Estimation of Minimum Principal Stress from an Extended Leak-off Test Onboard the &lt;i&gt;Chikyu&lt;/i&gt; Drilling Vessel and Suggestions for Future Test Procedures

Lin, Wen-Shin; Yamamoto, Keizô; Ito, H.; Masago, Hideki; Kawamura, Y.

doi:10.5194/sd-6-43-2008

Cited by 41 publications

(4 citation statements)

References 2 publications

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“…The basic steps to perform FSTs are described as follows: Conduct a casing integrity test (CIT) before drilling the casing shoe to ensure the integrity of the casing. Drill 10–20 feet below the casing shoe and circulate the mud to condition it. Pull the drill bit back into the casing to prevent the downhole assembly from sticking during the test. Connect the cement unit to the drill pipe and/or annulus and close the rams around the drill pipe. Start pumping mud into the isolated system while recording the pressure and the volume of mud that is pumped until the target test pressure is reached. …”

Section: Hoop Stresses In the Wellborementioning

confidence: 99%

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Overview of Leak-Off Test and Formation Integrity Test: Test Interpretation and Pitfalls

Al Ramadan

2024

ACS Omega

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Formation strength tests, such as formation integrity test (FIT), leak-off test (LOT), and extended leak-off test (XLOT), are crucial for maintaining wellbore stability. Wellbore stability issues are the main reason for nonproductive time (NPT) especially in the drilling operation. Therefore, it is important to understand the stresses around the wellbore to better interpret the formation strength tests. These tests are carried out to (i) test the casing shoe strength, (ii) estimate the minimum horizontal stress, (iii) derive the maximum horizontal stress, and (iv) estimate the fracture pressure gradient. By understanding the stresses around the wellbore and the results of the formation strength tests, engineers can make informed decisions about casing design, cementing practices, and drilling operations. This can help to prevent wellbore instability and NPT, which can save time and money. This study comprehensively reviewed, examined, and analyzed all the available tests currently employed in the field. The goal is to provide an in-depth understanding of each technique and to identify any potential limitations. A deep literature review was conducted to identify all the available tests. Each test was examined in detail to understand its purpose, methodology, and limitations. Then, the results of the tests were analyzed to identify any trends or patterns. The findings of the study were summarized and presented in this paper. Several factors were considered in the analysis of the tests such as formation permeability, formation strength, stresses around the wellbore, fluid properties, and mud type. The results of the study can be used to improve the understanding of formation strength tests and to develop more accurate and reliable methods for interpreting the results. The study considers several factors in the analysis of the tests, such as formation permeability, formation strength, stresses around the wellbore, fluid properties, and mud type. This is different from previous studies, which have often focused on a single factor or a small number of factors.

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Section: Hoop Stresses In the Wellborementioning

confidence: 99%

“…The basic steps to perform FSTs are described as follows: 7 Conduct a casing integrity test (CIT) before drilling the casing shoe to ensure the integrity of the casing. Drill 10–20 feet below the casing shoe and circulate the mud to condition it.…”

Section: Hoop Stresses In the Wellborementioning

confidence: 99%

Overview of Leak-Off Test and Formation Integrity Test: Test Interpretation and Pitfalls

Al Ramadan

2024

ACS Omega

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“…Determining in situ stress at depth is required in different programs, especially in hydraulic fracturing and drilling operations. In this regard, LOT and XLOT data can be used for estimating the magnitude of the in situ minimum principal stress at depth [51][52][53]. Addis et al, for the first time, compared the LOT and XLOT results in the North West Shelf of Australia and the Norwegian North Sea and concluded that the XLOT results were more consistent than LOTs and despite consuming longer time, obtained much preferable data than LOT and recommended XLOT tests where stress data are needed [21].…”

Section: Lot/xlot Application In In-situ Stress Estimation and Geomec...mentioning

confidence: 99%

Review of the Leak-off Tests with a Focus on Automation and Digitalization

Bakhshi

Elahifar

Shahrabadi³

et al. 2022

Int. J. Petrol. Technol.

