Perhaps the biggest misconception about natural gas drilling in the Haynesville Shale is that the rig is a permanent, or even long-term, fixture. The fact is, even though the rig comes first, and is hard to miss; its high-profile task takes only six to seven weeks to complete. During the drilling phase, work continues 24/7 to maintain the integrity of the wellbore (hole).
- A rig is on-site for about three weeks
- Work must take place 24/7 to maintain the integrity of the wellbore
Drillsites are selected based on a number of factors including the availability of land suitable for drilling; city permits; proximity to buildings, parks and other infrastructure; geologic considerations; proximity to natural gas pipelines; feasibility of installing new pipelines, if necessary; environmental impact; and the location of wetlands, floodplains, wildlife habitats and archaeological sites. The company's lease position in the area is also a consideration. Ultimately, energy companies strive to select sites that are as least-intrusive to daily life as possible.
Minor short-term disruptions may occur on-site. There can be noise, dust and traffic like any typical construction project; however, the majority of residents will experience few, if any, changes to daily life. Drilling practices are designed to have the smallest possible impact on the environment, and new pipelines pose no more danger than the common public natural gas lines that already service most neighborhoods.
The natural gas drilling process begins with padsite preparation, which typically lasts approximately two weeks, depending on the location. Next, the setup of the rig and the drilling of the natural gas well will take approximately six to seven weeks per well. Multiple wells are sometimes drilled from a single padsite. Although the rig is the most visible part of our operations, it is temporary and will be removed once drilling is completed. Once the layer of rock that holds the natural gas (pay zone) is reached, the well will be completed and prepped for production. Even with multiple-well padsites, the entire process frequently takes less than the building of a house or commercial building in the same area.
During the approximately six to seven weeks of natural gas drilling, operations run continuously 24 hours a day, seven days a week. The completion process takes approximately 14 days.
Multiple measures are in place to ensure that drilling operations are environmentally sensitive. Operators work with communities to determine truck routes and implement security measures.
As with any construction site, there will be additional truck traffic for the setting up and taking down of the equipment. After wells are completed, the company will return to monitor and maintain the site.
At some wellsites, trucks may return to remove naturally occurring water, which is separated from natural gas and stored in on-site tanks.
Once drilling is complete, storage tanks and other production equipment is installed and the wellsites are fenced for security. In many cases, Chesapeake makes additional improvements to the area surrounding the drillsite. Because of these improvements, completed wellsites are frequently more appealing than other utilitarian structures like water pump houses or electrical stations.
Chesapeake has a state-of-the-art cementing and casing program that protects the aquifers from any natural gas drilling activities. The hole is first drilled using freshwater mud, which is a mixture of freshwater and bentonite clay. As the natural gas well is drilled, the clay actually plates out on the side of the hole, forming what is called a “wall cake,” preventing any migration of wellbore fluid into the aquifer before it is cased.
Steel casing and surrounding layers of concrete are then installed as layers of protection separating the fluids inside and outside of the casing and preventing each from contacting each other. The depth at which the surface casing must extend is mandated by the Railroad Commission of Texas (RRC). In Haynesville Shale operations, the surface casing is typically set to a depth of approximately 1,800 feet, a depth well below the freshwater aquifer.
Additional strings of casing and tubing are eventually set through the aquifers to provide even greater separation between the natural gas stream and the freshwater tables. The five layers of steel casing and cement which go into the construction of a natural gas well virtually eliminate the possibility of the contamination of any freshwater zones.
The RRC also requires documentation of drinking water aquifer intervals, the design and installation of surface casing relative to those intervals, and the reporting of characteristics of the wellbore along with completion and production data. Other states have similar programs in place to protect drinking water resources.