Directional Drilling

CGE 578 Drilling Engineering II

EH 223

Dr. Zhixi Chen PTRL 4017 , UNSW Arina Sauki CGE 576, UiTM

What is well planning??

There are many aspects involved in well planning, and many individuals from various companies and disciplines are involved in designing various programs for the well (mud program, casing program, drill string design, bit program, etc).

This section will concentrate on those aspects of well planning which have always been the province of directional drilling companies.

The considerations in well planning includes: Geology of the area formation tops, target zones, problem and abnormal condition zones

Formation pressure and fracture gradient

Casing program

Mud program

Cementing program

Logging program

Well control

Drillstring design

Drill bit program

Hydraulic program

Drilling vs day schedule

Drilling rig

PLANNING FOR A WELL

HOW TO DRILL A NON-VERTICAL WELL?

It is easy to drill a vertical well from the rig. But how to drill at location far away from the rig?

WELL 1

WELL 2

WELL 3

MEAN SEA LEVEL

SEABED

APPLICATIONS

Multiple wells from offshore structures

The most common application of directional drilling techniques is in offshore drilling.

Many oil and gas deposits are situated well beyond the reach of land based rigs.

Drilling a large number of vertical wells from individual platforms is both impractical and uneconomical.

The obvious approach for a large oilfield is to install a fixed platform on the seabed, from which many directional boreholes can be drilled.

APPLICATIONS

Relief Wells

Directional techniques are used to drill relief wells in order to

.

Relief wells are deviated to pass as close as possible to the uncontrolled well.

Heavy mud is pumped into the reservoir to overcome the pressure and bring the wild well under control.

9/22/2014 9:53:32 AM 7

Montara

APPLICATIONS

Sidetracking

Sidetracking out of an existing wellbore is another application of directional drilling.

This is done to bypass an

original wellbore, to explore the extent of a producing zone in a certain sector of a field, or to sidetrack a dry hole to a more promising target.

Wells are also sidetracked to access more reservoir by drilling a horizontal hole section from the existing well bore.