I. LITERATURE REVIEW OF OFFSHORE OIL AND GAS DRILLING
25
I.3.2.
Drilling operations and well drilling sections
Three steps are essential in the process of exploiting hydrocarbon deposits:
1- Seismic research of deposits based on preliminary geological studies
Offshore exploration uses the technique of "seismic reflection" from a vessel emitting energy
through air guns that move forward driving a line of sensors called a "streamer" (Fig. 8). The
initial technique, which used two dimensions (2D) in the vertical plane, had a success rate of 3040%. With the transition to three dimensions (3D), by gridding with various transmitter-receiver
sets, we obtain a success rate of 70%, it is increasingly used because of the quality of the results
obtained, by integrating the time factor, we can analyze the evolution of the deposits during
exploitation in 4D.
2- Exploration of the deposit by drilling
After prospecting, the drilling exploration is to verify the estimated volumes of hydrocarbons
and to validate the decision to develop the field drilling. It is the only method to confirm the
presence of hydrocarbons and to define: the quality of the well effluent (gas or water saturated
oil); the permeability of the reservoir; the potential production and quantity of oil. When a
Figure 8: Offshore geophysical survey (Navjot, 2017)
25
I.3.2.
Drilling operations and well drilling sections
Three steps are essential in the process of exploiting hydrocarbon deposits:
1- Seismic research of deposits based on preliminary geological studies
Offshore exploration uses the technique of "seismic reflection" from a vessel emitting energy
through air guns that move forward driving a line of sensors called a "streamer" (Fig. 8). The
initial technique, which used two dimensions (2D) in the vertical plane, had a success rate of 3040%. With the transition to three dimensions (3D), by gridding with various transmitter-receiver
sets, we obtain a success rate of 70%, it is increasingly used because of the quality of the results
obtained, by integrating the time factor, we can analyze the evolution of the deposits during
exploitation in 4D.
2- Exploration of the deposit by drilling
After prospecting, the drilling exploration is to verify the estimated volumes of hydrocarbons
and to validate the decision to develop the field drilling. It is the only method to confirm the
presence of hydrocarbons and to define: the quality of the well effluent (gas or water saturated
oil); the permeability of the reservoir; the potential production and quantity of oil. When a
Figure 8: Offshore geophysical survey (Navjot, 2017)