**1. Introduction**

Drilling into deep lying subsurface formations, both onshore and offshore, is required to produce petroleum which is critical to meeting the world's energy mix. A rightly sized drilling rig suited to the operating environment with trained crew, provided by a drilling contractor, is deployed with other service contractors providing services such as drilling fluid engineering and mud logging to drill and complete the well according to the approved well plan. A multidimensional effort termed "Well control" is employed during drilling and completion operations to ensure that formation fluids are brought safely to the surface and subsequently processed to useful forms of fuel and petrochemical feedstock.

The drilling rig is equipped with a well control system which is basically consist of the Blowout Preventer (BOP) stack, the choke manifold, accumulator unit, and a diverter assembly. The BOP stack may be a surface BOP stack as is the case on all land, jack-up and platform drilling operations or a subsea BOP stack which is used for all floating drilling rigs. The BOP is used to seal the wellbore to contain a *kick* thereby shutting-in the well. A *kick* is the unintended flow of fluids from the formation into the wellbore due to the lowering of the hydrostatic pressure provided by the drilling fluid below the formation pore pressure. A typical BOP stack consists of an annular preventer on top, followed three ram-type preventers including a full-bore drilling spool to enable connection of the kill and choke lines. A typical surface BOP stack is shown in **Figure 1(a)**. The subsea stack includes additional control valves and lines to foster remote operation of the BOP within acceptable reaction times as illustrated in **Figure 1(b)**. The hydraulic power required for operating the well control equipment (preventers, automatic valves, and chokes) is provided by the accumulator unit according to its working pressure rating. The choke manifold which generally consists of a manual choke and a remote-controlled choke is used to control the backpressure on the well while circulating out a kick. The choke manifold also provides the least restricted flow possible in case the well cannot be controlled, and the formation fluids need to be flared at a safe distance from other equipment. A diverter assembly is used to divert a gas kick encountered at shallow depth in a safe direction when only a conductor casing is installed as the surrounding formation tends to be too weak to contain a shut-in kick. Generally, an annular-type preventer is installed on top of the conductor pipe beneath which a diverter line of large enough diameter to sustain unrestricted flow is run to a pit [1, 3, 4]. The position of a diverter system is shown in **Figure 1(b)**.

Loss of well control is widely recognized as a major hazard in the oil and gas industry with far-reaching consequences including loss of drilling personnel, negative environmental impact, loss of investments and damage to the companies' reputation [4]. The loss of well control is always initiated by a kick. The failure in detecting

#### **Figure 1.**

*Left picture (a): a typical surface BOP stack arrangement [1]. Right picture (b): a schematic subsea BOP configuration [2].*

#### *Advances in Well Control: Early Kick Detection and Automated Control Systems DOI: http://dx.doi.org/10.5772/intechopen.106800*

a kick or a malfunction in the well control system could result in an uncontrolled flow of formation fluids into the wellbore. This unwanted and uncontrolled flow of fluids is called a blowout [1, 4]. The Loss of well control (LOWC) is thus defined as uncontrolled flow of formation fluids such as gas, oil, water into a separate formation (underground blowout) or exposed at the surface (surface blowout). In addition to equipment failure, a blowout can also result from violation of procedures or human error. The loss of well control is not restricted to the drilling and completion phase as it can occur during work-over activities, and less frequently during production and in abandoned wells [5].

In this chapter we give an overview of essential principles pertinent to maintaining well control such as the role of well barriers and barrier activation in the event of a well control incident. We then discuss conventional kick detection methods, their limitations and early kick detection systems especially for deep offshore operations. We further discuss the adoption of early kick detection and automated well control in managed pressure drilling operations. Finally, automated well control for conventional drilling operations is presented especially the application of artificial intelligence in greatly minimizing human error and thereby increasing the safety of drilling and completion operations regardless of the working environment.
