Directional Drilling Responsibilities

The following table lists the responsibilities for the implementation, execution, and quality control of directional drilling and surveying activities:



Quality Control…

Borehole representation

The wellpath is defined by a survey which gives the positions of the well at a number of points along the wellbore.

The position is defined with the co-ordinates in the North, East and Vertical…

Positional Uncertainty

During the drilling operations phase the positional uncertainty must be monitored, especially when drilling in hole sections which exhibit collision risk.

All borehole position calculations for well…

Declination and Grid Convergence Definition

Declination and Grid Convergence Definition

The following definition of declination and grid convergence should be adhered to:

In this example:

Declination D is positive ‘+’

Grid Convergence G is positive ‘+’

Survey Programme

1.0 Reasons for Directional Surveys

Surveys are taken to better define the position of the wellbore, generally relative to the surface location. The reasons for wanting this information include:

Survey tools and techniques

The following survey tools and techniques are recommended/ available:

  • Solid state magnetic survey tools
  • Conventional magnetic survey tools
  • Conventional gyroscopic survey tools
  • North seeking gyro…

Steerable Systems

Deviated wells are normally drilled using a steerable system which is a combination of bent sub, motor and MWD allowing both rotary drilling and sliding without tripping for directional changes.


Guidelines for Rotary Directional Drilling

All rotary BHA’s have a tendency to build and directional control is maintained by selecting a BHA which gives the desired build up rate (BUR).

Due to the strong build tendency, it is preferable to…

Surveying definitions

Definitions of various surveying terms:


A series of measurements made to determine the borehole trajectory. A survey comprises position (North, East and True Vertical Depth) and/or direction…

Survey policy

The survey accuracy requirements are dictated by the following:

1. Targets

The geological target should be as large as possible to minimize costs (directional drilling and surveying), considering the…

Survey evaluation

The quality of a survey is determined by comparing the actual measured borehole uncertainties against the theoretical uncertainties of the survey tool. Survey uncertainties can be divided into tool,…

Tie-In Data

Tie-in data shall be provided by the Operations Engineer and sent to the rig for the Drilling Supervisor after completion of quality assurance check on each multi-shot MWD survey.

The tie-in data will…

Well Plots

This article describes the data to be includd in the various well plots.

All plots, whether standard or non-standard shall include a:

‘Check/Signature’ box for the Operations Engineer and Petroleum…

Directional Drilling Planning

The Drilling Programme shall be checked by the Drilling Supervisor to ensure that all the information necessary for the preparation and commencement of directional operations has been included.


Survey Programme Example

If the maximum dogleg severity or maximum inclination is exceeded, the Drilling Supervisor must be consulted prior to taking any corrective action. An additional MMS should be taken while drilling, if…

Surveying Responsibilities

Surveying Responsibilities:

1. Drilling manager:

- anti-collision strategy is in place;
- blow-out contingency plan is available to ensure that as soon as there is a potential or actual blow-out at…

Surveying Wells with Anticipated Well Control Problems

This article describes the surveying guidelines for wells with potential well control problems.

Magnetic Single Shot / MWD

In Exploration, Appraisal or Development well hole sections, where mobile…

Surveying Wells with No Anticipated Well Control Problems

Surveying guidelines for wells with no potential well control problems.

In Exploration, Appraisal or Development wells hole sections, where mobile hydrocarbons are not present or potential well…

Best Practices for Running Recoverable Survey Instruments

Best practices for running a recoverable surveying instrument:

  • the time drillstring is set on slips shall be minimised. The pipe should be picked up on elevators as soon as possible after making…

Survey program and report

This article describes the data required for a survey program and report.

1 General well data

·well name / ·wellhead co-ordinates (North, East, TVD, latitude and longitude) / ·co-ordinate reference…