Produced Water Treatment

INTRODUCTION

•Production of water is usually associated with the production of crude oil and natural gas

 

•The produced water may be water that exists within the petroleum reservoir as connate 

water

 or bottom water.

•Water-flooding operations, water is injected into reservoir to 

 enhance the recovery 

 

Produced and treated water quality 

•Produced water always has to be treated before it is disposed or injected into the 

reservoir.

•The purpose of the treatment is to remove enough oil from the water such that the

 remaining amount of oil is the water and the oil droplet size are appropriate for the 

disposal or injection of the water.

Produced Water Treating Technology

•Suspended Solids Removal

•Suspended Oil Removal

•Chemical Treating for Control of Bacteria

•Chemical Treating for the Control of Scale

•Corrosion Control Techniques

•Other Chemical Treatment Needs

 

Suspended Solids Removal

•suspended solids have a tendency to plug the injection formation thereby tending to

 cause the produced water injection pressure to increase and the produced water 

injection flow rate to decrease.

•Suspended solids that are present in the water will exist as distinct particles of varying 

sizes and densities dispersed throughout the water phase.  

 

•Particles that are heavier than water will tend to drop to the bottom of the pipe, 

vessel or other type of container at various rates.

•Stoke’s Law describes the vertical velocity at which a particle falls through a liquid 

phase. 

 

 Stoke’s Law  

 

 

•Where :

•Δρ  = difference in density of the dispersed particle

 and the continuous phase,

•g     =“g-force” acceleration factor,

•gc   = gravity acceleration constant,

•dp   = dispersed particle diameter, and

•μL  = viscosity of the continuous phase.

  

 

it is clear that the settling velocity can be increased by:

 

 

1. Increasing the size of the solid particles (i.e. by using chemical agents), or

2. Increasing the difference in density between the oil droplet and the water phase, or

3. Lowering viscosity of the water (i.e. by operating at the highest possible temperature), or

4. Increasing the “g-force” imposed on the fluid (i.e. by centrifugal motion)

 

 

 

Fishing Technology (8)

MILLING OPERATIONS

Overview

Junk mills are the surest way to eliminate junk in the hole. There are various
mills that can be used in different circumstances. For example, the insert
type of mill is best suited for milling pipe or tools anchored securely in the
well bore; however, chatter, vibration or loose junk are detrimental to the
inserts.

صورة 15

Types of Mills

1- Insert Type

Can be used for:
• pipe/tools anchored securely in the wellbore.
Caution: Chatter, vibration, or loose junk are detrimental to the
inserts.

2- Crushed Tungsten Carbide Mills

Can be used for:
• almost anything, except in hard abrasive formations.

3- Skirted Flat Bottom Or Concave Type Mill 

Can be used for:
• flared or burred top of fish prior to engagement with an
overshot. Because the skirted mill is stabilized and the
fish is contained within the skirt, it cannot slip off

4- Blade Type Mill

Can be used for:
• junk or cast iron material which will break up.
Features:
• Rugged, durable construction
• Concave, convex, and flat-bottom designs available
• Dressed with tungsten carbide inserts for stationary fish
or junk
• Dressed with crushed tungsten carbide for loose fish or
junk
• Improved cooling during milling
• Increased milling efficiency

5- Pilot Mill/Diamond Point

The Pilot Mill/Diamond Point is used for milling tubing, casing,
liner hangers, liners, drill pipe, drill collars, wash pipe, or
perforated liners.
Using Pilot Mills:
• Select a pilot mill with a blade O.D. ¼ inch larger than
the O.D. of the tool joint or coupling of the fish milled.
The pilot O.D. should be the same as the drift I.D. of the
fish.
• Determine the best rotary speed and weight to run a pilot
mill for each job. Conditions may change from one pilot
milling job to the next in the same well. The change may
require different rotary speeds and weights at different times. In the absence of experience, start with a speed of
between 80 and 100 RPM’s and a tool weight of 2,000
to 6,000 lbs. Vary the speed and weight to obtain the
best results.
• If milling a liner or casing that is gun-perforated,
damaged with a spear, or collapsed, use 60 RPM’s and
2,000 lbs. of weight or less.
• A sudden drop in the milling rate while milling swaged
casing may be caused by a loose ring of steel formed at
a joint or weld, which turns with the pilot mill. Spud the
mill gently to break up the ring and position it for
milling.
• If the milling rate stops or drastically slows down in the
milling of wash pipe, casing or liner without a
noticeable increase in torque, the fish may be turning.
• If so, pull the mill, and retrieve the fish with a spear.

