The Fastest Way to the Bottom: Straighthole Drilling Device - Drilling Concept, Design Considerations and Field Experience

Abstract

A straight top hole section in many cases is a strict requirement to be able to drill deeper sections with complex well trajectories. Especially when geological parameters tend to deviate the course, and if the hole stability is a risk, drilling of a straight surface portion of hole is a must. Conventionally, this will be achieved with steerable motors, and changing between sliding and rotary mode. The Straighthole Drilling Device, SDD, has been developed as a fully automated instrumented downhole motor with integral expandable ribs. Through permanent steering, a vertical well path is generated without any supervision required fkom the surface operator. This concept had first been deployed on a more developmental basis in the KTB ultra deep scientific wellbore in Germany, thereby exceeding the 9,000 meter target. Today, the basic technology has been converted into a highly durable drilling tool for commercial oil wells. After a description of technical concept, details and performance features of SDD, the paper will focus AGIPís drilling experiences from critical fields in southern Italy.