Full-Scale Laboratory Study of the Impact of Drilling Fluid Composition and Properties on Penetration Rates in Brazilian Pre-Salt Carbonates

Curry, David; Bland, R.G.; Lourenco, Affonso; Lutes, Paul; Fonseca, Carlos Eduardo; de, Carlos Henrique; Lomba, R.F.T.

doi:10.2118/166325-ms

Cited by 7 publications

(2 citation statements)

References 26 publications

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“…However, it can be inferred from comparison of the visual single point cutter and full scale drilling test results that the fluid properties may well influence the drilling process in salt. There is much debate about the extent to which solids may or may not influence the drilling process, as summarized by Curry et al (2013). Their study indicated that solids content per se did not directly influence penetration rates in the hard carbonates tested.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Borehole Pressure on the Drilling Process in Salt

Curry

Lourenco

Ledgerwood

et al. 2015

SPE/IADC Drilling Conference and Exhibition

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Wells penetrate long intervals of salt to access hydrocarbon reservoirs in many locations. High mud weights are frequently used to stabilise the wellbore while drilling through salt formations. High borehole pressures reduce penetration rates in many sedimentary rocks. This effect is significant and contributes greatly to the low penetration rates and high costs associated with deep drilling. This paper presents the results of an integrated laboratory study of the effect of borehole pressure on the drilling process in salt. The study included full-scale laboratory drilling tests, visual single-point cutter tests and triaxial compression tests. The drilling tests were performed using a Polycrystalline Diamond Compact (PDC) bit and a synthetic-based drilling fluid typical of field practice. The visual single-point cutter tests used a clear drilling fluid, enabling observation and video recording of the salt cutting process at elevated borehole pressures along with simultaneous measurement of the cutting forces.The effect of borehole pressure on drilling salt is seen to be small; increasing borehole pressure does not reduce penetration rates in salt as much as it does in many other sedimentary rocks. In contrast to other sedimentary rocks, salt deforms plastically to relatively large strains in compression without loss of mechanical integrity, even at low confining pressures. In addition, the shear stress to achieve a given strain does not increase greatly with confining pressure. Rock cutting forces in the single-cutter tests increased only moderately as borehole pressure was increased from 300 to 6,000 psi. Full-scale bit penetration rates also decreased by relatively small amounts over the borehole pressure range investigated (1,000 to 6,000 psi). Mechanical specific energy levels showed corresponding small increases. These levels, however, were consistently much higher than the compressive stresses required to cause even large strains at a confining pressure equivalent to the borehole pressure. Observations of the deformation and cutting processes in salt combined with results of finite-element analyses of rock and metal cutting explain the low sensitivity to borehole pressure of halite penetration rates and its relatively high specific energy.This study fills a gap in industry knowledge of pressure effects in drilling and sheds light on the processes involved in drilling rock salt. The key practical conclusions are that penetration rates and mechanical specific energy in salt are not greatly influenced by borehole pressure. Consequently, if a high borehole pressure is required to stabilise the wellbore through a salt formation, there is little penetration rate penalty to be paid, except perhaps if increasing the mud weight involves significant changes to the drilling fluid properties other than its density. The comparison of results from visual single point cutter and full-scale bit tests suggests, unsurprisingly, that reducing bit cutter density and modifying drilling fluid properties may both offer routes to ...

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Section: Discussionmentioning

confidence: 99%

The Effect of Borehole Pressure on the Drilling Process in Salt

Curry

Lourenco

Ledgerwood

et al. 2015

SPE/IADC Drilling Conference and Exhibition

View full text Add to dashboard Cite

show abstract

“…As a result of the combined problems of compaction disequilibrium and salt tectonics. complex stress patterns were created in the formations surrounding the salt structures which led to rubble zones and recumbent beds [10,11,12]. Therefore.…”

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confidence: 99%

Comparative analysis of drilling performance of kymera and PDC bits in salt formation

