Chemical Injection SkidsOffshore/Products
As the name implies, a Chemical Injection System is a piece of equipment designed to inject chemicals into a system at the required pressure for the system.
It may function continuously or intermittently, and it can be used in a wide range of settings for many different purposes in marine and offshore industry.
Through this kind of oil industry system, water is injected into the reservoir to increase pressure and stimulate the production. It is also used to displace or sweep the oil from the reservoir, pushing it towards water injection wells which are usually found in both onshore and offshore. Only 30% of the oil in a reservoir is extracted so the system is needed to increase that percentage and maintain the reservoir’s rate of production for a long period of time.
MOWE’s medium and high pressure chemical injection system and other wash water injection package are known in upstream or downstream oil or gas industry for its EOR, well cleaning, improving pipeline flow or oil recovery, and corrosion prevention advantages. In all of these various settings and purposes EOR is greatly enhance with higher pressure.
Components Of Chemical Injection Systems
The following list will briefly discuss each of the major components of a typical chemical injection system. Depending on their purpose and physical setting, different chemical injection systems may vary, however, most employ each of the following in some way:
Tanks – Tanks are one of the most fundamental aspects of any chemical injection system because they required to store the chemicals which need to be injected into the system. Tank size and structure may vary, but typically they will be horizontal and cylindrical. They may feature a flat, conical, or dished bottom with a flat or dished top.
Pumps – Pumps are another fundamental aspect of chemical injection systems because they provide the source for generating the flow the pressure required to achieve the system’s objective. Pumps may be of a diaphragm or plunger type and may feature a number of different power sources including electric motor, air operated motor, solar power motor, or solenoid driven motor.
Valves and instrumentation – Valves and instrumentation are needed to measure and monitor what is going on within the system. For instance they will often monitor the liquid level inside the tank, allow for the calibration of the flow rate, monitor and adjust the pressure within the system, and set off alarms and other fail safes designed to ensure safety and proper function. Specific gauges and valves may vary depending on the exact purpose of the chemical injection system and the client’s own unique set of requirements and needs.
Electrical – A chemical injection system’s electrical system provides a way for the system to be started or stopped either locally or remotely. Typically the various controls and functions will be routed to a control panel for ease of use and function.
Skid Structure – All skid mounted chemical injection systems will also of course feature a skid structure as part of their fundamental component parts. The skid structure provides the structure itself for the system and is designed in such a way to protect the system while accommodating its various parts. It will usually feature structural steel which has been continuously welded. Often it will also feature a drip pan designed to collect drained chemicals.
Advantages of Chemical Injection Systems Integrated Into Modular Process Skids
By integrating the chemical injection system into a modular process skid, customers are able to gain a number of significant advantages. For instance compared to non-skid mounted units, modular process skids are:
- - More cost effective
- - More space efficient
- - Feature greater safety
- - Can be fabricated and installed quickly
- - Ensures reduced downtime at the worksite
- - Provides greater quality assurance
- - Constructed in more controlled environments
- - Allowed to use in hazardous areas
- - Easy identification in asset management
- - Undergoes FAT & Safety test prior to delivery
Additional knowledge of Enhanced Oil Recovery (EOR)
Oil production is separated into three phases: primary, secondary and tertiary, which is also known as Enhanced Oil Recovery (EOR). Primary oil recovery is limited to hydrocarbons that naturally rise to the surface, or those that use artificial lift devices, such as pump jacks. Secondary recovery employs water and gas injection, displacing the oil and driving it to the surface. According to the US Department of Energy, utilizing these two methods of production can leave up to 75% of the oil in the well.
The way to further increase oil production is through the tertiary recovery method or EOR. Although more expensive to employ on a field, EOR can increase production from a well to up to 75% recovery.
Used in fields that exhibit heavy oil, poor permeability and irregular fault lines, EOR entails changing the actual properties of the hydrocarbons, which further distinguishes this phase of recovery from the secondary recovery method. While water flooding and gas injection during the secondary recovery method are used to push the oil through the well, EOR applies steam or gas to change the makeup of the reservoir.
Whether it is used after both primary and secondary recovery have been exhausted or at the initial stage of production, EOR restores formation pressure and enhances oil displacement in the reservoir.
There are three main types of EOR, including chemical flooding, gas injection and thermal recovery. Increasing the cost of development alongside the hydrocarbons brought to the surface, producers do not use EOR on all wells and reservoirs. The economics of the development equation must make sense. Therefore, each field must be heavily evaluated to determine which type of EOR will work best on the reservoir. This is done through reservoir characterization, screening, scoping, and reservoir modelling and simulation.
Thermal recovery introduces heat to the reservoir to reduce the viscosity of the oil. Many times, steam is applied to the reservoir, thinning the oil and enhancing its ability to flow. First applied in Venezuela in the 1960s, thermal recovery now accounts for more than 50% of applied EOR in the US.
Chemical injection EOR helps to free trapped oil within the reservoir. This method introduces long-chained molecules called polymers into the reservoir to increase the efficiency of water flooding or to boost the effectiveness of surfactants, which are cleansers that help lower surface tension that inhibits the flow of oil through the reservoir. Less than 1% of all EOR methods presently utilized in the US consist of chemical injections.
Gas injection used as a tertiary method of recovery involves injecting natural gas, nitrogen or carbon dioxide into the reservoir. The gases can either expand and push gases through the reservoir, or mix with or dissolve within the oil, decreasing viscosity and increasing flow.
Carbon dioxide EOR (CO2-EOR) is the method that is gaining the most popularity. While initial CO2-EOR developments used naturally occurring carbon dioxide deposits, technologies have been developed to inject CO2 created as by-products from industrial purposes.
First employed in the US in the early 1970s in Texas, CO2-EOR is successfully used in Texas and New Mexico and is expected to become more widely spread in the future. Nearly half of the EOR employed in the US is a form of gas injection.
Other EOR applications gaining acceptance are low-salinity water flooding, which is expected to increase production by nearly 20%, and well stimulation, which is a relatively low-cost solution because it can be employed to single wells (rather than the whole reservoir).
Offshore EOR Applications
Although EOR applications are predominantly employed onshore, technologies are being developed to expand the reach of EOR to offshore applications. Challenges that presently exist for offshore EOR include economics of the development; the weight, space and power limitations of retrofitting existing offshore facilities; and fewer wells that are more widely spaced contributing to displacement, sweep and lag time.
Currently, the application of EOR is being considered for a number of offshore developments. With successful subsea processing and secondary recovery methods employed in offshore environments through water and gas injection, the technologies to apply EOR methods is quickly nearing.