HORIZONTAL DRILLING

INTRODUCTION

Horizontal drilling is a drilling process in which thewell is turned horizontally at depth. It is normallyused to extract energy from a source that itselfruns horizontally, such as a layer of shalerock. Horizontal drilling is a common way ofextracting gas from the Marcellus ShaleFormation. Since the horizontal section of a well isat great depth, it must include a vertical part aswell. Horizontal wells are drilled parallel to thereservoir bedding plane. A vertical well is drilledperpendicular to the bedding plane.

STATEMENT OF PROBLEM

Until the arrival of modern downhole motors andbetter tools to measure inclination and azimuth ofthe hole, directional drilling and horizontal drillingwas much slower than vertical drilling due to theneed to stop regularly and take time-consumingsurveys, and due to slower progress in drillingitself (lower rate of penetration). Thesedisadvantages have shrunk over time asdownhole motors became more efficient andsemi-continuous surveying became possible.

OBJECTIVE

The main objective of horizontal well drilling is

to enhance reservoir contact which enhances

well productivity, which is highly desirable for

enhanced oil recovery applications.

RISK ANALYSIS

Drag and Torque: Drag is a force restricting

the movement of the drill tools in directions

parallel to the well path. Torque is the force

resisting rotation movement.

Hole Cleaning: A particular problem is the

difficulty of removing the rock cuttings from

the horizontal section of the well.

Water Sensitive Shale: Shale layers

frequently tend to collapse with fresh water.

Directional Control: The fundamental

problem in horizontal drilling is overcoming

the force of gravity.

METHODOLOGY

Most horizontal wells begin at the surface as avertical well. Drilling progresses until the drill bit is afew hundred feet above the target rock unit. At thatpoint the pipe is pulled from the well and the hydraulicmotor is attached between the drill bit and the drillpipe.

The hydraulic is powered by the flow of drilling muddown the drill pipe. It can rotate the drill bit withoutrotating the entire length of drill pipe between the bitand the surface. This allows the bit to drill a path thatdeviates from the orientation of the drill pipe.

After the motor is installed the bit and pipe are loweredback down the well and the bit drills path that steers thewell bore from vertical to horizontal over a distance of thefew hundred feet. Once the well has been steered to theproper angle, straight- ahead drilling resumes and thewell follows the target rock unit. Keeping the well in a thinrock unit requires careful navigation. Down holeinstruments are used determine the azimuth andorientation of the drilling. This information is used to steerthe drill bit.

Horizontal drilling is expensive. When combined withhydraulic fracturing a well can cost up to three times asmuch per foot as drilling a vertical well. The extra cost isusually recovered by increased production from the well.These methods can multiply the yield of natural gas or oilfrom a well. Many profitable wells would be failureswithout these methods.

PHASE PLANNING & COST ANALYSIS

1

Vertical

Drilling

Drill Pipe

Drill Bit

Surface

Casing

Conductor

Pipe

2

Angle

Building

and

Lateral

Drilling

MWD Motor

Drill Pipe

Drill bit

Surface Casing

Conductor pipe

3

Perforatio

n

Perforating

Gun

Wire Line

4

Hydrauli

c

Fracturi

ng

Frac Plug

• Land acquisition and leasing : Rs 12,60,00,000

• Permitting : Rs 6,00,000

• Vertical drilling : Rs 3,97,80,000

• Hydraulic fracturing : Rs 7,20,00,000

• Completion : Rs 1,20,00,000

• Production to gathering : Rs 2,83,20,000

CONCLUSION

Horizontal well analysis requires engineering

judgment.

It is difficult to get unique answer.

Reserves are difficult to estimate during the

transient flow.