6- Tapered Mills

The Weatherford Standard Tapered Mill is designed for milling
through restrictions. The spiral blades and pointed nose dressed
with crushed tungsten carbide make the mill ideal for reaming
collapsed casing and liners, cleaning permanent whipstock
windows, milling through jagged or split guide shies, and
enlarging restrictions through retainers and adapters. The torque
encountered governs the tapered mill rotary speeds.
• To overcome torque challenges, do not exceed 75
RPM’s.
• Do not rotate a tapered mill resting on a fish. Enter the
fish with a rotary speed of 75 RPM’s ort less.
• Use less weight when running a tapered mill than a junk
or pilot mill. After entering the fish, increase the tool
weight to slowly to 1,000 to 2,000 lbs. Watch for any
torque increase.

7- Watermelon/String Mills

The Weatherford string mill is dressed with tungsten carbide
spiral blades tapered from top to bottom to enable reaming both
up and down in collapsed casing and liners. The lower
connection enables a stinger to be run below the tool to prevent
sidetracking. The mill can also be placed anywhere in a drill or
fishing string. The mill features crushed tungsten carbidedressed
reamer blades.
Can be used for:
• Smooth or rough OD
• Milling out collapsed areas in casing and liners
• Eliminating key seats and doglegs in open hole
• Extending whip stock windows

8- Flat Bottom Cone Buster
Mill

This flat bottom cone buster mill is dressed with crushed
tungsten carbide and is a very aggressive mill used to mill up bit
cones or other pieces of junk. The mill is sturdy enough for
light spudding on the junk to break it up into smaller pieces.
Large circulation ports improve mud circulation for cooling and
for the removal of cuttings. Field reports show these long
lasting mills are safer than using a rock bit because you can’t
lose any bit cones in the hole. Weatherford’s junk mills work
well when milling drillable packers, bridge plugs, retainers, and
cement.
Note: Important characteristics of cone buster mills include that
they can be furnished with:

•  large circulation ports which improve mud circulation for

cooling and cutting removal.

•  smooth outside diameter along with stabilizer pads designed

to be run inside casing.

9- Cement Mills

Can be used for:
• Milling cement

       

  

 

Fishing Technology (7)

Using a Boot Basket

Description

Boot Baskets are used to trap cuttings which are too large to circulate out of
the hole during drilling, milling or junk fishing operations. The boot basket
should be run as close as possible to the mill, bit or junk basket, etc.

Figure 2-4: Boot Basket

Table 2-3:
Weatherford Type P Boot Basket

Function

The boot basket design traps junk by producing a sudden decrease in
annular velocity when cuttings pass the larger OD of the boot and reach the
smaller OD of the mandrel and top connection of the basket.

Loading up the boot basket

Using a Globe Type Basket

Description

The Globe type junk basket is used to recover any type of small object that
may be in the well bore. The successful operation of the tool requires that a
core be cut from the formation. Any junk will be recovered above the core.

Figure 2-5: Globe and Boot Baskets

Use

The Globe Type Junk Basket is recommended when performing fishing
operations in soft to medium formations (with a drilling rate above 15 feet
per hour).

Types of globe baskets

Two commonly used globe type baskets are:
1- Bowen Itco/Globe basket
2- Weatherford Globe Type Junk Basket
The Bowen Itco/Globe basket consists of a top sub, barrel, and tungsten
carbide milling shoe. Inside are two manganese bronze catchers that are
free to rotate.
Specifications for the Weatherford and Bowen Itco Globe junk baskets are
listed in Table 2-4 and Table 2-5.

Table 2-4:
Weatherford
Globe Type Junk Basket Specifications

Table 2-5: Bowen Itco Globe Type Junk
Basket Specifications

Requirements for the shoe

The crown on the shoe should be about 1/8" to ¼" less than the hole size.
ould ssed with sten carbide to about 1/8" less than the
catche
The ID sh be dre tung
ID of the rs.

Running the globe basket