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The drilling and research communities are leading the way toward more digitally-controlled operations to ensure that the drilling process takes place as safely and gently as possible with the lowest possible carbon footprint. Today’s cutting-edge operations are run on large high-performance drilling installations where operations are largely run remotely from the driller’s operating station. Digitalization of the drilling process is the goal for performing drilling operations remotely from onshore. Leak-off test (LOT) or extended leak-off test (XLOT) plays a critical role in the petroleum industry. Therefore, recognizing all affecting parameters on LOT/XLOT and Formation integrity test (FIT) performance is vital. Because, in some cases, it is not possible to fully understand what happened during the test, having a deep insight into the LOT procedure is very important. One of the current study's main objectives is to thoroughly explain all stages of these tests and assemble all the significant parameters. Thus, many scientific papers on these tests were deeply reviewed and were classified into four main groups focusing on the application of LOT/XLOT (i) in stress estimation and geomechanical studies, (ii) concerning hydraulic fracturing, (iii) concerning wellbore stability, and (iv) numerical modeling, and then, the corresponding discussions were conducted. It was found that in-situ stress estimation is the most common application of the leak-off test. Moreover, considering the importance of LOT and the desire to digitize operations in the oil and gas industry, it was found that the automatic LOT/XLOT is a fully required approach. The primary purpose of this study, which is hence considered its main contribution, is to prepare a LOT flowchart that would set off the further code development tasks of the field. The fundamental code of the present study was written and checked using a real dataset in a Python environment. The results were satisfying and indicated a successful start, which lays a foundation for future automated LOT/XLOT tests.

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“…The vertical stress S v is typically computed by integrating over the density log from the surface to a predetermined depth. The minimum horizontal stress, S hmin , is estimated from pressure monitoring during hydraulic fracturing tests (if they propagate perpendicular to S hmin ) performed in isolated intervals (Fairhurst, 2003;Lin et al, 2008;Ljunggren et al, 2003;Schmitt et al, 2012). However, estimation of the maximum principal stress S hmax is somewhat challenging and associated with a significant amount of uncertainty.…”

Section: In Situ Stress Characterizationmentioning

confidence: 99%

Fracture Network Characterization Using Stress‐Based Tomography

et al. 2018

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Information on structural features of a fracture network at early stages of Enhanced Geothermal System development is mostly restricted to borehole images and, if available, outcrop data. However, using this information to image discontinuities in deep reservoirs is difficult. Wellbore failure data provides only some information on components of the in situ stress state and its heterogeneity. Our working hypothesis is that slip on natural fractures primarily controls these stress heterogeneities. Based on this, we introduce stress‐based tomography in a Bayesian framework to characterize the fracture network and its heterogeneity in potential Enhanced Geothermal System reservoirs. In this procedure, first a random initial discrete fracture network (DFN) realization is generated based on prior information about the network. The observations needed to calibrate the DFN are based on local variations of the orientation and magnitude of at least one principal stress component along boreholes. A Markov Chain Monte Carlo sequence is employed to update the DFN iteratively by a fracture translation within the domain. The Markov sequence compares the simulated stress profile with the observed stress profiles in the borehole, evaluates each iteration with Metropolis‐Hastings acceptance criteria, and stores acceptable DFN realizations in an ensemble. Finally, this obtained ensemble is used to visualize the potential occurrence of fractures in a probability map, indicating possible fracture locations and lengths. We test this methodology to reconstruct simple synthetic and more complex outcrop‐based fracture networks and successfully image the significant fractures in the domain.

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Estimation of Minimum Principal Stress from an Extended Leak-off Test Onboard the <i>Chikyu</i> Drilling Vessel and Suggestions for Future Test Procedures

Abstract: No abstract available. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.6.06.2008" target="_blank">10.2204/iodp.sd.6.06.2008</a>

Cited by 41 publications

References 2 publications

Overview of Leak-Off Test and Formation Integrity Test: Test Interpretation and Pitfalls

Overview of Leak-Off Test and Formation Integrity Test: Test Interpretation and Pitfalls

Review of the Leak-off Tests with a Focus on Automation and Digitalization

Fracture Network Characterization Using Stress‐Based Tomography

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