Clement

2020

BEN

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The study compares the drilling performance of Kymera and PDC bits in salt formation using River and Delta State Continental Shelf of Nigeria as a case study. The measurement while drilling (MWD) and the logging while drilling (LWD) methods were used to measure the real time well drilling operation. well formation and drilling statistics. The data obtained from the Ogbaimbiri. Ossiomo. Utorogu and Okporhuftu wells have the penetration rate of 6.2 m/hr. 5.9 m/hr. 12.2 m/hr. 6.3 m/hr for Kymera bit and 4.2 m/hr. 3.4 m/hr. 6.8 m/hr. 3.9 m/hr for PDC bit respectively. The pearson correlation coefficient has a value of r = 0.897. n = 4. p<0.05 and r = 0.784. n = 4. p<0.05 for both kymera and PDC bits. The results established a strong and positive correlation between the penetration rate and distance drilled in each bit. It also shows that the higher the penetration rate the more the distance drilled by each bit. The study concluded that the Kymera bit was more efficient as it was able to penetrate the different formations with a lesser time and at a greater penetration rate.

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The Effect of Borehole Pressure on the Drilling Process in Salt

Curry

Lourenco

Ledgerwood

et al. 2016

SPE Drilling &Amp; Completion

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Summary Wells penetrate long intervals of salt to access hydrocarbon reservoirs in many locations. High mud weights are frequently used to stabilize the wellbore while drilling through salt formations. High borehole pressures reduce rates of penetration (ROPs) in many sedimentary rocks. This effect is significant and contributes greatly to the low ROPs and high costs associated with deep drilling. This paper presents the results of an integrated laboratory study of the effect of borehole pressure on the drilling process in salt. The study included full-scale laboratory-drilling tests, visual single-point-cutter tests, and triaxial-compression tests. The drilling tests were performed by use of a polycrystalline-diamond-compact (PDC) bit and a synthetic-based drilling fluid typical of field practice. The visual single-point-cutter tests used a clear drilling fluid, enabling observation and video recording of the salt-cutting process at elevated borehole pressures along with simultaneous measurement of the cutting forces. The effect of borehole pressure on drilling salt is seen to be small; increasing borehole pressure does not reduce ROPs in salt as much as it does in many other sedimentary rocks. In contrast to other sedimentary rocks, salt deforms plastically to relatively large strains in compression without loss of mechanical integrity, even at low confining pressures. In addition, the shear stress to achieve a given strain does not increase greatly with confining pressure. Rock-cutting forces in the single-cutter tests increased only moderately as borehole pressure was increased from 300 to 6,000 psi. Full-scale bit-penetration rates also decreased by relatively small amounts over the borehole-pressure range investigated (1,000–6,000 psi). Mechanical-specific-energy (MSE) levels showed corresponding small increases. These levels, however, were consistently much higher than the compressive stresses required to make even large strains at a confining pressure equivalent to the borehole pressure. Observations of the deformation and cutting processes in salt combined with results of finite-element analyses of rock and metal cutting explain the low sensitivity to borehole pressure of halite-penetration rates and its relatively high specific energy. This study fills a gap in industry knowledge of pressure effects in drilling and sheds light on the processes involved in drilling rock salt. The key practical conclusions are that ROPs and MSE in salt are not greatly influenced by borehole pressure. Consequently, if a high borehole pressure is required to stabilize the wellbore through a salt formation, there is little penetration-rate penalty to be paid, except perhaps if increasing the mud weight involves significant changes to the drilling-fluid properties other than its density. The comparison of results from visual single-point-cutter and full-scale bit tests suggests, unsurprisingly, that reducing bit-cutter density and modifying drilling-fluid properties may both offer routes to increase ROPs in salt. The current study does not, however, investigate directly the effect of fluid properties on the drilling process in salt.

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Full-Scale Laboratory Study of the Impact of Drilling Fluid Composition and Properties on Penetration Rates in Brazilian Pre-Salt Carbonates

Cited by 7 publications

References 26 publications

The Effect of Borehole Pressure on the Drilling Process in Salt

The Effect of Borehole Pressure on the Drilling Process in Salt

Comparative analysis of drilling performance of kymera and PDC bits in salt formation

The Effect of Borehole Pressure on the Drilling Process in Salt

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