Wellbore surveying is a critical component of any well construction project. Understanding the position of a well in 3D space allows for the wells geological objectives to be carried out while safely avoiding other wellbores.
Wellbore surveys are generally conducted using a magnetically referenced measurement while drilling tool (MWD) and taken while static, either before, after or sometimes during the connection. The drillstring is often worked to release trapped torque and time is often taken waiting for the survey to be pumped up. All of this consumes rig time and opens the wellbore up to wellbore instability issues.
The application of definitive dynamic surveys (DDS) which are static MWD quality surveys taken while drilling and updated continuously. There is no longer a need to stop and take a static survey eliminating MWD surveying related rig time, reducing drilling risks from additional pumps off time and improving TVD accuracy and directional control.
The rig time taken for surveying with and without DDS will be compared between similar wells in the field, and detailed analysis of relative tortuosity between DDS and non-DDS wells will also be conducted. Trajectory control analysis will be reviewed by looking at the difference in the number of downlinks between DDS and no DDS wells and also the deviation from the planned trajectory. An overall analysis of on bottom ROP will be made and an analysis as to the relative differences in TVD between static and DDS survey will be carried out.
This abstract will outline the rig time and operational savings from DDS, it will detail the surveying time savings, directional control improvements, TVD placement differences to static surveys and provide costs savings as a comparison to previous similar wells. This will be outlined over a number of wells, divided by sections as the wells are batch drilled and provide an insight into the benefits of DDS on a drilling campaign. Some discussion will be made as to the efficacy of the DDS surveys and how their error model has been developed.
DDS is a unique and novel way of taking surveys while drilling, providing static MWD quality without the added rig time costs but at a much higher frequency that the typical once a stand survey program. This paper outlines the cost and process savings associated with using the DDS surveys.