Surge and Drag Analysis for Extended Reach Casing and Casing Flotation Operations With Centralizers: A Design Challenge?

Samuel, Geoffrey; Mason, Colin

doi:10.2118/110700-pa

Cited by 3 publications

(1 citation statement)

References 9 publications

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“…Several studies have been done with regard to torque and drag [2,3,4] and only limited research has been carried out to estimate the pressure losses when complex geometries are associated with the stand-off devices. When these types of stand-off devices are used swab and surge pressures also need to be considered and must be maintained within narrow limits during tripping, casing running and cementing operations.…”

Section: Introductionmentioning

confidence: 99%

Annular Pressure Loss Predictions for Various Stand-off Devices

Yao

Samuel

2008

All Days

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During drilling and cementing operations, many stand-off devices, such as centralizers, stabilizers, reamers, turbulators, cutting bed impellers, and friction reduction devices are widely used. Some of these devices are designed to enhance the displacement efficiency during cementing operations, to increase hole cleaning efficiency, or to reduce torque and drag during drilling operations. The hydraulics program for the deep and especially ultra deep wells constitutes a significant portion of the well planning. Challenges associated with extreme depth and different types of downhole tools used in the drillstring translate to additional problems to the well design. Few studies have explored the pressure losses arising from these attached devices in the drillstring or casing string, and the pressure losses caused by them are assumed either negligible or ignored. The geometrical designs of these devices are relatively irregular and complicated, which is one of the major difficulties for pressure loss calculations. Non-Newtonian drilling fluids further complicate the problem. A study is necessary to determine the impacts of these devices on the pressure loss calculations and thereby the effects on downhole circulating density. These devices alter the flow stream and especially the angular bladed type cause the flow to swirl. This flow is complex, which underpins the effects of the pressure drop calculation across these devices. The paper describes a method and equations to calculate the pressure losses due to the stand-off devices.

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Section: Introductionmentioning

confidence: 99%

Annular Pressure Loss Predictions for Various Stand-off Devices

Yao

Samuel

2008

All Days

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Cementing Production Liners Terminating in Depleted Reservoirs: A Case Study on Deepwater Wells off the East Coast of India

Yadav

Kumar

Iyer

et al. 2018

SPE Asia Pacific Oil and Gas Conference and Exhibition

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A lightweight cement solution was successfully applied in deepwater wells at depths greater than 1000 m and in production liners terminating in depleted reservoirs. These wells were drilled off the east coast of India. The fracture gradient prognosis for the depleted zones ranged from 11.0 to 11.28 lbm/gal. The measured depth (MD) of these wells was more than 4500 m (MDRT). Mud weights ranged from 10.9 to 11 lbm/gal in the well while drilling the zone. The length of the liner normally ranged from 1400 to 2300 m. The cement slurry was finalized after conducting numerous tests in the laboratory. A lead and tail combination was used for the job to maintain the required equivalent circulating density (ECD). In openhole completions, the casing or liner before the gravel pack should be landed in sand to establish having reached the reservoir top and to help ensure that no shale is present. Challenges for a successful liner job in these wells include landing in a depleted reservoir, which would enable a very low margin between the mud weight and fracture gradient. This margin is further reduced by the minimum horizontal stress mud weight requirement to help ensure that no hole collapse occurs while drilling and before cementing begins. In addition to the depleted zone, to maximize reservoir tapping, the well profiles are highly deviated, often reaching a well deviation of 80+ degrees, resulting in a high ECD during cementing. A long section of the cement column can create problems of cement channeling past the mud and mixing in the annulus. The correct prediction of pore pressure and fracture pressure for different sections is very important. Accurate knowledge of these values is recommended for a correct job design. Some of the lessons learned during the process to help ensure good zonal isolation include the following: An 11-lbm/gal lightweight lead slurry was formulated, keeping ECD and fluid rheology vs. strength development in mind. Solids loading was controlled to help ensure low friction factors (considering rheology) and to achieve a final compressive strength of 2,000 psi because it was a production casing.The length of the tail slurry column was maintained to a minimum to create minimal effect on the ECD, even though the hydrostatic pressure developed was marginal in a highly deviated section.A low-rheology/low-density synthetic oil-based mud (SOBM) (10 lbm/gal) was pumped ahead to reduce the ECD and to maintain the equivalent static density (ESD) above the pore pressure. In addition, the displacement rate was staggered to help maintain the ECDs.A high-viscosity pill was spotted at the 12 1/4-in. section total depth (TD) before the final pullout to act as a base for the cement slurry. This paper highlights the concerns and best practices developed when cementing production liners across depleted formations in deepwater wells.

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Buoyancy Force on a Plain or Perforated Portion of a Pipe

Cayeux

Stokka²,

Dvergsnes³

et al. 2021

SPE Journal

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Summary Torque and drag models have been used for several decades to calculate tension and torque profiles along drillstrings, casing strings, and liner strings. Buoyancy forces contribute to the loads acting on the pipe and affect its interaction with the borehole wall. Torque and drag calculations account for these localized effects, as well as the material internal forces, torques, and moments on each side of the contact. When the analysis is applied to a discrete length of pipe, the cross sections at each end do not contribute to the buoyancy forces because they are not in contact with the fluid, except where there is a change in diameter or at the end of the string of pipe. We argue that it is important to check that the models used for solid pipe torque and drag calculations remain valid for sand screens, in particular, the extent to which the buoyancy forces acting on a perforated tube might differ from those on a solid pipe. Because the buoyancy force is the result of the pressure gradient acting on the surface of the pipe, the presence of holes may also influence the buoyancy force. We propose that there are theoretical differences between local buoyancy forces acting on plain or perforated tubes. This paper describes how to calculate the local buoyancy force on a portion of a drillstem by the application of Gauss’ theorem and accounting for the necessary corrections arising from the cross sections not being exposed to the fluid. We built an experimental setup to verify that the tension inside a pipe subject to buoyancy behaves in accordance with the derived mathematical analysis. With complex well construction operations, for instance during extended-reach drilling or when drilling very shallow wells with high buildup rates, the slightest error in torques and drag calculations may end up jeopardizing the chances of success of the drilling operation. It is therefore important to check that the basis of design calculations remain valid in those contexts and that, for instance, sand screens or slotted liners may be run in hole safely after a successful drilling operation.

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Surge and Drag Analysis for Extended Reach Casing and Casing Flotation Operations With Centralizers: A Design Challenge?

Cited by 3 publications

References 9 publications

Annular Pressure Loss Predictions for Various Stand-off Devices

Annular Pressure Loss Predictions for Various Stand-off Devices

Cementing Production Liners Terminating in Depleted Reservoirs: A Case Study on Deepwater Wells off the East Coast of India

Buoyancy Force on a Plain or Perforated Portion of a Pipe

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