Development of Free Point Indicator (FPI) Tool

Free Point Indicator (FPI) Tool is a tool that identifies the free point in a stuck pipe string. The FPI tool measures the stretch in the pipe caused by applied force. A wireline engineer will attach the tool to the pipe downhole, ask the rig to apply a pull force or torque, and the tool will indicate where the pipe begins to stretch. This is the free point–above this, the pipe is free to move, while below this point, the pipe is stuck.

Traditional Free Point Tools

Often referred to as legacy tools, these are equipped with a strain gauge that precisely measures tiny changes in pipe stretch, compression, and torque applied from the surface by the rig. The strain gauge, once set, is anchored to the pipe's internal diameter, unhindered by cable influence, and can measure stretch and rotational deflection. However, the data sent to the surface panel is only representative of the tubing status at the depth of the strain gauge. Consequently, several station stops must be conducted to accurately identify the depth at which the pipe is stuck. Each station stop necessitates the rig to apply stretch and torque to determine the pipe's status at the set depth of the free point indicator.

The New Generation Free Point Tools

On the other hand, the new generation Free Point tools take advantage of the magnetoresistive property of steel. The tools are equipped with sensors that alter their resistance in relation to external magnetic fields and record the results. Known as the Halliburton Free Point Tool (HFPT), it identifies and records the point where the pipe is stuck, presenting the data in a digitized log format. The HFPT requires only one application of pull or torque in straight vertical well bores to induce stress in the pipe, which modifies the pipe material's magnetic characteristics above the stuck point. This data is then logged and digitally recorded, allowing for later review and analysis of the stuck point.

The Procedure Using The New Tool

The procedure using the new tool calls for two logging passes. The first logging pass records magnetization about the pipe with the pipe in a neutral weight condition (the baseline). The second logging pass records magnetization with tension or torque applied to the pipe. When torque or tension is applied to pipe that can be stretched or torqued, its magnetostrictive properties change. If a section of the pipe cannot be stretched or torqued, magnetization effects remain unchanged. It's by this principle that the free point — the transition between the pipe that can and cannot be stretched or torqued — is easily identified through the comparison of the two logging passes.

Previous free point determination methods required a series of stationary measurements with the pipe in a neutral weight condition and then with the application of stretch or torque and required a highly skilled pipe recovery expert on location. The new method simply involves an overlay of two logging passes before and after the pipe has been stretched or torqued.

However, highly deviated or horizontal wells may require additional pulls or turns of torque to stress the pipe enough to identify the stuck pipe depth. Remember, in all these methods, it's vital to carefully monitor the changes in the force applied and the resulting changes in the pipe (stretch, twist, etc.). Moreover, all these methods have their limitations, and the results can be affected by various factors like temperature, pipe fatigue, mud weight, etc. Therefore, it's crucial to interpret the results with caution and consult with experienced professionals.

This method of employing the FPI tool can be used hand-in-hand with the stretch calculation method to narrow down the estimate stuck point location. It will reduce time and log interval needed to accurately pinpoint the exact location with the FPI tool.

Once the stuck point is determined, various strategies can be employed to free the pipe, including the use of drilling fluid to reduce pressure, acid pumping, jarring operations, or even pipe severing in extreme cases. The chosen method will depend on the exact circumstances of the stuck pipe.

Vigor's Memory Cement Bond Tool is specifically designed to assess the integrity of the cement bond between the casing and the formation. It accomplishes this by measuring the cement bond amplitude (CBL) using near receivers positioned at both 2-ft and 3-ft intervals. Additionally, it utilizes a far receiver at a distance of 5-ft to obtain the variable density log (VDL) measurements.

To ensure a comprehensive evaluation, the tool divides the analysis into 8 angular segments, with each segment covering a 45° section. This enables a thorough 360° assessment of the cement bond's integrity, providing valuable insights into its quality.

For those seeking customized solutions, we also offer an optional compensated sonic Cement Bond Tool. This tool can be tailored to meet specific requirements and boasts a compact structure design, resulting in a shorter overall length of the tool string. Such characteristics make it particularly suitable for memory logging applications.

For more information, you can write to our mailbox info@vigorpetroleum.com&marketing@vigordrilling.com