Wireline Integrity Inspection Methods to Prevent Wire Breakage
Authors: Fehrmann G.Z. , Smith E.J. , Gibling G.R. 
Published: March 2010

The structural integrity and predictable usability of slickline wire has perplexed wireline crews since wireline services were first developed. Miscalculation of wire condition can cause wire failures and costly fishing operations. However, the available alternative-premature replacement of still-usable wire to avoid the first scenario-increases operational costs, especially when the newer corrosion- and embrittlement-resistant nickel and cobalt alloy wires that are commonly used in H2S, CO2, and hot chloride environments are involved. These wires often are ten times as costly as carbon steel and stainless steel alloy wires, and in most cases,. early replacement would not be economically feasible. Until recently, operators have had to rely on experience, "rules of thumb," visual inspection, and destructive tests to determine wire integrity. However, these methods could only provide spot checks; no methods have been capable of accurately assessing the condition of the entire length of spooled wire.

This paper will review currently used inspection procedures and a concept that incorporates an existing, non-destructive material inspection technology into a real-time method that can provide the information to determine wire condition over its entire length.

Use of this eddy current system can:Evaluate integrity of new wire as it is being spooled onto the reel.Avoid costly replacement of still-usable wire.Facilitate general wire-life assessment.Inspect wire during critical service operations where well environment or operating conditions can cause rapid degradation of the wire.

Test results and field operational history are used to illustrate the capabilities and significance of the system.

Introduction

Slickline is a single-strand wire that can be made of various carbon steel, stainless alloy, and more exotic nickel and cobaltbased alloys and is available in varying lengths and diameters. Slickline lengths are generally between 4,572 to 9,144 m (15,000 and 30,000 ft.), and the most popular outside diameters (OD) are 2.34,2.67,2.74, and 3.18 mm (0.092,0.105,0.108, and 0.125 in.).

"Braided line," "mono-conductor," or "multi-conductor" electric wireline consist of braids or multiple strands of smaller-OD wire, which are also available in various carbon steel, stainless and more exotic alloys in varying lengths and diameters. Braidedline and mono-conductor line lengths are generally between 4,572 to 7,620 m (15,000 and 25,000 ft.) with outside diameters of 4.76 or 5.56 mm (3116- or 7h2-in.). Multi-conductor line lengths are generally between 4,572 to 7,620 m (15,000 and 25,000 ft.) with outside diameters of 11.11 or 11.90 mm (7116- or 15h2-in.).

Typical Wireline Operation

In a wireline operation, tools are attached to the end of a wire and lowered into the wellbore. Once the tools reach their desired depth, they are manipulated in a series of upward and downward motions to perform the desired operation.

The wire is stored on a reel in a truck or skid and is generally run through or around a counter wheel and several sheaves (Figure 1). The counter wheel is used to measure the length of the wire deployed into the well.