Smarter clocks automate multiple well plunger lift

Aug. 21, 2006
The world’s first smart, wireless, multiwell, plunger controller with the capability of allocating natural gas and oil volumes while providing real-time well tests provided a means for optimizing production from wells in the Wattenberg gas field in Colorado.

The world’s first smart, wireless, multiwell, plunger controller with the capability of allocating natural gas and oil volumes while providing real-time well tests provided a means for optimizing production from wells in the Wattenberg gas field in Colorado.

Kerr-McGee Corp. collaborated with companies in plunger-lift control to develop the smarter plunger controller.

The single control box will monitor and optimize plunger performance and maximize production rates according to real-time variables for up to eight different wells. The plunger clock configuration allows for full automation and traditional supervisory control and data acquisitions (SCADA). These features let Kerr-McGee optimize production by controlling the time that the plunger lift operates in each well.

Kerr-McGee first tested this unit in a pilot program in the Wattenberg gas field.

Wattenberg gas field

The Wattenberg gas field, along the Colorado Front Range, historically has had wells on 40-acre spacing. More than 30,000 wells are in the field that lies in a diverse agricultural region with a rapidly increasing population. In this area, the oil and natural gas industry must coexist with the predominant surface business interests and urban expansion.

To do so, Kerr-McGee has reduced its footprint substantially by drilling multiple directional wells from well pads, doing land reclamation up to the wellhead, and consolidating surface facilities.

Wattenburg field lies in a diverse agricultural area with wellheads located among various types of crops such as in this cabbage patch (Fig. 1).
Click here to enlarge image

Figs. 1-4 illustrate the need in the area to minimize surface use and coexist with the surface interest owners. In Fig. 1, the wellhead is among a cabbage crop and in the distance is the consolidated battery that services several remote wellheads. Fig. 2 shows a proposed well location adjacent to livestock facilities. The greater Wattenberg producing area is home to more than 1.5 million hoofed animals.

Wells in Wattenburg field are also near livestock facilities (Fig. 2).
Click here to enlarge image

In Fig. 3, a workover-rig operates in the midst of Colorado’s urban expansion, while Fig. 4 shows a consolidated battery in an urban producing environment.

The Wattenburg area lies in the midst of an urban expansion that complicates workover and drilling operations (Fig. 3).
Click here to enlarge image

Kerr-McGee’s surface-facility design not only enables the peaceable coexistence with surface-owner interests but also reduces surface-facility expenditures, which is important considering the average Wattenberg well produces only 60 Mscfd and 2 bo/d.

Consolidated batteries minimize the facility footprint in an urban environment (Fig. 4).
Click here to enlarge image

Because of successful cooperative efforts, operators recently have started decreasing well spacing in Wattenberg gas field to a nominal 20 acres, provided directional well development, and continued facility consolidation.

Proper exploitation of the Wattenberg gas field requires this type of surface design; however, this design also creates operational problems for artificial lift.

Plunger lift

Kerr-McGee currently operates about 3,600 Wattenberg wells. Most are on plunger lift; therefore, increasing and optimizing oil and gas production requires improving plunger performance. Optimal plunger performance requires consistent line pressure that is an independent variable outside the control of most operators.

A traditional plunger clock is a simple intermittent device that regulates flow periods and shut-in periods according to timed cycles selected by the operator. But if a traditional plunger clock opens a well during high line pressure, the plunger may not reach the surface. This inhibits the well’s immediate production performance and results in extended downtime.

This circumstance may require the lease operator to visit the well site to return the well to production and realign the plunger parameters. This solution may be temporary because the well may experience another line-pressure spike soon afterward.

Frequent visits are time consuming and the interruptions significantly reduce production (Fig. 5). In Fig. 5, the red arrows denote line pressure spikes, while the green arrows denote the operators continued attempt to return these wells to production following a pressure spike.

Click here to enlarge image

With 3,600 wells on plunger lift in Kerr-McGee’s Wattenberg field, the pressure spikes have a major effect on operations.

Smart clocks

The industry for several years has had at its disposal smart plunger clocks. These clocks can monitor real-time variables such as line, tubing, and casing pressure, as well as flow rate.

