Wireline Cable Protection Enabled a Safe and Efficient Formation Evaluation Programme On a Highly Challenging Well In Asia

Overview

Objective

  • To perform reservoir sampling on wireline in a 674 m
    5 deg deviated open hole section.

Challenges

  • Severe wireline cable sticking from past experience
  • Multiple sands in the dogleg with approx. 1,000 psi overbalance.
  • High cable thrust zone below casing shoe.
  • No wiper trip prior logging

Solutions

  • Conducted a risk assessment with Wire-Pro to quantify cable keyseating and differential sticking risks
  • WLSO were deployed across the risk zones

Result

  • 100 % Operating Efficiency
  • ZERO NPT
  • ZERO HSE Incident
  • ZERO Overpull

Details

A major oil and gas operator in Asia plans to drill and complete a number of development wells in a mature offshore oil field block. Formation evaluation using wireline logging has been included as part of the critical factor in the development of this field.

Historically, in this field, there have been incidents of wireline cable sticking which escalated to fishing. The accepted standard solution has been to run logs using Pipe-Conveyed-Logging, which significantly increased operating costs

A new approach was proposed to introduce the  latest wireline analysis modelling (WirePro Analysis) to evaluate the sticking risks for running  wireline logging tools in the well. The analysis from pre-drill information clearly indicated the well had high risk of both cable keyseating and differential sticking, but the job could be done safely on wireline with the deployment of wireline cable standoffs (WLSO).

A total of 46 WLSO were installed along the  cable across the predetermined high risk areas for cable sticking, allowing successful wireline reservoir pressure testing and sampling in the 8.5inch section. The well had extensive sandstone formations with a typical overbalance of 1000 psi, and up to 2000 psi in severely depleted reservoirs. Formation testing operations took a total of 24 hours in open hole, with the tool stationary for up to 2 hours on some stations. There was no incidence of cable sticking recorded.

The use of WLSO has saved the customer a minimum of 24 hours rig operating time, compared to operating times for pipe convey logging or wireline fishing. The risk analysis prior to logging has enabled the customer and wireline logging company to understand the risks and plan the job for optimum safety and efficiency.

Well Trajactory and Trust:
There are numerous large sands in the lower part of the well, where there will be a high risk of differential sticking. Multiple sands in the dogleg (high thrust zone under the casing shoe) create a risk of both keyseating and differential sticking.

WLSO lift the cable away from the formation, preventing it from cutting a slot into the rock or becoming wedged (keyseated) in a pre-existing slot. The WLSO also reduce the effective contact area by 99% so that differential forces do not trap the cable against the borehole wall.