Petroleum
Exploration Drilling – An Overview
Geologists & Geophysicists have agreed on the existence of a
“prospect”, a potential field. In order to find out if Hydrocarbons are indeed
trapped in the reservoir rock, we have to drill the prospect location.
Setting up – Installation
The best position for set up drilling equipment is determined. The
drilling conducted, sometime difficult, small diameter (20-50cm) the hole
generally down to depth 500-4000meters. Exceptionally, certain wells exceed 6000m.
The Drilling Well
The derrick is the visible part of the drilling rig. It is used to
vertically introduce the drill strings down the hole. These drill string are
made up of metallic tubes screwed end to end. They transmit rotating movement
(rotary drilling) to the drilling tool (the drill bit) and help circulate a
liquid (mud) down to the bottom of the well.
The Drillbit some are tric-cone, through the drill pipes, at the
extremity of which the drill bit rotates, a mud is injected, which the mud engineer
prepares and controls. This mud cools the drill bit and consolidates the sides
of the borehole. Moreover it avoids a gushing of oil, gas or water from the
layer being drilled, by equilibrating the pressure. Finally, the mud cleans the
bottom of the well, carries the rock fragments (cuttings) to surface.
The Geologist examines these cuttings to discover the characteristics of
the rocks being drilled and to detect eventual shows of HC. Sometime core
sample is taken. The core gives the inclination of layers, structure,
permeability, porosity, fluid, and fossil. The measurments down the hole called
logging, commonly lowering electronic tools into the well to measure the
physical parameters of formation rocks.
The well completion and Test
When HC are found (discovery), and the pressure is sufficient to allow
them come to the surface naturally and calibrated by test. The quantity
recoverd is measured, as are changes in pressure at the bottom of the well. In
this way, a little more knowledge is gained about the probable productivity of
the field.
The assessment
If the field is promising, the exploration team ends the first discovery
well and goes on to drill a second, even several others, several hundred or
thousand meters near the well. The exploration team is able to refine its
knowledge about the characteristic of the field.
The Different types of Platform offshore
The decision to stop drilling is made only when all these appraisal wells
have provided sufficient information or to envisage future production.
Youtube:
References:
- Google.com
- Youtube.com
- https://www.amazon.com/PETROLEUM-DRILLING-OVERVIEW-Andi-Anriansyah/dp/1792194684
- https://www.amazon.com/PETROLEUM-WELL-COMPLETION-OVERVIEW-1/dp/1792195575
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