Formation Strength Tests Profiles and Definitions

Formation strength tests (FST’s - sometimes referred to as “leak-off tests” (L.O.T) or “limit tests” or “formation intake tests” (F.I.T)) measure the…

Coring Trouble Shooting Guide

When any of these symptoms arise, come out of the hole immediately as damage may occur to bit and barrel.

Check pump strokes hourly or if pressure changes to determine if the pump is a problem or…

Mud Logging General Guidelines

A fully equipped computerised mud logging unit shall be available for recording and monitoring well generated data, for all exploration wells. There is no mandatory requirement for a full Mud Logging…

Responsibilities for Evaluation Operations

This article describes the responnsibilities for planing and safety, logging, Pipe conveyed logging(PCL), coring, mud logging, FST and Cement evaluation logging.

Planning and Safety

The Drilling…

FST Procedure

This article presents Formation Strength Tests Equipment and Procedure.

Equipment Requirements

A formation strength test requires:

  • a Cement Pump with mud tank calibrated in ¼ bbl
  • calibrated gauges…

12. Well Testing - Typical production test contract

As each Production Test is specific, it is not normal for a COMPANY to have a contract in place such as the one briefly described in the next section. The norm is to enter a short-term contract…

Organisation and Responsibilities during Wireline Operations

The implementation of the wire line logging programme at the well site is carried out by specialist contractors under the supervision of the Drilling Supervisor, although these responsibilities can be…

Coring Assemblies

This article describes the mains components of the coring assemblies: coring bits, core barels and drillstring.

Coring Bits

  • Coring Contractor shall provide a range of diamond coring heads.
  • The bit…

What is petrophysics?

In petroleum exploration, the geological model is developed and then proved, disproved, or modified by drilling. The subsequent commercial decisions are based on the existence and mobility of…

Core Recovery, Handling and Packing

A pre-job safety meeting shall be held before pulling the core barrel through the rotary table to ensure that the Drilling and Service Contractors’ personnel understand the job and potential hazards…

Coring Fluids

Any special requirements for coring fluids shall be included in the Drilling Programme. The general requirements are described below:

  • The mud gradient shall exert an overbalance over the formation…

06. Well Testing - Equipment preparation

1 Introduction

It is usual to contract out Well Testing Services, including the inspection, testing, drifting of equipment in base workshops and on site.

The effort and time spent to ensure the…

Formation Evaluation - Organisation and Responsibilities

The evaluation requirements for drilling operations are identified by the Reservoir and Petroleum Engineering Department and are incorporated in the drilling programme for each well, or as a separate…

Formation strength testing

Limit or leak-off tests in development wells may be omitted if no hydrocarbon bearing and/or overpressured formations are to be penetrated. Information obtained from leak-off tests in straight holes…

Well evaluation guidelines for exploration wells

Evaluation work for an exploration well will be carried out from the Central Offices, so it is essential that the staff are kept up-to-date about what is happening in the field, and receive the data…

Evaluation Standards

The evaluation requirements for a particular well depend upon the type of well being drilled eg., development, appraisal or exploration.  The detailed requirements for each well shall be …

Radioactive Sources and Explosives

This article describe the requirements for radioactive sources and explosives (permit to work, transporation, handling and storage).

1. Radioactive Sources

Permit to Work

All operations involving the…

02. Well Testing - Production test objectives

1 General

Test objectives can vary from a single downhole sample to an extensive long duration reservoir limit test. This will form part of the well programme.

Stimulation and artificial lift are two…

Fishing Equipment Required for Wireline Logging

Fishing Equipment Required for Wireline Logging

The required equipment (Logging Contractor Fishing Kit) for both Cut and Thread and Reverse Cut and Thread methods are:

  •  Bowen overshot kit series 105 (H-131931) with a multiple choice of…

08. Well Testing - Health, safety and environment

"Health, Safety and Environment" are the aspects of activities which relate to how work is carried out rather than to what is done. They have been grouped together and must jointly be given equal…

07. Well Testing - Operational recommendations

1 Surface

1.1 Anti-pollution measures

It is possible that hydrocarbon pollution of surface waters could occur during production testing. A spill is likely to be limited as the well and production test…

09. Well Testing - Contracting strategy

The testing contract strategy is an integral part of the project execution plan. The contract strategy needs to be finalised at the earliest opportunity, i.e. the planning stage. Well testing cannot…

01. Introduction to Well Testing

01. Introduction to Well Testing

1 General

Successful production testing of exploration wells requires the choice of appropriate test string design, equipment and facilities, and strict adherence to safety measures. An integrated…

04. Well Testing - Personnel and responsibilities

1. Size of the production test crew

A minimum of rig personnel should be on board during well-testing operations. Well test personnel will complement the rig personnel some time prior to the actual…

Fishing Wireline with Radioactive Sources

If a radioactive logging tool sticks in the hole, the following guidelines must be adhered to:

  • Do not continue work the tool because this may result in accidentally breaking the weak link.
  • The…

03. Well Testing - Production test data acquisition

1 Bottom hole pressure and temperature

It should be noted that the information given in the following tables only partially shows the expected performance specification of the gauges. Company…

Mud and Data Logging

Mud and data logging comprise two distinct but complementary operations which may be combined, or alternatively mud logging may be carried out on its own.

