publications

(2 citation statements)

References 29 publications

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“…This is larger than the typical range used for the matrix of shale (%10 to 100 nd; Wang et al 2011;Sakhaee-Pour and Bryant 2012). If we take a smaller value for the matrix permeability, the ratio of the flow rates becomes even larger (see Eq.…”

Section: Interactions Between Adjacent Cells In a Fractured Reservoirmentioning

confidence: 91%

“…The thickness of the adsorbed layer lessens as the reservoir pressure decreases, and this leads to an increase of the void space. To account for this effect, researchers have modeled the increase of the void space and have proposed new models for porosity (Hartman et al 2011;Ambrose et al 2012) and permeability (Sakhaee-Pour and Bryant 2012;Sinha et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Effective Flow Properties for Cells Containing Fractures of Arbitrary Geometry

Sakhaee‐Pour

Wheeler

2016

SPE Journal

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Hydrocarbon production from unconventional resources such as shale usually entails stimulation by hydraulic fracturing, which results in nonplanar (curved) fractures. However, most reservoir models assume that the induced fractures are planar for the sake of simplicity. Considering the growing interest of the petroleum industry in better understanding production from these resources, we develop a fracture-cell model to capture the effects of fracture nonplanarity on transport properties.To build a realistic reservoir model for a fractured formation, we must account for three types of interactions: matrix-matrix (M-M), matrix-fracture (M-F), and fracture-fracture (F-F). The transport properties of the M-M interaction are based on laboratory measurements. In this study, we analytically determine the transport properties of the two other types of interactions (M-F and F-F). For this purpose, we account for the aperture size and spatial location of the fracture. As a result, we provide effective porosity and effective anisotropic permeabilities for a reservoir cell that contains a fracture inside it. The reservoir cell with transport properties that are modified is a fracture cell.We implement the fracture-cell model in a reservoir simulator and perform analyses for a single fracture and for multiple intersecting fractures; these fractures are nonplanar. The analyses include both single-and multiphase flow models and show that the hydrocarbon pressure inside the reservoir is strongly dependent on the fracture geometry when the matrix permeability is smaller than 1 md. Thus, it is crucial to model the fracture geometry more accurately in unconventional reservoirs with ultralow permeabilities such as shale.One can easily implement the developed fracture-cell model in reservoir simulators, and there is no local refinement around the fracture. The main advantage of the proposed model is its simplicity, conjoined with its ability to capture the nonplanarity of the fracture. The developed model has major applications for understanding production from formations that are heavily fractured.

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Section: Interactions Between Adjacent Cells In a Fractured Reservoirmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Effective Flow Properties for Cells Containing Fractures of Arbitrary Geometry

Sakhaee‐Pour

Wheeler

2016

SPE Journal

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The US Shale Gas "Revolution": A Review of the Production Performance and Geology to Establish Potential Economic Benchmarks for Australia

Starkey¹,

Katelis²,

McGhee³

2014

SPE Asia Pacific Oil &Amp; Gas Conference and Exhibition

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Shale plays have created the current natural gas boom in the United States (US) and according to the national Energy Information Administration (EIA, 2013)49 produced 47% of total daily production by the end of 2013 (approximately 31.8 Bscf/d). Extensive production data from thousands of wells are now available for analysis to provide potential benchmark information for the Australian shale gas industry, which is still in its infancy. This paper focusses on analysis of publicly available US production data from horizontal wells in five depositional basins reported for the Barnett, Eagle Ford, Fayetteville, and Haynesville shale plays. Type-wells are evaluated which allow estimation of a range of representative initial gas production rate and technical Estimated Ultimate Recovery (EUR) characteristics. The analysis also results in generic recommendations for the minimum sample size and duration required for statistically significant well appraisal programs in shale plays. Such activity phases' primary objective should be to efficiently obtain reasonably reliable type-well performance indicators. The US shale plays' experiences to date provide insight concerning this aspect. Variability in geological factors including, but not limited to: stress regime, total organic content, thermal maturity, porosity, brittleness, natural fractures, and reservoir pressure can result in production performance that differs substantially both within and between shale plays. Also affecting performance is how the wells are completed. The geology of shale formations is discussed along with recent Australian operational activity, geomechanical considerations, and example economics. Analyses of the US data provide potential technical and economic benchmarks for preliminary comparisons to be made with Australian information, and may help to demonstrate the economic resilience required for exploitation of prospective shale gas resources. However, it must be recognised that the likely performance characteristics of the prospective Australian shale plays' type-wells are not currently well understood due to lack of data. Significant exploration and appraisal activity is needed to augment the extremely limited shale gas well performance data available in Australia to date.

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After Closure Analysis as an Appraisal Approach

Usmanova¹,

Smith²,

Rylance³

2016

All Days

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Conventional appraisal consists of drilling, completing and producing a number of wells, with each of these wells being required to establish a production history and sufficient offtake to demonstrate a substantial connected volume. The technique of After Closure Analysis (ACA) offers a complementary or alternative approach to conventional testing, to establish important formation characteristics such as transmissibility (kh//), pore pressure and connected volumes. The principal advantage being that the approach is substantially less time consuming and costly than conventional approaches, particularly in the case of tight formations where substantial enhancement/stimulation may be required in order to establish any sustainable production in the first place. ACA consists of injecting a fixed volume of fluid above fracturing pressure and at relatively low rates, and then subsequently monitoring the pressure decline response. This approach potentially allows for the calculation of a highly accurate assessment of the transmissibility and combined with formation fluid data the effective kh to this formation fluid. While this technique has been utilised for some time, the application of ACA has been fairly limited in established fields as a reasonably accurate reservoir pressure is required for a meaningful result and therefore depleted environments can present issues. However, in the case of Exploration and Appraisal, formation pressure is typically undisturbed and therefore this approach is well suited and in fact ideal in this case. The paper will present a series of case histories in a variety of hydrocarbon bearing environments and work the details from the initial concept through demonstration of the results. Additionally, a suite of complimentary pressure transient analyses using conventional approaches will demonstrate the validity of the results. The case histories will clearly demonstrate the relative value that can be achieved by this technique, with direct comparison to conventional approaches. The value of the approach in tighter rock environments will be directly demonstrated. Additionally, a suite of type-curves and selection graphs will be presented that can be used to determine pumping-stage design and decline period requirements. Finally, a suite of lessons learned and operational considerations will be provided in order to maximise the overall efficiency of the approach. Conventional appraisal approaches require extensive flow-periods and substantial fluid offtake to determine the immediate region of influence/connectivity. The use of ACA offers a supportive and complimentary technique that in combination with a reduced set of conventional test wells offers to augment the datasets available for interpretation at just a fraction of the cost/time of conventional methods. In remote and hard-to-recover areas where such conventional tests can prove inefficient, this technique offers an alternative and complementary means of appraising formations.

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Optimising Remote Unconventional Gas Exploration

Cited by 8 publications

References 29 publications

Effective Flow Properties for Cells Containing Fractures of Arbitrary Geometry

Effective Flow Properties for Cells Containing Fractures of Arbitrary Geometry

The US Shale Gas "Revolution": A Review of the Production Performance and Geology to Establish Potential Economic Benchmarks for Australia

After Closure Analysis as an Appraisal Approach

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