Page 8 - 4925

- How is the rathole drilled?

T he drill site – the location of the well – varies as the surface geography of the

earth varies. In the early days of the industry, geologists and wildcatters were able to
find oil and gas in places that were generally accessible. As people began to use more
hydrocarbons, however, the oil industry extended its search for oil and gas to all
corners of the globe. Today, companies drill wells in frozen wildernesses, remote
deserts, mosquito-ridden marshes, hot and humid jungles, high and rugged
mountains, and deep offshore waters. In short, a drill site is anywhere oil and gas
exist or may exist.
CHOOSING THE SITE

The operating company decides where to drill by considering several factors.
The most important is that the company knows or believes that hydrocarbons exist in
the rocks beneath the site. In some cases, the operator drills a well in an existing field
to increase production from it. In other cases, the operator drills a well on a site
where no one has found oil or gas before. The company often hires geologists to find
promising sites where no production exists. Geologists explore areas to try to
determine where hydrocarbons may exist. Major companies sometimes have a staff
of geologists; independents often hire consulting geologists or buy information from
a company that specializes in geological data.
Legal and economic factors are also important in the selection of a drilling site.
For example, the company must obtain the legal right to drill for and produce oil and
gas on a particular piece of land. Further, the company must have money to purchase
or lease the right to drill and produce. What's more, it must have money to pay for the
costs of drilling. The costs of obtaining a lease and drilling for oil or gas on the lease
vary considerably. Costs depend on such factors as the size of the reservoir, its depth,
and its location (offshore and remote sites cost more to drill and produce than readily
accessible land sites). A company can easily commit several million dollars to find,
drill for, and produce oil and gas. The rewards, of course, can be great, but so can the
expenses.
The operating company takes several steps before telling the drilling contractor
exactly where to place the rigand start, or spud, the hole. The company carefully
reviews and analyzes seismic records. Legal experts thoroughly examine lease terms
and agreements. They ensure that the operating company has clear title and right-of-
way to the site. Surveyors establish and verify exact boundaries and locations. The
company also confirms that it has budgeted the necessary drilling funds and that the
funds are available.
On land, operating personnel usually try to choose a spot directly over the
reservoir. With luck, the surface will be accessible and reasonably level. They also
try to pick a location that will not suffer too much damage when the contractor moves
in the rig. In an area that is especially sensitive, the operator and contractor take extra
steps to ensure that as little harm as possible occurs. Offshore, the operator hopes that
the weather is reasonably good, and, if using a bottom-supported rig, picks a spot

where the ocean bottom (the mud line) can adequately hold any rig supports in

7