Slickline Calculators
Four slickline calculators for the common wire sizes 0.092, 0.108, 0.125, 0.140 and 0.160 in. Breaking strengths come from published manufacturer tables and vary by manufacturer.
Educational quick-check calculators: not an approved procedure and not a substitute for your company software or a qualified engineer’s review.
Wire stretch and free point
Free wire length above the stuck point from the pull difference and measured stretch.
How it is calculated
L (ft) = E · A · ΔL / (12 · ΔF)
Stretch constant = 12 × 10⁶ / (E · A) [in per 1,000 lbf per 1,000 ft]
Assumptions
- Straight wire, no friction, elastic range. In deviated wells the real free length is longer.
- E is about 30×10⁶ psi for carbon wire; stainless and alloy wires differ, so use the value on the wire certificate.
- Area from the nominal diameter; a worn wire stretches more.
Worked example
0.108 in wire (A = 0.009161 in²), ΔF = 200 lbf, ΔL = 36 in, E = 30×10⁶ psi → L = 30×10⁶ × 0.009161 × 36 / (12 × 200) = 4,122 ft.
Sources: Baker Hughes — Tech Facts, general stretch formula (Hooke’s law, E = 30×10⁶ psi for steel) · IWCF Well Intervention Pressure Control syllabus (wireline operations)
Educational quick-check tool, not an approved procedure. Follow your company procedures and the manufacturer’s data.
Safe working load by wire size
Nominal breaking load from the manufacturer table ÷ safety factor, then the pull left at the tool after the wire weight.
How it is calculated
W_wire = (lb per 1,000 ft) × L / 1,000
Pull available at tool ≈ SWL − W_wire
BL (lbf) IPS / EIPS / 316:
0.092: 1547 / 1830 / 1430 0.108: 2109 / 2490 / 1960
0.125: 2794 / 3300 / 2640 0.140: 3578 / 4002 / 3325
0.160: 4606 / 5107 / 4175
lb/1000 ft (carbon): 22.7, 31.1, 41.9, 52.0, 68.5
Assumptions
- Values from published Danum Well Services (Bridon) tables; IPS values are the API 9A minimum. Values vary by manufacturer, so use your wire certificate.
- Wire weight in air (conservative); excludes friction, stuffing box and the weakening of a worn or knotted wire. The safety factor is your company’s decision; Danum recommends no more than 60% of actual breaking load when jarring and 70% for straight pulls.
Worked example
0.108 in carbon EIPS (BL = 2,490 lbf), SF = 2, 10,000 ft → SWL = 1,245 lbf (50%), wire weight = 31.1 × 10 = 311 lbf, available at the tool = 934 lbf.
Sources: Danum Well Services — Carbon, Stainless and Alloy Slicklines: Physical Properties (EIPS, 316 breaking loads; weights) · Danum Well Services product catalogue / Bridon IPS data (API 9A minimum: 1547, 2109, 2794, 3578, 4606 lbf) · API Spec 9A (wire rope and measuring wire)
Educational quick-check tool, not an approved procedure. Follow your company procedures and the manufacturer’s data.
Buoyed tool string weight
Tool string weight in the well fluid from fluid density and tool metal density.
How it is calculated
BF = 1 − SG_fluid / SG_tool
W_buoyed = W_air × BF
Assumptions
- Tool fully submerged in one fluid, no friction. Typical densities: steel 7.85, lead 11.34, tungsten alloys about 17 to 18.5 (varies by manufacturer).
- In gas the fluid density is close to zero and BF ≈ 1.
Worked example
150 lbf in air, 8.6 ppg fluid (SG = 1.0305), steel 7.85 → BF = 1 − 1.0305/7.85 = 0.8687, buoyed weight = 130.3 lbf.
Sources: Archimedes’ principle; Bourgoyne, A.T. et al. — Applied Drilling Engineering (buoyancy factor) · CRC Handbook of Chemistry and Physics (density of lead 11.34 g/cm³); manufacturer data for tungsten alloys
Educational quick-check tool, not an approved procedure. Follow your company procedures and the manufacturer’s data.
Minimum tool string weight against wellhead pressure
Well pressure pushes the wire out through the stuffing box with a force equal to pressure × wire area; the tool string must overcome it plus friction.
How it is calculated
F_pressure = WHP × A
W_min,buoyed = F_pressure + F_friction
W_min,air = W_min,buoyed / BF ; BF = 1 − (ρ/8.3454) / SG_tool
Assumptions
- The friction allowance is your choice (50 lbf is only an example); it depends on packing type, tightening and wire condition. Many companies add an extra margin on top.
- Excludes the weight of wire already in the well (which helps the descent) and friction in deviated wells.
Worked example
3,000 psi, 0.108 in wire (A = 0.009161 in²), 50 lbf friction, tools in gas → pressure force = 3,000 × 0.009161 = 27.5 lbf, minimum weight = 27.5 + 50 = 77.5 lbf.
Sources: IWCF Well Intervention Pressure Control syllabus (wireline: tool string weight vs well pressure on the wire) · Force = pressure × area (wire cross-section from nominal diameter)
Educational quick-check tool, not an approved procedure. Follow your company procedures and the manufacturer’s data.