DDC MWD units utilize a modular tool design to facilitate ease of transportation by land, sea or air and handling at the rig site as well. Tool OD is 1.88 inches diameter and 24 feet long with a single battery pack or 31 feet with a dual battery pack. The system is operational in a temperature range up to 175°C (347°F). The modular design also enables the use of system components in non-mag drill collars ranging from 3 ½ inch to 8 inch diameter simply by installing the appropriate OD fins or bowsprings. Tool operating mode can be changed without tripping due to down linking capability.
All DDC’s MWD systems are wireline retrievable and reinsertable, minimizing recovery time in the unlikely event of tool failure. The primary utility of this function is to recover the MWD should the string become stuck and jarring operations are required thus minimizing the risk of loss or damage. Retrieval requires a 2 inch minimum bore in the drill pipe and bottom hole assembly (BHA).
Data is transmitted from downhole and converted to useable data with a reliable and efficient decoding system on surface. Both surface and downhole systems are easily programmed to meet the needs of the directional objectives. The application software runs on the MS Windows® platform and can be easily configured to deliver a variety of operating functions and data. DDC also offers the flexibility of using qMWD™ and qBUS™ or Bench Tree Group software.
Positive mud pulse telemetry data transfer is the most widely used and reliable transmission system in the industry and provides DDC with the level of performance reliability demanded by today’s customers. Positive pulse systems have fewer moving parts which reduce the risk of tool failure and simplify system repair and maintenance.
The entire system is designed around a platform for reduced energy consumption. High performance lithium batteries provide over 200 hours of downhole service in temperatures up to 150°C (302°F). At temperatures up to 175°C (347°F) battery life will be reduced slightly to 175 hours. Battery life can be doubled by adding a second battery pack. Energy efficient hardware such as low power components, on demand sensors, down linking capability and operational setup options integrated into the MWD system minimize power consumption and maximize battery life. An electronic flow switch powers down the system when circulation stops and powers up when flow commences, extending battery life.
The rig floor display is designed to be intrinsically safe. The color graphics LCD screen is easy to read in normal rig operating conditions providing the directional driller and company man ready access to information needed to make timely decisions. A depth tracking option is available in addition to several screens for numeric and graphical analysis. Communication between the rig mounted transducers, safe area laptop and rig floor display is distributed through a safe area interface. This interface contains the necessary barriers and protection circuitry to ensure intrinsically safe operation of the system.