Effects of Selected Mud Properties on Rate of Penetration in Full-Scale Shale Drilling Simulations

Cheatham, C.; Nahm, J.J.

doi:10.2118/13465-ms

Cited by 18 publications

(4 citation statements)

References 6 publications

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“…Other studies conducted with roller cone bits show large fractional reductions in penetration rate with increasing borehole pressure. Cheatham, Nahm and Heitkamp (1985) reported penetration rates in Mancos shale at 4,000 psi borehole pressure which were 33 to 60% lower than those at 1,000 psi borehole pressure, with the fractional reduction in penetration rate increasing as weight on bit increased. An extreme case, admittedly in tests performed with a microbit as opposed to a full size bit, is that reported by Cunningham and Eenink (1959).…”

Section: Discussionmentioning

confidence: 91%

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: 91%

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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“…Cheatham et al 4 studied the influences of BHP and mud composition on the drilling response of Mancos shale. The pore pressure was not measured but was assumed to be atmospheric, so that differential pressure was thought to be approximately equal to BHP.…”

Section: Discussionmentioning

confidence: 99%

Influence of Pore Pressure on Drilling Response in Hard Shales

Gray-Stephens

Cook

Sheppard

1994

SPE Drilling &Amp; Completion

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Results are presented from laboratory drilling studies of two different hard shales similar to those found in some areas ofthe North Sea. Two laboratory drilling machines with milled-tooth bits were used. Pore pressure was measured in all the experiments, and in some it was reduced to several megapascals below bottornhole pressure (BHP). Pore-pressure reduction was achieved by allowing the pore fluid to drain out of the shale while external stresses were maintained constant. The influence of BHP was studied for values from 3 to 33 MPa [435 to 4,786 psi]. The differential pressure, which equals BHP minus pore pressure, ranged from near balance to > 10 MPa [> 1,450 psi]. BHP was found to have a strong influence on drilling response, but differential pressure did not, contrary to conventional wisdom. The results are compared with other drilling experiments and single-cutter experiments in the literature.

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“…(Cheathem et al, 1985) Bit hydraulics and hydraulic Horse power are also affected by mud weight. Density of the drilling fluid affects the rate of penetration in adverse manner.…”

Section: Effect Of Mud Weight On Drilling Rate (Rop)mentioning

confidence: 99%

Optimized Unconventional Shale Development With MPD Techniques

2013

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The rapid development of unconventional energy plays such as shale oil & gas necessitates "assembly line" approach to well construction and completion technologies. Due to very high number of wells being drilled to explore such promising resources, novel approach to optimize well construction process is necessary. This requires an industrial engineering approach to not only remove non-productive time out of the assembly process, but also drive out the invisible flat time and unrealized inefficiencies of the manufacturing process. This paper will discuss the application MPD to maximize drilling efficiency by optimizing drilling parameters to minimize Mean Specific Energy (MSE) for drilling.Managed Pressure Drilling (MPD) techniques have gained industry wide acceptance for drilling technically challenging prospects and also helping to minimize risks associated with well control and lost circulation hazards. The well construction process in shale plays might be perceived as more benign than some of the challenging environments such as deep-water. However application of MPD to maximize drilling efficiency in shale plays can minimize cost by reducing the field development time.MPD has been shown to reduce the drilling time by almost 50% through the elimination of known and unknown drilling inefficiencies. Overall drilling performance is impacted through the inherent ability of MPD to quickly identify and control any pressure events and continue drilling versus spending costly time fighting down hole problems. MPD also significantly impacts performance through the optimization of parameters such as mud weight and Equivalent Circulating Density (ECD).MSE has been a great tool to quantify drilling efficiency. Effect of different drilling parameters such as mud weight, weight on bit and torque on MSE will be discussed. Application of MPD has significant impact on MSE during drilling. This paper will describe how the use of MPD on shale developments, along with other unconventional developments improves the overall drilling efficiency hence allowing for quicker & safer well construction and field development. It will also investigate the added benefit of MPD improving field production through better understanding of productive zones and fracture identification.

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Effects of Selected Mud Properties on Rate of Penetration in Full-Scale Shale Drilling Simulations

Cited by 18 publications

References 6 publications

The Effect of Borehole Pressure on the Drilling Process in Salt

The Effect of Borehole Pressure on the Drilling Process in Salt

Influence of Pore Pressure on Drilling Response in Hard Shales

Optimized Unconventional Shale Development With MPD Techniques

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