Flowmeters for the Oil and Gas Industries

Where Do Oil and Natural Gas Come from and How Are They Formed?

Both natural oil and natural gas can be extracted from a variety of geological sources. Most oil and gas fields are located within sedimentary rocks like limestone and sandstone, because these rocks have the permeability and porosity for oil and gas to move through them and accumulate. The porosity of the rocks themselves is the factor that determines the capacity of the reservoir, while the permeability determines its productivity.

ProcessMaster electromagnetic flowmeter

Drilling into a regular accumulation of oil or gas would normally result in at least a small amount immediate flow. To commence, continue or increase the follow of oil or gas and stimulate this further, water is pumped into the underground rock layers. The high pressure of the water being pumped into the rock will result in higher flow rates and increased extraction, making the well more economical and efficient. The injected water can be effectively measured using ABB’s electromagnetic flowmeters to ensure precision and accuracy.

Natural gas or oil trapped in impermeable rock is often unable to migrate to form conventional deposits. These are called ‘unconventional hydrocarbons’ and can include shale oil, coal-bed methane and shale gas. Because the rock has a very low permeability, these unconventional accumulations must be stimulated in order to begin the flow and enable the extraction process. Hydraulic fracturing is a method of achieving this.

During hydraulic fracturing, a mixture of sand and water is pumped underground, with the high pressure of the mixture creating small fissures (fractures) in the rock. The sand in the mixture holds the fissures open, thus resulting in a higher permeability and allowing the gas or oil to move more freely from the rock pores into the producing well. ABB’s electromagnetic flowmeters can also be used for precise measurement of the fracturing fluid and the blending of the additives used during this process.

Conventional accumulation

Unconventional accumulation

Preparing the Well – Drilling and Wellhead Installation

The Application

To begin with, drilling mud is used to prepare a borehole. This mud cools the drill bit and ensures that rock cuttings are carried back the surface, while at the same time stabilizing the walls of the well. Once the hole has extended beyond the deepest aquifer, the drill pipe is then removed and replaced with a steel pipe that is referred to as ‘surface casing’. Cement is then pumped through this casing and then back again, where it sets and creates the borehole wall. This solid bond prevents any fluids from migrating vertically between the casing and the hole.

Most importantly, this creates an impermeable barrier between the well bore itself and any freshwater sources which may be nearby. Finally, the drill rig is removed and a connection between the final casing and the rock containing the oil and gas is established. The well is now complete and ready for extraction.

Well

Drilling

The Challenge

When preparing the well, it is essential that the flow rate of the drilling mud (used to cool the drill bit) is precisely controlled. Measurement of the rock cuttings carried to the surface is also vital. The drilling mud entering the borehole is a mixture of sand, water and chemicals. This mixture can make flow measurement difficult due to abrasion.

To measure the drilling mud accurately, the flowmeter must be able to withstand abrasion from not only the drilling mud itself, but also potentially harsh environmental conditions such as variance in ambient temperature ranges, moisture and vibration in the drilling rig.

Drilling mud

The Solution

The ABB ProcessMaster is a reliable electromagnetic flowmeter that is specifically designed to meet the rigorous requirements of oil field production. The unit’s robust construction can help reduce both risks and process down-time.

ABB’s ProcessMaster provides a range of features including:

• Optimized and long lasting sensor lining materials that ensure resistance to abrasion and chemical corrosion.
• The unit is designed with flush mounted measuring electrodes. Unlike many other flowmeter designs, ABB’s ProcessMaster sensor has no rotating parts. This ensures that the unit requires less frequent maintenance and helps ensure a high level of process up-time.
• The unit’s sensor is potted to protect its internal components against moisture and vibration.

ProcessMaster sensor

Oil / Water Separation

The Application

When the well is completed and ready to be used, the extraction process can begin. Natural gas and oil flow up the well bore, and any water collected alongside hydrocarbons during the well’s production life is commonly referred to as ‘produced water’.

A considerable amount of this produced water is in fact the water that was originally pumped underground to increase the flow of oil. The water is separated from the oil in a separator. The volume of the water is generally consistent throughout the well’s life and can be a challenge for mechanical flowmeters with moving parts due to abrasive solids.

Oil / water separator

Separator

The Challenge

This ‘produced wellhead fluid’ is a complex mixture containing sand, gas and chemicals. In order to ensure consistent oil and gas production, reliable, continuous operation of the separator is essential.

To help ensure reliability and continuous operation, the ProcessMaster offers the following features as standard:

• Self-cleaning measuring electrodes which can reduce the impact of oil build-up.
• Approvals from IEC, ATEX and cFM which allow for installation in potentially hazardous areas.
• Multiple communications protocols enabling integration into a variety of management systems.
• A self-configuration sequence which automatically replicates all data from the sensor into the transmitter, thus removing the potential for human errors and ensuring faster, smoother start-ups.
• A user-friendly interface which allows quick and easy data entry for all process parameters. The inclusion of an “Easy Setup” menu ensures the operator is guided through the parameterization process step-by-step and without the need for intensive training.

