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Chemical effect on wellbore instability of Nahr Umr Shale.

Yu B, Yan C, Nie Z - ScientificWorldJournal (2013)

Bottom Line: Wellbore instability is one of the major problems that hamper the drilling speed in Halfaya Oilfield.Complex accidents such as wellbore collapse and sticking emerged frequently in this formation.Finally, we put forward engineering countermeasures for safety drilling in Halfaya Oilfield and point out that increasing the ionic concentration and improving the sealing capacity of the drilling fluid are the way to keep the wellbore stable.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing 102249, China.

ABSTRACT
Wellbore instability is one of the major problems that hamper the drilling speed in Halfaya Oilfield. Comprehensive analysis of geological and engineering data indicates that Halfaya Oilfield features fractured shale in the Nahr Umr Formation. Complex accidents such as wellbore collapse and sticking emerged frequently in this formation. Tests and theoretical analysis revealed that wellbore instability in the Halfaya Oilfield was influenced by chemical effect of fractured shale and the formation water with high ionic concentration. The influence of three types of drilling fluids on the rock mechanical properties of Nahr Umr Shale is tested, and time-dependent collapse pressure is calculated. Finally, we put forward engineering countermeasures for safety drilling in Halfaya Oilfield and point out that increasing the ionic concentration and improving the sealing capacity of the drilling fluid are the way to keep the wellbore stable.

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Related in: MedlinePlus

Comparison of the shale strength decrease after immersing.
© Copyright Policy - open-access
Related In: Results  -  Collection


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fig4: Comparison of the shale strength decrease after immersing.

Mentions: In order to analyze the influence of the drilling fluid on the wellbore stability of the Nahr Umr Shale, experimental studies were carried on the influence of drilling fluid on the rock mechanical property. We tested the shale strength of Nahr Umr Shale after immersing it in different kinds of drilling fluids. Table 6 shows the uniaxial compressive strength (UCS, MPa) results from the test. Figure 4 illustrates the comparison of the strength variation rule versus the time after immersing in different kinds of drilling fluid.


Chemical effect on wellbore instability of Nahr Umr Shale.

Yu B, Yan C, Nie Z - ScientificWorldJournal (2013)

Comparison of the shale strength decrease after immersing.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3824561&req=5

fig4: Comparison of the shale strength decrease after immersing.
Mentions: In order to analyze the influence of the drilling fluid on the wellbore stability of the Nahr Umr Shale, experimental studies were carried on the influence of drilling fluid on the rock mechanical property. We tested the shale strength of Nahr Umr Shale after immersing it in different kinds of drilling fluids. Table 6 shows the uniaxial compressive strength (UCS, MPa) results from the test. Figure 4 illustrates the comparison of the strength variation rule versus the time after immersing in different kinds of drilling fluid.

Bottom Line: Wellbore instability is one of the major problems that hamper the drilling speed in Halfaya Oilfield.Complex accidents such as wellbore collapse and sticking emerged frequently in this formation.Finally, we put forward engineering countermeasures for safety drilling in Halfaya Oilfield and point out that increasing the ionic concentration and improving the sealing capacity of the drilling fluid are the way to keep the wellbore stable.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing 102249, China.

ABSTRACT
Wellbore instability is one of the major problems that hamper the drilling speed in Halfaya Oilfield. Comprehensive analysis of geological and engineering data indicates that Halfaya Oilfield features fractured shale in the Nahr Umr Formation. Complex accidents such as wellbore collapse and sticking emerged frequently in this formation. Tests and theoretical analysis revealed that wellbore instability in the Halfaya Oilfield was influenced by chemical effect of fractured shale and the formation water with high ionic concentration. The influence of three types of drilling fluids on the rock mechanical properties of Nahr Umr Shale is tested, and time-dependent collapse pressure is calculated. Finally, we put forward engineering countermeasures for safety drilling in Halfaya Oilfield and point out that increasing the ionic concentration and improving the sealing capacity of the drilling fluid are the way to keep the wellbore stable.

Show MeSH
Related in: MedlinePlus