Wellbore stimulation – Maximize your oil and gas production

Wellbore stimulation includes a range of procedures aimed at increasing the flow of oil or gas from a reservoir. These techniques are used when the natural permeability of the rock is insufficient or when the flow decreases over time. There are various stimulation methods, each applied depending on the type and conditions of the reservoir.

Hydraulic Fracturing (Fracking)

Hydraulic fracturing (fracking) is a multi-stage process used to extract oil and gas from hard-to-reach reservoirs. First, the wellbore is secured with steel and cement casing to create safe access to the reservoir. Then, targeted perforations are made along the wellbore into the surrounding rock. A mixture of water, chemicals, and sand is pumped into the wellbore under high pressure. The pressure generates fractures in the surrounding rock, which facilitates the flow of oil or gas. The sand keeps these fractures open, allowing hydrocarbons to flow to the surface. This technique is commonly used in dense rock formations, such as shale, to access previously unreachable resources.

At this point, fracking trucks play a crucial role. They transport the pumps and systems that inject a mixture of water, sand, and chemical additives under very high pressure (up to 600 bar) into the wellbore. This pressure generates fractures in the surrounding rock, often extending several hundred meters. The added sand keeps the fractures open, allowing the trapped oil or gas to flow to the surface via the wellbore.

Acidizing

Acidizing is a wellbore stimulation technique where acid, typically hydrochloric acid, is pumped into the wellbore to improve oil or gas flow. This is done by chemically dissolving the surrounding rock, especially limestone or dolomite, thereby increasing permeability. Matrix acidizing aims to clean clogged pore spaces, while fracture acidizing creates and expands fractures in the rock. This method is particularly useful in carbonate reservoirs.

Matrixstimulation

Matrix stimulation is a technique used to increase the permeability of a reservoir without fracturing the rock. Chemical solutions, such as acids or solvents, are injected into the wellbore under low pressure to remove deposits or blockages in the pore spaces. This improves the flow of oil or gas into the wellbore. Matrix stimulation is often applied in older fields or when production issues arise, to remove deposits like paraffin or mineral residues. This technique is less invasive than hydraulic fracturing and is particularly suitable for sandstone formations, where contamination is the main cause of production decline.

Waterflooding

Waterflooding is a secondary oil recovery technique where water is injected into the reservoir to increase pressure and displace remaining oil. This water is typically injected through injection wells at the edges of the oil field, pushing the oil toward the production wells. This method is commonly used in older fields where the natural reservoir pressure has declined.

Gas-Injection

Gas injection is a stimulation method where gases such as nitrogen, methane, or carbon dioxide (CO₂) are injected into a reservoir to increase pressure and promote oil flow. In CO₂ injection, the gas can partially dissolve the oil in the reservoir, facilitating its flow. This technique is particularly used in oil-rich formations where the natural pressure is insufficient.