Well Integrity

WELL INTEGRITY Shell designs and tests the integrity of our natural gas wells to meet strict specifications based on our global drilling standards as well as the local geology and environments in which we operate. We select our well locations carefully, and our drilling, casing and cementing procedures meet or exceed regulatory requirements. They are also designed to isolate gas and any fluids in the well and protect groundwater.

WELL DIAGRAM The upper portions of our wells are specifically designed to prevent gas or fluids inside the well from contacting the drinking water in the shallow rock. Wells are made of a AQUIFER

series of steel pipes sealed in place with cement. The steel pipe protecting the drinking water extends from the surface to below the level of drinking water supplies, typically to a depth of 1,000 feet (about 300 meters) or more. The cement seal extends from the surface to the entire length of this pipe; both are tested before proceeding. Additional steel casing and cement are installed to further isolate and contain the fluids and gas in the well. We monitor pressure in the wells during and after hydraulic fracturing and throughout the life of the well to check that they are firmly sealed.

Conductor Pipe Cement Surface Casing Cement Production Casing

BREAKDOWN OF TYPICAL HYDRAULIC FRACTURING FLUIDS IMPERVIOUS ROCK

Local geologies determine the exact fracturing fluid formula; percentages may vary slightly according to location. 91% Water 8% Sand

CHEMICALS

1% Chemicals Examples of chemicals include but are not limited to:

Surfactants

Disinfectants

Scale Inhibitors

Friction Reducers

Guar

Windshield Washer Fluid

Makeup Compact

Pharmaceuticals

5,000 to 10,000 Feet 1,500 to 3,000 Meters

COMMON USES

Such chemicals may be commonly used in:

Shampoo

Household Cleaner