Maximum Horizontal Stress and Wellbore Stability While Drilling: Modeling and Case Study

2010 ◽  
Author(s):  
Shuling Li ◽  
Cary C. Purdy
Keyword(s):  
Horizontal Stress ◽  
Wellbore Stability ◽  
Maximum Horizontal Stress

Unexpected HTI velocity anisotropy: a wide-azimuth, low fold, 3D seismic processing case study

2014 ◽  
Vol 54 (2) ◽  
pp. 1
Author(s):  
Randall Taylor ◽  
Simon Cordery ◽  
Sebastian Nixon ◽  
Karel Driml
Keyword(s):  
Survey Design ◽  
Local Stress ◽  
Horizontal Stress ◽  
3D Design ◽  
Seismic Processing ◽  
Velocity Anisotropy ◽  
Before And After ◽  
Key Steps ◽  
Maximum Horizontal Stress

This case-study demonstrates seismic processing in the presence of Horizontal Transverse Isotropic (HTI) velocity anisotropy encountered in a low-fold land 3D survey in New Zealand. The HTI velocity anisotropy was unexpected, being suspected only after the initial poor stack response compared to vintage 2D sections in the area, and the sparse 3D design made it difficult to identify. The paper shows how anisotropy was singled out from other possible causes, such as geometry errors. We discuss the key steps of the processing flow incorporated to deal with the HTI anisotropy to attain a high quality final processed volume. In particular we show data examples after the application of azimuthally dependant NMO velocities, along with pre-stack HTI migration. Examples are shown which demonstrate the preservation of the HTI anisotropy before and after 5D trace interpolation. Maps and vertical profiles of 3D attributes are used to demonstrate the magnitude and direction of the HTI velocity field, which varies 5% to 10% between the fast and slow horizontal directions. These observations coincide with the local stress state deduced from borehole break-out studies. We conclude that the fast velocity direction corresponds to the present maximum horizontal stress direction. Finally the paper summarises the implications for processing wide azimuth 3D data in this area and suggests improvements for future 3D survey design. This paper was originally published in the Proceedings of the 23rd International Geophysical Conference and Exhibition, which was held from 11–14 August 2013 in Melbourne, Australia.

Design of Horizontal Wellbore in Dadas Shales of Turkey by Considering Wellbore Stability and Reservoir Geomechanics

2021 ◽  
Author(s):  
Sukru Merey ◽  
Can Polat ◽  
Tuna Eren
Keyword(s):  
Hydraulic Fracturing ◽  
Horizontal Well ◽  
Oil And Gas ◽  
Horizontal Wells ◽  
Horizontal Stress ◽  
Wellbore Stability ◽  
Horizontal Drilling ◽  
Horizontal Wellbore ◽  
Reservoir Geomechanics ◽  
Maximum Horizontal Stress

Abstract Currently, many horizontal wells are being drilled in Dadas shales of Turkey. Dadas shales have both oil (mostly) and gas potentials. Thus, hydraulic fracturing operations are being held to mobilize hydrocarbons. Up to 1000 m length horizontal wells are drilled for this purpose. However, there is not any study analyzing wellbore stability and reservoir geomechanics in the conditions of Dadas shales. In this study, the directions of horizontal wells, wellbore stability and reservoir geomechanics of Dadas shales were designed by using well log data. In this study, the python code developed by using Kirsch equations was developed. With this python code, it is possible to estimate unconfined compressive strength in along wellbore at different deviations. By analyzing caliper log, density and porosity logs of Dadas shales, vertical stress of Dadas shales was estimated and stress polygon for these shale was prepared in this study. Then, optimum direction of horizontal well was suggested to avoid any wellbore stability problems. According to the results of this study, high stresses are seen in horizontal directions. In this study, it was found that the maximum horizontal stress in almost the direction of North-South. The results of this study revealed that direction of maximum horizontal stress and horizontal well direction fluid affect the wellbore stability significantly. Thus, in this study, better horizontal well design was made for Dadas shales. Currently, Dadas shales are popular in Turkey because of its oil and gas potential so horizontal drilling and hydraulic fracturing operations are being held. However, in literature, there is no study about horizontal wellbore designs for Dadas shales. This study will be novel and provide information about the horizontal drilling design of Dadas shales.