1       General…

Mud Logging - Cutting sampling and description requirements

This article describes the main geological services: Cutting sampling and description requirements.

Cuttings Sampling

Across reservoir: every 5 ft, and non-reservoir every 20 ft.

Cutting samples shall…

DST Programme Example

1. Objective:

DST the 14,000’ sand to evaluate production potential.

2. Well Information

Water Depth: 130’
RKB to WL: 90’
RKB to ML: 220’

MW Drilled With: 17.0 ppg

Cuttings Sampling And Lithology Description

Accurate cuttings descriptions are essential for the following 3 reasons:

  • To pick out individual formation sequences as they are drilled, to establish stratigraphic position at all times, and hence…

Coring Operational Planning, Guidelines and Procedures

The requirements for coring shall be agreed with the Drilling Department. The Programme shall include the follwing:

  • the prognosed coring point (TVD - RKB or MD - RKB for deviated well)
  • the length of…

Wellsite Coring Guidelines

Practical guidelines for wellsite coring operations. Three of the key inputs to formation evaluation for effective reservoir development and management are:

  • Reservoir geological description
  • Log…

Acronyms logging tools - Baker Atlas

Acronyms for Baker Atlas logging tools.

Back-off                                              …

Wireline Logging Fishing - Reverse Cut and Thread Procedure

The Reverse Cut and Thread Method is recommended in case a logging tool containing a radioactive source is stuck and has to be fished.

After this point the procedure deviates from the Cut and Thread…

Core Handling and Evaluation

Cores are taken in order to measure accurately the reservoir parameters in hydrocarbon and water bearing formations, and for geological purposes. Whether a conventional steel/aluminium inner barrel…

10. Well Testing - HSE policy guidelines

10. Well Testing - HSE policy guidelines

It is the Company's policy to conduct their activities in such a way as to take foremost account of the health and safety of their employees and of other persons, and to give proper regard to the…

05. Well Testing - Equipment description

1 General

The majority of Well Testing carried out world-wide is in the 5000 psi WP regime. In recent years there has been a need to go deeper with resultant higher temperatures and pressures.


Free Point Indication/ Backoff (FPI/ BO)

More fatalities occur during free point indication/ backoff than during any other wire-line operation except perforating.

In Free Point Indication/ Backoff  (FPI/ BO) operations, the…

Formation Strength Tests Calculations

This article presents the following Formation Strength Tests Calculations:

- Formation Intake Gradient (FIG)

- Effective Mud Gradient (EMG)

- Maximum Allowable Annular Surface Pressure (MAASP)


13. Well Testing - Specifications for skid mounted separators

These specifications apply to the design and fabrication of skid mounted production vessels, including all associated piping, fittings and valves, etc., mounted on the skid where intended use of the…

11. Well Testing - Test String Programme Example

*1 5000 psi well testing programme
*1.1 Test objectives
1.To test the transition zone to determine the maximum water saturation at which oil will continue to be produced.
2.To determine the extent of…

Basics of Electric Wireline Logging

Electric wire-line logging may be subdivided into four distinct services:

1   Open hole logging.

2   Perforating and completion logging.

3  Production logging.

4  …

Stripping Over Electric Logging Cable

The following equipment should be available for stripping over a logging cable:

  • Loggers fishing kit (to be supplied by Logging Contractor).
  • Additional tension meter with cable tension readout for the…

Logging Cables and Weak Points

This article provides cable and weak strength for Schlumberger and Baker Atlas

Logging Cables And Weak Points - Schlumberger


Mud Logging - Parameters Monitoring

All the parameters specified in the contract scope of services shall be recorded against time and depth and continuously monitored. The following table lists the recording frequency and standard units…

Stuck Wireline Logging Tools

Stuck logging tools are one of the non-productive time incidents experienced in well operations. Before logging, the Drilling Supervisor shall verify that the hole is in good condition and the well is…

Wireline Logging - Perforation

This article discusses perforating casing with the use of wireline for:

  • carrying out remedial casing cementing, by squeezing through perforations and
  • for monitoring of (formation) pressures behind…

Coring Operations Guidelines

Coring operations guidelines. Core samples are taken in order to measure accurately the reservoir parameters in hydrocarbon and water bearing formations, and also for other geological investigation.…

Wireline Logging Guidelines - Quality Control

This articles describes the mains guidelines and quality checks to be performed for successful logging operations

1. Preparation prior to logging operations:

  • All wireline logging tools shall be…

Acronyms logging tools - Schlumberger

Bore Hole Compensated Sonic              BHC

Bridge Plug…

Wireline Logging Fishing - Cut and Thread Procedure

Prior to any fishing operations ensure that all personnel involved are aware of their duties by means of a pre-operation safety meeting.

Dressing the Tools

Take a new grapple, grapple control and…

Pipe Conveyed Logging (PCL) – Preparation and General Guidelines

Pipe conveyed logging (PCL) logging is performed when conventional wireline operations are not feasible, such as in high angle/horizontal wells.

 If there is doubt as to whether wireline logging…