Advancements in Drilling Technologies – Part I
Recent advances in technologies used for oil well drilling have enabled the energy industry to access new sources of oil and natural gas to meet rising demand around the world. These new technologies have also helped reduce the environmental impact of energy production by allowing more oil and gas to be produced with fewer wells. Advances in technologies play an important role in meeting global energy demand because they enable the discovery of new resources, access to harsh or remote locations and the development of oil and gas reservoirs which were previously not economically viable. This is the first part of a two-part blog which discusses these technological advancements in oil drilling.
Horizontal Drilling
Horizontal drilling is a directional drilling process aimed to target oil or gas reservoir intersecting it at the “entry point” with a near-horizontal inclination, and remaining within the reservoir until the desired bottom hole location is reached. While the construction of a directional well often costs much more than a conventional well, initial production is greater of a conventional well. Horizontal drilling provides more contact to a reservoir formation than a vertical well and allows more hydrocarbons to be produced from a given wellbore. For example, six to eight horizontal wells drilled from one location, or well pad, can access the same reservoir volume as 16 vertical wells.
Using multi-well pads via steel fabrication can significantly reduce the overall number of well pads, access roads, pipeline routes and production facilities, minimizing habitat disturbance, impact to the public and overall environmental footprint. Horizontal wells are usually drilled to enhance oil production and in some situations the improvement may be dramatic – enabling development of a reservoir which would otherwise have been considered uneconomic. There are many kinds of reservoir where the potential benefits of horizontal drilling are evident:
- In conventional reservoirs
- Thin reservoirs; Reservoirs with natural vertical fractures; Reservoirs where water (and gas) coning will develop; thin layered reservoirs; heterogeneous reservoirs;
- In unconventional reservoirs
- Shale gas/oil, tight gas/oil, CBM, heavy oil, oil sands, etc.
Multilateral Drilling
At times oil and natural gas reserves are located in separate layers underground and multilateral drilling allows producers to branch out from the main well to tap reserves at different depths. This increases production from a single well and reduces the number of wells drilled on the surface. A multilateral well is a single well with one or more wellbore branches radiating from the main borehole. It may be an exploration well, an infill development well or a reentry into an existing well.
These wells generally represent two basic types: vertically staggered laterals and horizontally spread laterals in fan, spine-and-rib or dual-opposing T shapes. A successful multilateral well that replaces several vertical wellbores can reduce overall drilling and completion costs, increase production and provide more efficient drainage of a reservoir. Furthermore, multilaterals can make reservoir management more efficient and help increase recoverable reserves. In shallow or depleted reservoirs, branched horizontal wellbores are often most efficient, whereas in layered reservoirs, vertically stacked drain holes are usually best.
Closing Comments
As observed, horizontal and multilateral drilling techniques offer more advantages in certain cases than conventional well development. Increased efficiency and greater productivity are some of the benefits while also minimizing the environmental impact in case of horizontal drilling. However, there are other new drilling techniques which are likely to add value to drilling operations in the near future. Those will be discussed in the second part of this blog!