Offshore Applications

Offshore Pressure Transient Testing Applications

The significant cost savings is one of the primary drivers in choosing the SPIDR to test wells in an offshore environment. The cost of utilizing the SPIDR offshore is often less than 20% of the total cost to mobilize and run equipment downhole when you compare all the costs associated with running wire and pressure gauges downhole.

DRC’s typical offshore well testing consists primarily of Shelf, Multi-well fixed platforms and Single well caisson wells in shallow water.  These wells normally do not have any electronics installed downhole and the operator is left with the only option of intervention activities to capture pressure data or otherwise perform any workovers downhole.

Other factors that qualify an offshore well for Surface Well Testing with the SPIDR:

• Limited platform deck space – often times on small platforms there is no room to locate wireline skid units to run equipment downhole
  
• Scale or Salt accumulation – Cannot access the completion with downhole tools because of a physical restriction.  Tool string can become stuck.
  
• Collapsed or partially collapsed production tubing – Can’t access the completion and tool string can become stuck.
  
• Jack – up barge – required for single well caisson structures.  Can make well testing uneconomic
  
• End of Tubing to top perforations – most operators are unwilling to send wireline and gauge outside end of tubing for fear of not being able to recover it.  If a significant distance, can invalidate any advantage of running gauges downhole.
• HPHT – Ideal well situation to perform well testing from surface.  Normally a combination of high pressure, temperature and often associated with sour or corrosive gases such as CO2 and / or H2S which serve to drive prices even higher for downhole equipment because of the special alloy requirements for the wire, surface lubricator and gauges.
  
• Federal Governmental (Minerals, Management Service, MMS)  -  The USA Federal government requires that wells producing fromFederal offshore waters be tested on a regular basis.  We have worked with the MMS and can offer our customers a MMS Waiver form which states that operators may use surface testing measurement systems when the well exhibits any of the following qualities;
  
  • Well produces “dry” gas, or <10 BBLS/MMSCFD
  • Well is greater than 50 deg. Deviated
  • Well has a history of stuck or lost tools in the wellbore
  • Physical obstructions in the production tubing that would prohibit sending gauges downhole
  • Well is a satellite or monopod platform requiring a lift boat (economic)
  • Elevated bottom hole temperatures, >300 F.

Common Offshore Well Configurations

Offshore wells come in a variety of configurations.  Single well caisson structures located in inlandwater and near shore areas that can be as simple as a casing string emerging from the water with a wellhead affixed to the top, to multi-well fixed platform wells in water depths up to about 600 ft., and deepwater multi-well floating platforms in water depths of 1000’s of feet.  Also, Subsea wells are located in shallow to deep water areas of the world (see Subsea application).

Deepwater Applications for the SPIDR

We find that most deepwater wells install some type of “smart” completion and minimally some type of permanent downhole pressure measurement systems, therefore, SPIDR is typically not required for these wells unless the downhole system has failed.  In this case our WHP to BHP conversion algorithm is of use if there remains a SubSea Tree Gauge of sufficient quality to be used for Pressure Transient analysis.