Stable sliding preceding stick-slip on fault surfaces in granite at high pressure

1975 ◽  
Vol 113 (1) ◽  
pp. 63-68 ◽  
Author(s):  
J. D. Byerlee ◽  
R. Summers
Keyword(s):  
High Pressure ◽  
Stick Slip ◽  
Stable Sliding

Large-Scale Evaluation of Constrained Bearing Elements Made of Thermosetting Polyester Resin and Polyester Fabric Reinforcement

2006 ◽  
Vol 128 (4) ◽  
pp. 681-696 ◽  
Author(s):  
P. Samyn ◽  
W. Van Paepegem ◽  
J. S. Leendertz ◽  
A. Gerber ◽  
L. Van Schepdael ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Large Scale ◽  
Elastic Recovery ◽  
Small Scale ◽  
Practical Implementation ◽  
Fiber Failure ◽  
Stick Slip ◽  
Composite Surface ◽  
Pull Out ◽  
Stable Sliding

Polymer composites are increasingly used as sliding materials for high-loaded bearings, however, their tribological characteristics are most commonly determined from small-scale laboratory tests. The static strength and dynamic coefficients of friction for polyester/polyester composite elements are presently studied on large-scale test equipment for determination of its bearing capacity and failure mechanisms under overload conditions. Original test samples have a diameter of 250 mm and thickness of 40 mm, corresponding to the practical implementation in the sliding surfaces of a ball-joint, and are tested at various scales for simulation of edge effects and repeatability of test results. Static tests reveal complete elastic recovery after loading to 120 MPa, plastic deformation after loading at 150 MPa and overload at 200 MPa. This makes present composite favorable for use under high loads, compared to, e.g., glass-fibre reinforced materials. Sliding tests indicate stick-slip for pure bulk composites and more stable sliding when PTFE lubricants are added. Dynamic overload occurs above 120 MPa due to an expansion of the nonconstrained top surface. A molybdenum-disulphide coating on the steel counterface is an effective lubricant for lower dynamic friction, as it favorably impregnates the composite sliding surface, while it is not effective at high loads as the coating is removed after sliding and high initial static friction is observed. Also a zinc phosphate thermoplastic coating cannot be applied to the counterface as it adheres strongly to the composite surface with consequently high initial friction and coating wear. Most stable sliding is observed against steel counterfaces, with progressive formation of a lubricating transfer film at higher loads due to exposure of PTFE lubricant. Composite wear mechanisms are mainly governed by thermal degradation of the thermosetting matrix (max. 162°C) with shear and particle detachment by the brittle nature of polyester rather than plastic deformation. The formation of a sliding film protects against fiber failure up to 150 MPa, while overload results in interlaminar shear, debonding, and ductile fiber pull-out.

An Innovative Design for Drillstring Testbed for High Pressure High Temperature Drilling

2020 ◽  
Author(s):  
Randall Tucker ◽  
Alan Palazzolo ◽  
Mohamed Gharib
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Simulation Software ◽  
Operating Conditions ◽  
Dynamics Simulation ◽  
Drilling Fluids ◽  
Test Rig ◽  
Stick Slip ◽  
Rock Interaction ◽  
High Pressure High Temperature

