7. SAND CONTROL7. SAND CONTROLMETHODS

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LESSON OUTCOMES

• At the end of this section, the students will be able to :

• Understand sand problems.• Understand sand problems.

• Identify sand control mechanisms.

• Apply mechanical and chemical methods.

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INTRODUCTION

• Sand production is one of the oldest problems of the oilfield, usually associated with shallow formations, but insome area sand problems may be encountered to depthssome area sand problems may be encountered to depthsof 12,000 feet or more.

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• Causes of sand production are related

– Drag forces of flowing fluid

– Reduction in formation strenght often associated with waterproduction due to dissolving or dispersion of cementing materials

SAND CONTROL MECHANISMS

Reduction in formation strenght often associated with waterproduction due to dissolving or dispersion of cementing materials

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• Sand production can be controlled by three mechanisms:

1. Reducing Drag Forces – Cheapest and most effective. It often isthe natural outcome of proper well completion practices.

2. Bridging Sand Mechanically –

SAND CONTROL MECHANISMS

2. Bridging Sand Mechanically –

• Wide application

• Difficult to apply in multiple zones or small diameter casing.

3. Increasing Formation Strength

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• Mechanical methods of sand control involve use of

– Gravel to hold formation sand in place (with a screen to retainthe gravel)

– A screen to retain the fromation sand (with no gravel).

• Basic problem is how to control formation sand without an

MECHANICAL SAND CONTROL DESIGNCRITERIA

• Basic problem is how to control formation sand without anexcessive reduction in well productivity.

• Basiic design parameters include:

1. Optimum gravel size in realation to formation sand size.

2. Optimum screen slot width to retain the gravel, or if no gravel,the formation sand

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Formation Sand Size Analysis

• The first step is getting representative samples.

• A number of samples are needed. Full-diameter cores arebest and side wall cores are good.best and side wall cores are good.

• Samples from perforation, washing or back-surging areacceptable.

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Formation Sand Size Analysis

US mesh size Approximate diameter

(in.) ( microns )

40/60 0.014 350

30/50 0.018 45030/50 0.018 450

20/40 0.025 630

16/30 0.035 880

12/20 0.050 1260

8/16 0.071 1770

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Screen Slot Size and Gravel Size

Wire wrappedscreen

used for sandcontrol

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• The following rules-of-thumbs are suggested:

1. Use as large a gravel as possible, but formation sand must bestopped at the edge of the gravel pack

2. Gravel size should be six times

3. Pay more attention to the smaller sand sizes, particularly with

Screen Slot Size and Gravel Size

3. Pay more attention to the smaller sand sizes, particularly withhigher flow velocity.

4. Pack the gravel tightly.

5. Don’t mix gravel with formation sand in placement.

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GRAVEL PACKING

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PRACTICAL CONSIDERATIONS IN GRAVELPACKING

• The key to successful packing are:

1. Selecting gravel of the proper size and quality.

2. Placing the gravel without contamination, atthe proper location, as tightly as possible – thenholding it in place for the life of well.

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• Process of Gravel pack:

Enlarge the gap between the sand face and the screen by the use

of a special drill bit known as under reamer.

GRAVEL PACK TECHNIQUES

of a special drill bit known as under reamer.

This under reamer enlarges the hole when the drill string is rotated

The enlarged borehole gap is then completely filled with gravel

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Gravel Packing – Surface Operations

Potassium chloride , CaCl, NaBr brine base fluid is used to pump gravel into the

desired interval.

GRAVEL PACK TECHNIQUES

Low concentration of gravel are added continuously while pumping.

High gravel concentration are used with viscous fluids which have sufficient

viscosity to retain gravel in suspension.

Gravel slurry is then pumped into the well using a high pressure pump

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RESIN CONSOLIDATION METHOD

• Basic objective of resin sand consolidation is to increase the strengthof the formation sand around the wellbore such that sand grains arenot dislodged by the drag forces of the flowing fluids at the desiredproduction rate.

• Sand consolidation is accomplished by precipitating resin uniformlyin the sand near the wellbore.

• Resin, attached to the sand grain contacts, hardens to form aconsolidated mass.

• Formation strength is increased enough to prevent sand production.

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• Resin consolidation has inherent advantages:

– Suitable for through tubing applicaiton

– Applicable in small diameter casing

– Leaves full open wellbore

RESIN CONSOLIDATION METHOD

Leaves full open wellbore

– Suitable for multiple reservoir completions

– Can be applied readily in abnormal pressure wells

– Work well in fine sands difficult to control with gravel packing

• Basic problem is to increase the strength of the formationuniformly through the completion zone without excessivereduction in permeability.

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Best of luck for your

Exams…..17TUNIO, May' 2011,,, Courtesy AP Aung