ProcessMaster

Oil / water separator

ProcessMaster's self cleaning measuring electrodes

Produced Water – Management

The Application

Oil production can involve the use of millions of gallons of water to prepare and use a well. This water for injection has to be sourced then either piped or transported to the well site, so water management plays a key role in any well’s operation. Every drop of water used has financial implications, so the well site must be operated as economically as possible. There are a number of ways to handle produced water, as well as the usual considerations of transport and storage.

Treatment and Reuse on Site

Here, produced water is treated on site and then pumped back underground to maintain the oil flow of the well. Reusing water in this fashion helps to reduce cost and also reduces the dependency on separate fresh water sources.

Final Disposal

This method sees produced water either go into a pit, or it is stored in on-site tanks before being piped or transported by track to a disposal well site. It may also be stored in a tank and injected underground for permanent storage using a high pressure pump.

The Challenge

In order to ensure the best levels of performance and efficiency during the production process, it is vital that there is precise, ongoing measurement of the total amount of water either disposed of or consumed.

The Solution

The ProcessMaster unit is powerful enough to handle even the most demanding flow measurement applications. With a reputation for both accuracy and reliability, it will provide consistent, proven and repeatable measurements to account for the total amount of produced water with ease.

ProcessMaster display

Wellpad layout

Produced Water – Treatment

The Application

Depending on the strategy in place for managing and treating produced water, a range of the following treatment processes may be used.

Treatment of produced water commonly involves removal of large particles, oil/water separation and additional filtering before the water is pumped into storage tanks. Further treatment is then required to reduce any dissolved or suspended solids, resulting in a thickened sludge which needs to be carefully handled and managed.

Finally, the water is treated with ultrafiltration methods to remove any dispersed hydrocarbons. Use of evaporation technology can potentially deliver a distillate that meets drinking water standards of quality.

The Challenge

To efficiently manage this process, a robust flowmeter is essential. This is used to accurately measure chemicals used to reduce suspended and dissolved solids that may be present in the dissolved water.

Furthermore, filtration technology requires a flowmeter capable of measuring both forward flow while processing the water and also reverse flow while cleaning the filters. Another notable challenge exists where low conductivity can prove problematic for some electromagnetic flowmeters, depending on the type of filtration technique in use.

The Solution

The ProcessMaster’s advanced signal processing can handle low conductivity filtering technologies with ease. The unit provides high-end measurement performance coupled with long-term stability, and a fully configurable common electronics platform can provide tailor-made solutions whether an integral, remote or pipe mounted installation is needed.

The flowmeter provides features such as:

• Small outer dimensions, making the unit suitable for integration in skids.
• Both forward and reverse flow measurement as standard.
• Parts can protrude into the pipe system with no additional drop in pressure.
• Double-sealed measuring electrodes help minimize the risk of leakage.
• Optimized linings ensure that the measuring electrodes are resistant to chemicals.

Wellpad layout

ProcessMaster with remote and integral mount design

Produced Water – Final Disposal / Wellhead Injection

The Application

Any final disposal of produced water must be in line with environmental regulations. The water is sent into the pit or stored in on-site tanks before being either piped or carried by truck to the disposal site. It may also be stored in a tank and later injected underground using high pressure pumps, allowing it to be stored permanently.

The Challenge

The flowmeter sensor must be able to withstand the high pressure that is produced as a result of pumping produced water underground. As it is installed on the suction side of the pumps, the sensor must be able to withstand variations in pressure which at times can even include a vacuum. As space is at a premium here, as most of the measurement is done via a provided skid.

The Solution

A compact version of the ProcessMaster unit is available, with both sensor and transmitter mounted as a single entity to allow integration in a skid. The flanged sensor design covers pressure ratings as high as ANSI Class 2,500 and a wafer sensor is also available which can handle pressures up to ANSI Class 300. The system is easy to set up, and installation is simplified via a sensor memory which eliminates configuration errors and saves both time and money.

Water Transportation

The Application

In order to be injected into the well, water must first be sourced, transported or piped to the well site. Produced water either goes into the pit or is stored in tanks on-site before being transported to the disposal well site by truck or pipeline.

The Challenge

Transporting water by truck is a costly process, and as such it makes economic sense to ensure that exactly the right amount of water is transported. In order to manage this operation, a reliable and accurate flow measurement device is essential.

The ProcessMaster from ABB consistently delivers reliable and accurate measurements. When this unit is integrated with a suitable asset management system, the instrument plays a key role in maximizing operation and ensuring efficiency.

Standard features of the ProcessMaster include:

• No rotating parts protruding into the pipe, resulting in less maintenance when compared to other flowmetering technologies.
• A user-friendly, easy to operate interface which allows data to be entered quickly and easily for all process parameters.
• A robust design that can withstand even the harshest environmental conditions.

Wellhead injection

ProcessMaster wafer style and flange sensor

This information has been sourced, reviewed and adapted from materials provided by ABB Measurement & Analytics.

For more information on this source, please visit ABB Measurement & Analytics.