A realistic maintenance schedule should be focused on three areas: early detection of wear or damage, cleaning the tool and associated components, and maintaining the jar as suggested for the application. When arranging a service the operating circumstances including temperature, well trajectory, drilling duration, vibration and BHA configuration should be considered.
Proper Maintenance Techniques for Drilling Jars
A sound maintenance program may assist in the detection of issues before they impede drilling operations. The inspection should not be confined to the period when a tool is readied for a run. The drilling jar should also be inspected once it is removed from the hole, especially if it has been subjected to lengthy operation or severe downhole conditions.
Regular Inspection and Cleaning
Inspect the drilling jar before and after each run in accordance with the inspection protocol prescribed for the specific model. Inspect the mandrel, housing, connections, seals, exposed surfaces and any other components listed in the manufacturer’s maintenance manual.
eliminate the tool from the hole and clean it well to eliminate the drilling fluid, cuttings and other pollutants. Cleaning is especially necessary in regions near ports, bores and other locations where material might interfere with inspection or service.
For instance, SLB’s Hydra-Jar AP operating procedures recommend cleaning the jar with fresh water after each trip out of the hole, and certain cleaning instructions for the mandrel bore, fluid cylinder, neutralizer cylinder and lower-sub bore. The procedure also involves emptying drilling fluid from the relevant ports and holes before putting the tool back into service.
If the tool shows signs of abnormal operation, leakage, excessive wear or impact damage, visual inspection alone should not be relied upon. In these cases the jar must be assessed to the applicable service procedure before returning it to the drill string.
Lubrication and Fluid Management
Lubrication and hydraulic-fluid management should be performed per the jar manufacturer’s instructions, not by adding a universal lubricant or fluid to all parts.
The correct functioning of hydraulic drilling jars is dependent on the quality and management of the internal hydraulic system. Tool performance might be affected by contaminated fluids, poor fluid management or seal difficulties. Service workers should consequently apply the prescribed fluid, filling technique and inspection method for the specific jar.
Some components or surfaces may also need external lubrication. For example, SLB's Hydra-Jar AP processes include cleaning certain mandrel areas and greasing them after cleaning. Always use the correct lubricant, correct application point and correct servicing technique according to the corresponding tool instructions.
If there is any sign of leaking from seals, plugs or other fluid retention parts, the tool should be checked before the next run rather than just topping up the lubricant or fluid and restoring it to service.
Calibration and Adjustment
Drilling jar parameters should never be changed on a calendar basis. Jar design, operational application and manufacturer’s specifications all play a role in determining adjustment and testing needs.
Where the jar is supplied with adjustable impact or release settings, the proper setting should be determined in accordance with the proposed drilling application and the rated operating parameters of the tool. Some changes are meant to be done at a service center, not at the rig site.
Testing is a crucial element of service, too. NOV’s jar-testing equipment is intended to confirm the functioning condition of drilling and fishing jars by applying controlled tension or compression and documenting the test results.
A good servicing program should involve examination, testing when needed, and documenting of the condition of the tool before being returned to the drill string.
Optimizing Drilling Jar Performance in Harsh Environments
Downhole temperature, pressure, well trajectory, drilling fluid conditions, vibration, and mechanical loads may impact drilling-tool performance. The selection and use of a drilling jar for severe service applications should be within the rated limitations.
Maintenance planning should be based on real operating circumstances and not on one service interval for all the wells.
Temperature Management
Temperature is a major factor for hydraulic drilling jars since it may damage the hydraulic fluid, seals and other internal components.
For high temperature applications, ensure that the chosen drilling jar and its associated components are acceptable for the projected downhole environment. Service intervals should also be determined according to the manufacturer’s recommendations for the particular tool and application.
For example, the SLB’s Hydra-Jar AP literature suggests that the suggested change-out intervals depend on such parameters as jar size, duration in the hole, hole size and bottom-hole temperature. This explains why the service planning should be application specific rather than calendar time based.
Corrosion Prevention
Exposed surfaces, connectors, seals, etc. may be damaged by corrosive downhole conditions. If corrosion is a problem, the drilling jar should be chosen and maintained to the materials and environmental restrictions stated by the manufacturer.
