Copyright Baker Hughes Inc. 2007All rights reserved

Optimized Well Placement Using Advanced LWD Data for Real-Time Reservoir Navigation

Well DataLocation: Central North SeaDate: February 2007Hole Size: 8½-in.Well Type: Dual leg horizontalFormation: Claystone, limestone stringers and reservoir sand

ObjectivesDrill injectite A58 trajectory @ 5.8°/100 ft DLS, kick-off a cement plug, drill drop pilot hole in the main trajectory A58z, execute an open-hole sidetrack to drill A58y completion holeAscertain connectivity with adjacent sand bodiesReal-time ECD managementControlled open-hole sidetrack operationOptimise all three well trajectories, particularly A58y

INTEQ Solution6¾-in. AutoTrak®* RCLS with CoPilot®*, Azimuthal Propagation Resistivity, TesTrak®* and MagTrak®*

Results - Answers While DrillingTesTrak formation pressure tests proved connectivity of the main reservoir to overlying sand bodies - identifying future target potentialSuccessful utilisation of Azimuthal Propagation Resistivity to navigate the reservoir and place the wellbore - delivered 1,145ft clean sand with 70ft stand-off to the OWC

Answers While Drilling: Chevron Alba Field

The graph shows the entry into the first section of sand at the heel of the well path. The calculated

dip was 28°.

Revised model for well A58Y based on tool responses. The Azimuthal Propagation Resistivity signal strength, 2MHz phase and 400kHz resistivities were used to calculate the apparent dips of entry and exit from the main sand body, as well as dips where the roof was close to the well path.

* Reg. U.S. Pat & TM Office

Technical Background

Chevron’s requirements were to penetrate a sand interval in theinjectite leg to ascertain connectivitywith adjacent reservoirs and confirmthe area as a future drilling prospect.

A high dog-leg severity (DLS) was required to intersect areas of geological interest from the optimumcasing window depth. Formation pressure tests would be acquiredbefore pulling out of hole to set a cement plug for kicking-off to drill themain trajectories A58z & A58y. Wellbore placement within thereservoir would be critical to the wellssuccess.

INTEQ proposed AutoTrak RCLS to deliver the directional drilingrequirments and advanced Formation Evaluation technology comprisingTesTrak to deliver formation pressuretests, Azimuthal PropagationResistivity to determine wellbore placement within the reservoir and MagTrak to determine additional reservoir characteristics. Additionally, CoPilot was proposed to manage welllbore condition and ECD.

Project Objectives

Drill 5.8°/100ft DLS injectite trajectoryutilising AutoTrak RCLS. Kick off a cement plug to drill a drop pilot, A58z and execute an open-hole sidetrackto drill a completion hole, A58y.

Ascertain connectivity with adjacentreservoirs, confirming the futurepotential of the area.

Optimise well placement using Advanced LWD data for real-time Reservoir Navigation.

Project Results

All 3 trajectories were successfully drilled with AutoTrak RCLS.

TesTrak acquired valuable formation pressure data to determine reservoir connectivity and future target potential in the injectite leg. Fluid gradients were obtained through the reservoir sections which indicated differential sweeping, allowing further reservoir characterisation.

Azimuthal Propagation Resistivity signal strength and boundary detection azimuth combined with 2MHz phase difference and 400kHz attenuation resistivities were used to calculate the apparent dips of entry and exit from the main sand body, as well as dips where the roof was close to the well path.

5,090ft of 7⅝-in. liner was successfully run, the longest liner runthus far from Alba North.

INTEQ – UK DistrictAnswers While Drilling