Petroleum Engineering activities
Oil & Gas Reservoir
A Oil & Gas Reservoir, is a subsurface pool of hydrocarbons contained in porous or fractured rock formations. The naturally occurring hydrocarbons, such as crude oil or natural gas, are trapped by overlying rock formations with lower permeability. Reservoirs are found using hydrocarbon exploration methods. To obtain the contents of the oil and gas reservoir, it is usually necessary to drill into the Earth’s crust.
Drilling allows a connection from the Earths surface to a geological target at some point deeper in the Earth’s crust. It is normally done to extract oil and gas although other useful products such as water can also be drilled for. The hole that is drilled (called a well) is normally lined with steel and cement and acts a bit like a drinking straw, with the pressure at the end of the well pushing the oil or gas up to the surface. Drilling works closely with reservoir engineers and petrophysists to decide on the most efficient way to extract oil and gas in terms of the number of well, how they will be drilled and maximising the recovery of oil and gas from the reservoir.
A Production Platform (oil rig) is a large offshore structure with facilities to drill wells and extract and process oil and natural gas, until it can be brought to shore for refining and marketing. In many cases, the platform contains facilities to house the workforce as well. Depending on the circumstances, the platform may be fixed to the ocean floor, may consist of an artificial island, or may float.
Well Completion is the process of making a well ready for production of oil and gas after it has been drilled. This involves preparing the bottom of the drilled hole under the sea bed to the required specifications, running in the production tubing and its associated down hole tools as well as perforating and stimulating as required to ensure production.
A well is said to reach an “economic limit” when its most efficient production rate does not cover the operating expenses. When the economic limit is reached, the well becomes a liability and is abandoned. In this process, tubing is removed from the well and sections of well bore are filled with concrete/cement plug to isolate the flow path between gas and water zones from each other, as well as the surface. Completely filling the well bore with concrete is costly and unnecessary. The surface around the wellhead is then excavated, and the wellhead and casing are cut off, a cap is welded in place and then buried.
Production logging tools are run in completed wells to log the nature and behaviour of fluids in or around the borehole during production or injection. These logs are used to analyze Well performance and the productivity or injectivity of different zones, to diagnose problem wells, or to monitor results of a stimulation or completion. This discipline deals with a variety of techniques used to measure well performance.
The process of performing major maintenance or remedial treatments on an oil or gas well. In many cases, workover implies the removal and replacement of the production tubing string after the well has been killed and a workover rig has been placed on location. Through-tubing workover operations, using coiled tubing, snubbing or slickline equipment, are routinely conducted to complete treatments or well service activities that avoid a full workover where the tubing is removed. This operation saves considerable time and expense. Workovers rank among the most complex, difficult and expensive types of wellwork.
An oil well is a boring into the earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is produced along with the oil. A well that is designed to produce mainly or only gas may be termed a gas well.
The creation and life of a well can be divided up into five segments: Planning, Drilling, Completion, Production & finally Abandonment