After a run, check the tool for corrosion, surface damage or other changes that might impair its condition. Particular care should be taken to those regions where contaminants or drilling fluid might be left behind after the instrument is withdrawn from the hole.
If a component is found to be excessively corroded or damaged, it should be inspected and serviced in accordance with the applicable method before the jar is reused.
Vibration and Shock Mitigation
A drilling jar is meant to provide a regulated impact but the tool is also subjected to stresses caused by drilling, rotating, BHA movement and the wellbore geometry. Too much vibration or the BHA being in the wrong spot creates mechanical stress.
Hence the placement of jars is a crucial aspect of performance management. SLB comments that jar location is important and should be re-evaluated if BHA configuration or weight-on-bit circumstances change. Its operation guidelines also include explicit advice as to the location of the stabilizers and the connection between the jar and the neutral point.
The drilling jar should be placed as recommended by the manufacturer and as intended for the BHA design. Don’t make placement one choice if circumstances or the BHA change during drilling.
Innovative Technologies Enhancing Drilling Jar Longevity
Technology may aid in improving drilling jar dependability, however not all drilling jars need or support the same method to monitoring or maintenance. The most beneficial technology is one which gives accurate information about the status of a tool, its operating parameters or its servicing needs.
Smart Monitoring Systems
Where the drilling system allows for this capacity, digital monitoring may offer extra information on downhole conditions and tool operating.
For example, SLB’s D-Jar is a digital downhole adjustable jar that allows surface-controlled operation and gives real-time indication of tool condition. It also employs downhole measurement to detect jarring force, which can be recalibrated in situ.
We believe these technologies are answers to particular applications, not elements of every drilling jar. Where monitoring equipment is available the data generated may supplement normal inspection and servicing processes.
Advanced Materials and Coatings
Material selection is of great importance in the design of drilling jars, since they are exposed to mechanical stress and the downhole environment.
Modern drilling jars may be made from high strength materials. They may have unique surface treatments or be designed with protective features for specific service circumstances. NOV, for example, specifies drilling jar designs meant for demanding applications and promotes characteristics such as high-yield mechanical structure, pressure-retaining systems, and protective materials in its drilling jar portfolio.
However, material or coating must be chosen depending on unique well conditions and tool design. A coating or substance is not a replacement for inspection proper functioning or periodic service.
Automated Maintenance Systems
Automation may minimize the human effort in certain sections of the drilling process, however automation of cleaning or lubrication should not be sold as a maintenance solution for all drilling jars.
The most important maintenance operation for most drilling jars is inspection, cleaning, testing and service according to the manufacturer’s standards. Where available, the necessary service requirements should be supplemented, but not replaced, by the use of automated monitoring or maintenance equipment.
A recorded maintenance history may also assist drilling crews monitor tool condition, service intervals, past repairs and operating circumstances. The information may help make more consistent maintenance choices across repeated runs.
Conclusion
To extend the life of a drilling jar, the maintenance plan should correspond with the tool design and the real drilling environment. More dependable solutions than the use of a universal maintenance plan include regular inspection, effective cleaning, suitable fluid and lubrication procedures, appropriate testing and proper service.
The circumstances of operation are also important. Temperature, vibration, BHA design, well trajectory and time in the hole may impact how a jar should be maintained and when it should be serviced. The manufacturer's guidelines should consequently be the primary source for service intervals, adjustment methods, fluid needs, and operating restrictions.
Proper positioning of jars is also vital. The tool design and well specifications should determine that the BHA is equipped with a drilling jar. Placement should be reassessed, not assumed to be adequate based on the initial configuration when the BHA or drilling parameters change.
A structured approach of maintenance and inspection helps drilling crews catch issues sooner, keep tools performing better and make better judgments on when a drilling jar should be fixed or put back into action.
Call to Action
The selection and maintenance of the correct drilling jar needs knowledge of drilling application, BHA setup, operating circumstances and tool parameters. Welong can walk you through your needs and help you choose an appropriate drilling-tool solution depending on your application.
When you contact Welong you may supply us with information such as the drilling jar type you want, tool dimensions or connection requirements, well conditions and intended use. Such knowledge may make the technical conversation more precise and beneficial.
For product information or to discuss your drilling requirements, contact Welong at oiltools15@welongpost.com.
