Steering Response for Directional Wells in Soft Formations in Deep Water Developments

• Main Authors: Nygaard, Runar, Hartmann, Robin, Hareland, Geir, Hellvik, Svein
• Format: Text
• Language: unknown
• Published: Scholars' Mine 2008
• Subjects: Dog Leg Generation; Oil and Gas Fields; Rock Strength; Soft Overburden Sediments; Water Depths; Geology; Norwegian Sea
• Online Access: https://scholarsmine.mst.edu/geosci_geo_peteng_facwork/361; http://www.otcnet.org/2008/technical/schedule/tuesday_am.html

In the search new for oil and gas fields great water depth is explored. One of these areas with large water depth is the south Norwegian Sea where the water depths exceeds 1000 meter. One identified drilling challenge in such areas is the deep water combined with soft overburden sediments. To ensure correct penetration of the reservoir rotary steerable systems will be used to drill deviated well paths. However, the behavior of rotary steerable systems in soft formation was a concern because building in weak formations gives less steering response from the wellbore sidewall which limits the maximum dog leg generation. A method for calculating the rotary steerable systems steering response in different formations was developed by correlating the rotary steerable systems maximum response setting to the rock strength. This correlation was used to give guidelines to determine which sections were most likely to give good response when building angle. The sedimentary rock strength analysis indicated low values in the ranges of 2-8 MPa which call for careful directional planning. Attention with respect to the planning of the wellpaths maximum dog leg severity had to be integrated with the rock strength profile. The maximum dog leg severity obtainable in the overburden was estimated to be 2° to 2.5°. The first deviated wells from the field have given the anticipated steering response. This method should be applicable for other areas planning deviated wells in deep water with soft overburden.