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Environmental Remediation Drilling

Safety Guidelines

Page 95 of 132

SECTION 5 - WELL CONSTRUCTION, DEVELOPMENT, AND ABANDONMENT

5.1 - Introduction

Well construction consists of placing a well screen and casing (riser) into the open borehole. A drawing is

provided as Attachment 5.A - Simplified Well Construction Diagram. The materials of construction can

include screen and blank casing composed of polyvinyl chloride (PVC), low carbon steel, fiberglass,

stainless steel, and other more exotic materials. Annular materials such as gravel or filter pack (surrounding

the screen), fine sand seal, (above the gravel pack), bentonite pellets, (above the fine sand seal) and a

grouting material (impervious materials such as cement or high-solids bentonite grout) are placed in the

annulus between the borehole and screen or riser casing, after the screen and casing are installed. Finally a

surface completion consisting of a well pad, locking riser and protective bollards are installed to protect the

above ground portions of the well.

Well development includes the operations, performed on the constructed well, which mitigate the formation

damage caused by the drilling methods. Both chemical and physical techniques can be used during well

development operations. Chemical methods include treating the well with specialty chemicals such as

polyphosphates, acids and other specific compounds designed to increase the flow from the formation into

the well. Physical methods may include, high pressure jetting of water into the well, surging, bailing,

swabbing or even the introduction of dry ice or compressed air into the well to create a low pressure

environment inside the well screen and casing.

Well abandonment activities are performed on extraction, injection and monitor wells when the well is no

longer needed for its intended function. Wells can be abandoned by simply installing and impermeable

material (grout) inside of the well, or requirements may dictate that the entire well must be removed from

the ground (over drilling).

5.2 - Roles and Responsibilities

In most instances the consultant or owner determines the depth of the well and the precise location of the

well materials. The data are then provided to the driller who physically installs the well materials into the

borehole. Depending on the contractual arrangements, the driller or owner may purchase the well materials

and transport the materials to the actual well site. Well development criteria are also provided to the driller

by the owner or consultant. Finally, well abandonment parameters are many times determined by state and

local regulations.

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Safety 1st Advancer Betreibershandbuch Seite 95