Mitigate drilling risk through depleted zones and minimize cost when drilling mature fields.
Drilling mature fields involves numerous challenges. One that causes a significant amount of non-productive time is drilling through zones (reservoir) that have been produced and depleted to sub-normal pressures. The potential for wellbore instability and differential sticking is high, often causing stuck pipe that requires the well to be sidetracked. These problems often require additional casing points to be added to the original well plan, which can compromise attaining the desired wellbore ID or well TD in the objective reservoir. It can also add to drilling and completion costs due to high non-productive time.
A second challenge in mature fields is keeping well costs low. Often the reserves targeted by a well are far less than those in a virgin reservoir.
Enventure Expandable open-hole liners (OHL) are often planned into the base casing design to mitigate the risk. When drilling in mature fields, the risk of differential pressure is for the most part known. However, the extent may not be as well defined. Expandable OHL's are used to cover these problematic zones, providing an increased wellbore ID that allows drilling and completing with the next casing size as planned. This casing will cover up the installed OHL to maintain required wellbore pressure and collapse ratings. Planning in an OHL to isolate the differential pressure without compromising the original casing plan can minimize non-productive time.
Managing well cost is directly related to minimizing non-productive time. But the initial wellbore design can greatly influence well economics. SET® OHL's planned into an initial well design can produce a slimmed down well that still retains the original-size production tubing. This will not compromise production rates but will reduce well cost dramatically through higher ROP's and cost savings related to drilling a smaller wellbore.
Additionally, utilizing existing wellbores in mature fields by the application of OHL's and sidetracking to retain maximized ID at TD can add significant value in the development of mature assets.
The SET® Chart provides a table of all the standard sizes available or you can use the SET® Designer to configure a system based upon your parameters.
The use of Enventure’s expandable OHL technology has enabled the drilling of mature offshore and onshore wells. Some have saved Operators $50 to $100 million in well re-drilling costs. More importantly they have enabled multi-billion-dollar offshore development programs to proceed as planned, allowing hundreds of millions of boe to be recovered.
