Schlumberger Wireline - Unintentional Pull Off Prevention (UPOP)

Oil Field Service - Wireline UPOP

Introduction

The e-Learning Document is mainly intended to cover TECHNICAL KNOWLEDGE of tools and services that are not covered or partly covered in the Standard Work Instruction (SWI). It is not Intended to cover Job Process “Design”, “Prepare”, “Execute” and “Close”. The SWI is the standardized document for all job design, preparation, execution and close procedures.

Objectives

By the end of the module the trainee should be able to :

•Categorize the different types of UPOs (Unintentional Pull Off)

•Recognize the common causes of UPOs in Schlumberger Operation

•Identify and Understand the HSE risks related to UPOs

•Identify and Understand the Quality and Business consequences of UPOs for Schlumberger and clients

•Recognize the preventive and mitigation procedures and tools available

•Become familiar with the relevant standards and  Standard Work related to UPOP (Unintentional Pull off Prevention)

      In order to understand what is an unintentional Pull off lets review a general P.S. logging set up.  Logging unit is located in an area that will allow for the required operation, then Basic Equipment which composed of: Sheave Hanger, Sheave wheels, Chain, Sling, and Pressure control equipment are rigged up and finally Logging Cable is feed through.  

     To assemble the required string a logging head is attached to the cable, this equipment acts as the mechanical and electrical connection between cable and tools, once head is installed the string can be connected and lowered into the well. Of this setup the Basic Rig up Equipment handles the force generated by the cable weight , tool weight and friction forces  when string is in movement. 

     The force seen by the top sheave will be twice the current tension, while the tension seen at the lower sheave will be a function of the angle  and current tension. For this reason the Safe working load for the equipment is higher than the specifications of the cable.  

     The wireline cable as our conveyance method will see the force  generated by the cable weight , tool weight and friction force when the string is in movement; the Maximum strength will depend type the being used , you can find this on the tool planner in the cable properties  tab, Safe Working Load is the value used as the maximum tension that a cable can be exposed to.

Wireline Conveyance System

What is a UPO? Whenever a weakpoint or cable is broken unintentionally

What are the consequences of a UPO?

Client: Loss production, revenue, Damage to 

Equipment

Schlumberger: Loss of revenue, reputation, 

Loss /Damage to Equipment

YOU: Zero Tolerance….

Lihat Video Cable Structure dibawah ini:

TIME  for  TENSION   Buildup

§Example 1

–Tool at 10,000 ft and speed of 1000 ft/hr.  With a stuck tool, a 2500lbs increase in tension will take?

–18 feet of cable stretch and 1 minute.

§Example 2 

–Tool coming to surface at 1000 ft/hr with 150ft of cable from the truck to the lubricator.  When bumping up, a 2500lbs increase in tension (which is enough to risk breaking a weak point) will take?

–3 1/3 inches of cable stretch and 1 second.

PULL OFF PREVENTION

➤Pull Off Analysis

➤Pull Off – Cases for revision

➤TIME for TENSION Buildup

➤Pull Off PREVENTION

–WP Calculations

–WP Selection

–Prevention Tools

–Surface Checks

–Winch Operator’s notes

➤Operations

–Speed Limits

–RIH, POOH

➤Case Study and Scenarios

 Weak Point Selection Premises

1. Make sure you can pull off without breaking the cable (Respect the cable SWL)

•

2. Choose the largest Weakpoint suitable for the job

Weakpoints

§Rigid Modular Weakpoint

§Flexible Weakpoint

§Spider Weakpoint

§ECRD

TABLE-Rigid Modular Weakpoints

Rigid Weakpoints are identified with color code and written rating.  

Don’t trust the color coding system when installing or checking a weakpoint, 

always look for the rating that is stamped on it.  

TABLE- Flexible Weakpoint

➤Solid  (Rigid) weakpoints are more susceptible to damage to high shock, as in

 perforating jobs, than flexible weakpoints.

Spider Weakpoint (CH)

➤Technique sensitive!

➤The impact strength of a spider weakpoint decreases as the number of inner

armours decrease.

➤When a spider rope socket make up torque is increased beyond the

recommended value, it will cause the impact strength to decrease.

Weak Point Reduction with Temperature

§Solid weakpoints experience a ~ 4% strength reduction per 100 DegF increase

from room temperature (75 DegF). The effect  is not cumulative, that is, the

weakpoint recover its full strength when returned to room temperature.

Weak Point Selection

1.Make sure you can pull off without breaking  the cable (Respect the cable

SWL).

2.Choose the largest Weakpoint suitable for the job.

Upper WP rating (temp corrected) < 1/2 cable strength Ŧ - cable weight (in mud)

Ŧ SWL = 50% of Cable Ends Fixed Break Strength

Pull Off Prevention – Maximum Safe Pull

Max. Safe Pull =  Normal Tension - Wt. of Tool in Fluid + .75 (Lower WP Rating)

➤Max Pull  by FE without Consulting District Manager:

–75% of Lower Weakpoint Rating

–50% of Ends Fixed Break Strength

➤Know Your Normal Logging Tension

➤Consider effects of DRAG

•Temperature Effects

•Buoyancy Effects

Maximum Safe OverPull

MSOP is constant throughout the jobŦ

Ŧ Only if temperature remains fixed

Communication

➤Hand Signals

➤Intercom (UKI)

➤Radios

(to be continued)