Stress Magnitudes from Logs: Effects of Tectonic Strains and Temperature

1999 ◽  
Vol 2 (01) ◽  
pp. 62-68 ◽  
Author(s):  
T.L. Blanton ◽  
J.E. Olson
Keyword(s):  
Horizontal Stress ◽  
Tectonic Stress ◽  
In Situ Stress ◽  
Wellbore Stability ◽  
Stress Tests ◽  
Industry Standard ◽  
Stress Profiles ◽  
Fracture Height ◽  
Minimum Horizontal Stress ◽  
Maximum Horizontal Stress

Summary An improved method of calibrating in-situ stress logs was validated with data from two wells. Horizontal stress profiles are useful for hydraulic fracture design, wellbore stability analysis, and sand production prediction. The industry-standard method of estimating stresses from logs is based on overburden, Poisson's ratio, and pore pressure effects and gives an estimate of minimum horizontal stress. The model proposed here adds effects of temperature and tectonics and outputs of minimum and maximum horizontal stress magnitudes, which are particularly important to the successful completion of horizontal and deviated wells. This method was validated using data collected from a GRI research well and a Mobil well. Seven microfrac stress tests in GRI's Canyon Gas Sands Well of Sutton County, Texas, provided a means of comparing the predictive capability of different methods. First, one of the seven stress tests was selected as a calibration standard for the stress log. Then the results obtained from the two calibration methods were compared to stress magnitudes from the other six stress tests. This process was repeated using each of the seven stress tests as a calibration standard and comparing predictions to the other six. In every case, the method incorporating tectonic strain and thermal effects produced significantly more accurate values. The Mobil well is located in the Lost Hills Field in California, and pre-frac treatment breakdown tests were used to calibrate a log-derived stress profile. All of the data were used simultaneously to get a best fit for the log-derived stress. The log and its fracture height growth implications compared favorably with available fracture diagnostic data, and maximum horizontal stress values were consistent with published values for a similar, nearby reservoir. Introduction Advances in well completion technology have made accurate profiles of horizontal stresses more important to successful field development. Data on in-situ stress have always been important to hydraulic fracture design, wellbore stability analysis, and sand production prediction. More recent work has shown that accurate stress profiles can be used to optimize fracturing of horizontal wells and designing multizone fracture treatments. In fracturing horizontal wells, stress profiles can be used to select zones for the horizontal section that optimize fracture height.1 For multizone fracturing, the success of advanced limited-entry techniques depends on having accurate profiles of horizontal stresses.2 Theory Conventional Method. The industry-standard method3-9 of calculating stresses from logs is based on the following equation: σ h m i n = μ 1 − μ ( σ v e r t − α p p ) + α p p . ( 1 ) The shmin formula is obtained by solving linear poroelasticity equations for horizontal stress with vertical stress set equal to the overburden and horizontal strains set to zero. The only deformation allowed is uniaxial strain in the vertical direction. Overburden stress, svert, is determined from an integrated density log. Poisson's ratio, m, is calculated from compressional and shear wave velocities given by an acoustic log. When independent measures of horizontal stress magnitudes are available from microfracs or extended leak-off tests, there is often a discrepancy between the log-derived and measured values, leading to the conclusion that the uniaxial strain assumption inherent to Eq. (1) is inadequate. In order to improve the estimated stress values, an adjustment (calibration) is made by adding an additional stress term to Eq. (1), thereby shifting the profile to match the measured values.4-8 For the purposes of this article, a constant shift with depth is used, stect which in some cases has been referred to as tectonic stress.5 Eq. (1) then becomes what we term here the conventional method stress equation: σ h m i n = μ 1 − μ ( σ v e r t − α p p ) + α p p + σ t e c t , ( 2 ) where σ t e c t = { σ h m i n ′ − μ ′ 1 − μ ′ ( σ v e r t ′ − α p ′ p ′ ) − α p ′ p ′ } . ( 3 ) The primes indicate parameter values at the calibration depth, z¢ where a measure of the minimum horizontal stress, σhmin′, is available. When measured values are available for several zones, slightly different calibration techniques are used, such as multiplying the log-based stress by a constant factor and adding a "tectonic" gradient.6 These calibrations have physical implications. When horizontal stress is applied as in Eq. (2), the zero lateral strain boundary conditions used to derive Eq. (1) are no longer appropriate. If we assume the strain in the direction orthogonal to the applied tectonic stress is zero (plane strain), the normal strain in the direction of the applied calibration stress, [epsiv] (z), can be written as ε ( z ) = E ( z ) 1 − μ ( z ) 2 σ t e c t , ( 4 ) where E and m are functions of depth. Given that typical geologic sequences are layered in elastic moduli, Eq. (4) implies that a constant tectonic stress calibration [exemplified in Eqs. (2) and (3)] results in horizontal strains that may be discontinuous across layer boundaries, which is a nonphysical consequence of the conventional log-derived stress calibration approach.

