A log based analysis to estimate mechanical properties and in-situ stresses in a shale gas well in North Perth Basin

This study was carried out to determine the rock mechanical properties relevant for hydrocarbon exploration and production by hydraulic fracturing of organic rich shale formations in Anambra basin. Shale samples and wireline logs were analysed to determine the petrophysical, elastic, strength and in-situ properties necessary for the design of a hydraulic fracturing programme for the exploitation of the shales. The results obtained indicated shale failure in shear and barreling under triaxial test conditions. The average effective porosity of 0.06 and permeability of the order of 10-1 to 101 millidarcies showed the imperative for induced fracturing to assure fluid flow. Average Young’s modulus and Poisson’s ratio of about 2.06 and 0.20 respectively imply that the rocks are favourable for the formation and propagation of fractures during hydraulic fracking. The minimum horizontal stress, which determines the direction of formation and growth of artificially induced hydraulic fractures varies from wellto-well, averaging between 6802.62 to 32790.58 psi. The order of variation of the in-situ stresses is maximum horizontal stress>vertical stress>minimum horizontal stress which implies a reverse fault fracture regime. The study predicts that the sweet spots for the exploration and development of the shale-gas are those sections of the shale formations that exhibit high Young’s modulus, low Poisson’s ratio, and high brittleness. The in-situ stresses required for artificially induced fractures which provide pore space for shale gas accumulation and expulsion are adequate. The shales possess suitable mechanical properties to fracture during hydraulic fracturing. Application of these results will enhance the potentials of the onshore Anambra basin as a reliable component in increasing Nigeria’s gas reserves, for the improvement of the nation’s economy and energy security. Key Words: Hydraulic Fracturing, Organic-rich Shales, Rock Mechanical Properties, Petrophysical Properties, Anambra Basin

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Simulation of hydraulic fracturing in tight formations

The APPEA Journal ◽

10.1071/aj09035 ◽

2010 ◽

Vol 50 (1) ◽

pp. 581 ◽

Cited By ~ 6

Author(s):

Mohammad Sarmadivaleh ◽

Vamegh Rasouli

Keyword(s):

Mechanical Properties ◽

Hydraulic Fracturing ◽

Analytical Models ◽

Particle Flow Code ◽

Gas Formation ◽

In Situ Stresses ◽

Initiation And Propagation ◽

Tight Formations ◽

Tight Gas Formation

Production from tight formations is becoming a main focus around the world and particularly in Australia. Hydraulic fracturing is one of the commonly used approaches to stimulate production from tight reservoirs. A good understanding of mechanical properties of formation and the in-situ stresses is essential for a hydraulic fracturing study. In this work, using the log based approach, the mechanical properties and in-situ stresses were estimated in a tight gas formation. This data is then used as input for 2D numerical simulation of hydraulic fracturing in particle flow code (PFC). The initiation and propagation of an induced fracture was studied by increasing the rock strength to simulate a tight formation response. Thereafter, the model was divided into two zones to investigate the fracture containment capacity to simulate a fracture intersecting an interbed with formation properties being different on the two sides. The formation bond strength was increased on one side of the interbed and fracture extension was monitored. The results of both simulations showed how, by increasing formation strength equivalent to a tighter formation, the fracture extension ability reduces and the interbed containment capacity increases. The results were compared with some of the analytical models and good agreement was observed.

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Mechanical properties and in situ stresses from field data

10.1016/b978-0-12-822195-2.00017-6 ◽

2021 ◽

pp. 429-459

Author(s):

Erling Fjær ◽

Rune Martin Holt ◽

Per Horsrud ◽

Arne Marius Raaen ◽

Rasmus Risnes

Keyword(s):

Mechanical Properties ◽

Field Data ◽

In Situ Stresses

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Calibrating The Mechanical Properties and In-Situ Stresses Using Acoustic Radial Profiles

10.2118/110089-ms ◽

2007 ◽

Cited By ~ 3

Author(s):

Colin Michael Sayers ◽

Saad M. Kisra ◽

Kwasi M. Tagbor ◽

Jose Adachi

Keyword(s):

Mechanical Properties ◽

In Situ Stresses ◽

Radial Profiles

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Some lessons learnt from drilling a shale gas well in Western Australia

The APPEA Journal ◽

10.1071/aj13006 ◽

2014 ◽

Vol 54 (1) ◽

pp. 15

Author(s):

Vamegh Rasouli

Keyword(s):

Mechanical Properties ◽

Shale Gas ◽

Gas Flow ◽

Joint Venture ◽

Gas Well ◽

Eastern Area ◽

Well Design ◽

Surface Location ◽

Coal Measures ◽

Exploration Well

The Arrowsmith–2 well is the first dedicated shale gas well in WA. The well is situated in the central eastern area of Permit EP413, with the surface location being about 30 km north of the township of Eneabba. Norwest, as the operator and on behalf of its joint venture partners, drilled the Arrowsmith–2 exploration well in mid-2011. In 2012 the well was subsequently perforated and fracture stimulated in five discrete stages across four formations: the High Cliff Sand Stone (HCSS); Irwin River Coal Measures (IRCM); Carynginia Formation; and, Kockatea Shale. The fraccing results have shown excellent rates of gas flow for the size of the intervals fracced, and have produced oil and/or condensate to surface from the two intervals flowed back. This paper discusses some drilling operation and design aspects of Arrowsmith–2. A review of the regional geology, basic well design, and well objectives will be given. The importance of geomechanical studies for minimising wellbore-related problems during drilling and after that for hydraulic fracturing operation will be discussed, and the results of the studies undertaken presented. The wireline logging suite run in this well was used to interpret the formations’ mechanical properties. Also, laboratory tests were performed to estimate hydro-mechanical properties of the formations. The lessons from drilling this well will be used for drilling future wells in the area with the objective of saving time and costs.

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Experimental study of shale drillability with different bedding inclinations under varying wellbore pressure conditions

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-021-01140-2 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1751-1759

Author(s):

Shuai Chen ◽

Xiangchao Shi ◽

Heng Bao ◽

Leiyu Gao ◽

Jie Wu

Keyword(s):

Mechanical Properties ◽

Shale Gas ◽

Physical And Mechanical Properties ◽

In Situ Conditions ◽

Wellbore Pressure ◽

Development Engineering ◽

The Impact ◽

The Relationship ◽

Insight Into

AbstractIn the practice of shale gas development engineering, it is important to understand the physical and mechanical properties of shale. The bedding inclinations of shale are known to significantly influence its physical and mechanical properties. This study mainly examined the influence of bedding inclinations on drillability under different wellbore pressures. The bedding inclinations used in this study varied from 0° to 90°, with a gradient of 15°. The wellbore pressure values used varied from 0 to 25 MPa, with a gradient of 5 MPa. The results show that the drillability index of shale increases exponentially with increasing wellbore pressure at different bedding inclinations. The proposed exponential empirical model can describe the relationship between the drillability index and wellbore pressure. When the wellbore pressure is less than 15 MPa, bedding inclinations significantly influence the drillability index, and the drillability index of shale shows a “W”-type variation trend as the bedding inclinations increase in the range of 0° to 90°. The influence of bedding inclinations on drillability decreases gradually with increasing wellbore pressure. When the wellbore pressure increases to 25 MPa, the impact of bedding inclinations on drillability is virtually undetectable. The results of this study can provide reasonably insight into the effect of bedding inclinations on shale deformation under the drill bit, and useful prediction for the drillability index under in situ conditions.

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