Article: Oil and Gas
Author: Olusola David, Ayibiowu
Edition : 013
Year : September, 2017
Published Online : By Creative Arts Solution Foundation
Oil and natural gas are formed when decaying plants and micro-organisms are trapped in layers of sediment and – over the course of millions of years – become buried deep within the earth, where underground heat and pressure turn them into useful hydrocarbons, such as oil and natural gas.
The layers of rock in which hydrocarbons are formed are called source rocks. High pressures underground tend to squeeze hydrocarbons out of source rocks into what are called reservoir rocks. These are rocks, such as sandstone, which feature pores large enough to permit fluids like oil, natural gas, and water to pass through them. Since oil and natural gas are less dense than water, they will float upward toward the surface. If nothing stops this migration, the oil and natural gas may reach daylight through what is called a surface seep.
More often, however, hydrocarbons’ path upward is blocked by a layer of impermeable rock, such as shale, or by some other geologic formation. These trap the oil and natural gas, either in an underground pocket or in a layer of reservoir rock, so that it may be recovered only by drilling a well.
The Nigeria positioned for international oil, gas dominance despite challenges
Just to mention afew, Advanced Drilling TechniquesOil and natural gas wells have traditionally been drilled vertically, at depths ranging from a few thousand feet to as deep as five miles. Today, advances in drilling technology allow oil and natural gas companies to reach more reserves while reducing environmental impact by:
reducing the surface “footprint” of drilling operations, drilling smaller holes and generating less waste creating less noise, avoiding sensitive ecosystems, and completing operations more quickly.
Here are some technologies used:
Horizontal Drilling - Horizontal drilling starts with a vertical well that turns horizontal within the reservoir rock in order to expose more open hole to the oil. These horizontal “legs” can be over a mile long; the longer the exposure length, the more oil and natural gas is drained and the faster it can flow. More oil and natural gas can be produced with fewer wells and less surface disturbance. However, the technology only can be employed in certain locations.
Multilateral Drilling - Sometimes oil and natural gas reserves are located in separate layers underground. Multilateral drilling allows producers to branch out from the main well to tap reserves at different depths. This dramatically increases production from a single well and reduces the number of wells drilled on the surface
Extended Reach Drilling - Extended Reach Drilling - Extended reach drills allow producers to reach deposits that are great distances away from the drilling rig. This can help producers tap oil and natural gas deposits under surface areas where a vertical well cannot be drilled, such as under developed or environmentally sensitive areas. Wells can now reach out over 5 miles from the surface location. Offshore, the use of extended reach drilling allows producers to reach accumulations far from offshore platforms, minimizing the number of platforms needed to produce all the oil and gas. Onshore, dozens of wells can be drilled from a single location, reducing surface impacts.
Complex Path Drilling - Complex well paths can have multiple twists and turns to try to hit multiple accumulations from a single well location. Using this technology can be more cost effective and produce less waste and surface impacts than drilling multiple wells.