Formation evaluation case study: Glyde unconventional Middle Proterozoic play in the McArthur Basin, northern Australia

2015 ◽  
Vol 55 (2) ◽  
pp. 429
Author(s):  
Marcel Croon ◽  
Joshua Bluett ◽  
Luke Titus ◽  
Raymond Johnson
Keyword(s):  
Horizontal Stress ◽  
Gas Production ◽  
Black Shales ◽  
Gas Source ◽  
Pilot Programs ◽  
Log Interpretation ◽  
Maximum Horizontal Stress ◽  
Hydrothermal Dolomite

The Glyde–1 and Glyde Sidetrack–1 wells were drilled by Armour Energy in the Glyde Sub-basin of the McArthur Basin, NT, Australia in August 2012. This program was to evaluate the unconventional hydrocarbon potential of the Barney Creek Shale source rock and the conventional potential of the Coxco Dolomite of the McArthur Group. The Glyde wells discovered gas in both formations. Transtensional faults in this region allowed to form a series of fault-bounded depocentres. The target gas source of the Glyde discovery is located in 1640 Ma organic-rich black shales of the Barney Creek Formation. Weatherford was contracted to acquire both vertical and lateral advanced log suites and perform subsequent log interpretation to constrain the in situ minimum and maximum horizontal stress regimes to assist with maximising gas production from future lateral placement pilot programs in the Coxco Hydrothermal Dolomite (HTD) Play. Two stratigraphic and structural domains were defined by the observed features in the image log data; a dolostone dominated, fractured strata below an erosional surface. Above this stratigraphic timeline is a monotonous package of laminated, lower-energy Barney Creek Formation sediments. Observed changes in azimuths and dips of the measured beddings suggest a phase of compression after deposition of the Barney Creek Formation, resulting in gentle folding of the formations. The porous gas-charged HTD play is drilled in top of the anticline, which is further characterised by a significant number of conductive fractures, likely indicative of open fractures.

scholarly journals Breakouts derived from image logs aid the estimation of maximum horizontal stress: A case study from Perth Basin, Western Australia

2020 ◽  
Vol 5 (1) ◽  
pp. 8-24
Author(s):  
Mohammadali Faraji ◽  
Alireza Rezagholilou ◽  
Mandana Ghanavati ◽  
Ali Kadkhodaie ◽  
David A. Wood
Keyword(s):  
Western Australia ◽  
Horizontal Stress ◽  
Maximum Horizontal Stress
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