Abstract In this paper, a novel design for a full-scale, industrial-size, and high pressure high temperature (HPHT) drillstring test rig is presented. The test more accurately replicates the downhole environment with regards to bit performance limiters. The facility has a high-power drill string with side loading, reasonably sized mud pumps, a HPHT sample that generates a hot pressurized rock-bit interface and the ability to easily replicate specific drilling scenarios. This provides a step change in drilling research. Replicating down-hole HPHT conditions in a surface level drilling test rig is challenging but will deliver significant benefits for downhole tool and instrument development. The proposed test rig will provide these test conditions for developing longer lasting and more efficient bits, more effective drilling fluids, and lower friction tool joints to increase weight on bit (WOB) and rate of penetration (ROP). A secondary benefit is for identification of bit-rock interaction laws that will assist in implementing successful automated drilling (AD) approaches to reduce drillstring and bit failures from stick-slip, bit-bounce and other drilling anomalies. AD has the potential for increasing efficiency as well as reliability of drilling. The force and torque laws will also be utilized in drillstring dynamics simulation software for operator training and hardware development. The proposed test rig gives the industry a unique opportunity to couple experimental work that is representative of downhole conditions with actual industry problems and concerns. By using data sets from actual drilling operations, we will be able to replicate what is occurring downhole but in a controlled, measurable environment on the surface. The system will be highly automated with a remotely operated control room, to increase safety in the high temperature, pressure, force and torque environment of the test rig. The system is to be fully enclosed with an API rated pressure containment system. The description of the test rig here is intended to convey the complexity of the hardware needed to meet functionality requirements and operating conditions. The design is purposely configured to accommodate the inevitable small requirement modifications, with minimal delays in rig completion.

Field Application of Reaming-While-Drilling Technology in the Super Deep Composite Anhydrite-Salt Layers of Kuche Mountain Front in Tarim Oilfield

2021 ◽  
Author(s):  
Zhixiong Xu ◽  
Xueqing Teng ◽  
Ning Li ◽  
Hongtao Liu ◽  
Caiting Zhao ◽  
...  
Keyword(s):  
High Pressure ◽  
Salt Water ◽  
Geological Structure ◽  
Drill String ◽  
Field Application ◽  
Salt Rock ◽  
Stick Slip ◽  
Rock Creep ◽  
Mountain Front ◽  
Drilling Technology

Abstract The implementation of drilling technique for multiple lithology interbeds and high-pressure anhydrite-salt in the complex Mountain Front area has been completed. The plastic creep of the anhydrite-salt layers, the losses of the low-pressure sandstone, the overflow of the high-pressure salt-water, the narrow mud density window and frequent pipe-stuck occurrence are significant issues, which trigger significant engineering challenges downhole. This study presents the application of the reaming-while-drilling (RWD) technology which has led to minimize the downhole non-productive time (NPT) and achieve successful results. The RWD technique was applied in the composite anhydrite-salt formation of the Kumugeliemu group. Through optimized combination of the RWD tools, bits, reaming blades, and the mechanical analysis the drill string with shock-absorbing design and hydraulics optimization to guarantee the bit and the reamer blades have the proper pressure drop, hydraulic horsepower and flow-field distribution, the RWD was used with the vertical seeking tool drilling technology, resulting in minimum vibration and/or stick-slip, and achieving the expected rate of penetration (ROP) as well as target inclination. It improved the operation efficiency significantly while avoiding the downhole complexities at the same time. Since the geological structure of the offset well Keshen X (no RWD) is similar to Keshen XX (RWD technology was applied), a comparison between the two wells was performed. The reaming meterage in the composite anhydrite-salt layers in Keshen XX was 791 m, spending 15 days, average ROP is 3.73 m/hr. There was no overflew or loss during the drilling. It was smooth, no pipe sticking when checking the reaming effect during the wiper trip and the tripping out. On the other hand, Keshen X spent 29 days with average ROP of 1.35 m/hr to drill the 449 m composite anhydrite-salt rock. Moreover, it was difficult to trip in and trip out during the drilling, and the pipe sticking happened frequently, back-reaming frequently as well. There were losses during both the drilling and the casing running. Due to the unsmooth wellbore, this well increased additional 3 runs of reaming after drilling operation and 4 clean-out runs. 13 days later after the reaming operation, the anhydrite-salt rock creep was checked and found that the hole was still smooth, no pipe sticking existing. Hence, RWD technology has accomplished both goals of preventing the downhole complexities and speeding up drilling. The novel RWD technology can be well illustrated by presenting all the details of its application in salt-base formations.

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