WELLOG Borehole Navigation

Revised: 3-14-2011

WELLOG is introducing a new borehole navigation tool.

When boreholes are drilled, they often deviate from the intended direction. Drills cutting through

rock formations, may cut in the direction of least resistance. The result is that the hole may not be developed

or drilled in the direction that was originally intended.

PRECISION DRILLING:

Engineers may need to drill a borehole to a specified location. Directional drilling is an example. Another example

includes the requirement to drill within limitations of property lines. Core holes drilled for the purpose of sampling

rock formations at specific locations in the earth require directional information to confirm the location of the

samples.

ACCURACY:

Accurate navigation information is important.

Course information is accurate within 0.5 degrees with 0.1 degree resolution.

Pitch and Roll information is accurate to less than one degree.

NAVIGATION:

A Borehole navigation tool can measure the direction (Course) and inclination (Pitch) of a borehole. Using simple

trigonometry, it is possible to convert angles into rectangular coordinates. WELLOG has a Borehole Navigation

tool that has been designed to provide Borehole Navigation information.

Borehole Navigation illustration

Borehole Navigation Calculator

HOW DOES IT WORK?

The WELLOG borehole Navigation tool uses specialized sensors. The sensors include 3 axis MEMs Gyros, 3 axis MEMs accelerometers and 3 axis magnetometers. All of these sensors are integrated into a single sensor board and connected to a 32 bit microprocessor. The microprocessor performs navigation calculations at 50 Million Instructions Per Second using floating point math. A precision 24 bit a/d converter converts all sensor inputs.

MEMORY TOOL:

WELLOG is marketing a Borehole Navigation tool with 2 Gigabyte memory! This tool can be used without a

wireline. The memory tool stores navigation data. It has in internal clock. The navigation data is stored with a

time stamp. On the surface, the operator records depth and time. Measurements are made at certain depths and

the time of measurements is correlated with the depth. The result can be tabulated as required. In the most simple

applications, only the maximum pitch is needed. In other applications, short interval measurements are required

and a lengthy series of calculations are made to create an exact image of the deviation of a borehole.

The Memory tool can store thousands of lines (sentences) of borehole navigation data.

BOREHOLE NAVIGATION DATA:

The data is stored in readable alpha-numeric form referred to as a “NMEA sentence”.

EXAMPLE: $C124.5P10.4R34.6T25.5*33

Every line begins with “$”.

“C” stands for Course. In this case, the course is 124.5 degrees.

“P” stands for Pitch. In this case, the pitch is 10.4 degrees.

“R” stands for Roll. In this case, the roll is 34.6 degrees.

“T” stands for temperature. In this case the temperature is 25.5 degrees Celsius.

”*” designates the end of the sentence

The last two characters represent an XOR checksum of the data contained in the sentence in hexadecimal format.

AVAILABILITY:

Slim hole Memory Tools are available NOW!

Contact sales@wellog.com for more information.