A smart clock will adjust plunger parameters on a real-time basis, given the variables it monitors. For instance, if a smart clock observes high line pressure, it will keep the well shut in until it sees line pressure return to normal. Or, if it sees that line pressure is low, it will extend the time the well is on and reduce the time the well is off.

This device would benefit Wattenberg’s low volume, pressure sensitive, plunger-lift wells. Because of surface facility consolidation, however, Kerr-McGee could not install the device until it had modified the device.

A smart clock requires input from both the wellhead and the sales point. In the Wattenberg field, however, a wellhead may lie up to 0.5 miles away from its production unit and sales point. This distance made the installation of a smart clock impractical.

Fig. 6 illustrates a typical Kerr-McGee Wattenberg consolidated battery. While this configuration minimizes surface utilization, it produces problems for artificial lift because of the distances between wellhead and sales parameters and the multiple wells producing into each separator.

Kerr-McGee, in collaboration with companies in the plunger control industry and radio industry, began implementing a wireless solution. Advancements in short-wave radio technology enabled development of the oil and gas industry’s first wireless smart plunger clock solution.

While this was the first step in making smart-clock technology applicable in Wattenberg, this solution was not complete because of the additional operational problems associated with battery consolidation.

Click here to enlarge image

The intermittent nature of plunger production and marginal production character allows an operator to produce multiple wells into a single separator (Fig. 6). To optimize plunger performance, maximize production, and ensure proper lease and well allocation, it is essential to produce only one well through each separator at a time.

A traditional plunger clock operates solely on time intervals, making this process easily controllable by the lease operator. A smart plunger clock operates independently from time; therefore, a smart clock on a consolidated separator creates an environment where multiple wells compete for the same flow conditions. This not only inhibits production but also makes the allocation of production to wells impossible.

Therefore, Kerr-McGee, with its partners, implemented a multiwell plunger controller that could be placed at the consolidated battery and knowledgeably monitor both wells flowing into the single separator. This smarter clock not only optimizes each well according to real-time parameters, but also coordinates flow time between each wellhead so that they are no longer competing or flowing against each other.

As a result, Kerr-McGee can distribute intermittent, yet real-time optimized plunger performance for four different wells into a single separator. This enables the company to maintain best practices associated with surface conservation while at the same time, maximizing production volumes and plunger performance on a real-time basis.

Because this plunger clock monitors real-time flow parameters and the flow rate from an American Gas Association (AGA) standard flow computer, Kerr-McGee can time stamp produced volumes from each well flowing into each separator.

The plunger clock, therefore, not only monitors and optimizes flow time for each producing wellhead, but also time stamps and allocates produced gas and oil volume from the separator.

This function enables a digital conversion from the traditional pin recorders used for gas allocation and creates a digitally stored, auditable data trail. It also removes the need for collecting regular fluid ratio well tests because these new plunger clocks capture real-time produced oil during each plunger cycle.

This smarter plunger clock has full automation capabilities that include digital two-way telecommunication from anywhere in the field and anywhere in the world with a network connection (including internet) to the host SCADA system. This smart clock, therefore, not only monitors real-time parameters 24 hr/day, 7 days/week, and optimizes plunger performance accordingly, but also enables the lease operators to check and monitor production and plunger performance trends on a real-time basis from anywhere in the field.

If adverse circumstances inhibit production and correction requires human attention, the smarter plunger clock also can send an alarm to the lease operator, enabling lease operators to spend their time enhancing and servicing wells that need immediate attention.

This new technology and operational step change improves operator time by removing the operator’s need to unload plunger wells inhibited by high line pressure, hand collect data from each location, allocate each wells production on a daily basis, and perform regular well tests. The smarter plunger clock has taken on all these menial tasks that once consumed valuable operator time. This enables the lease operator to spend most of his time ensuring that each well is producing to its maximum potential.

The smarter plunger clock technology is applicable outside of the Wattenberg gas field. As a result, this technology will be the new industry standard, redefining preconceived notions associated with plunger clock control and their full capability.

Acknowledgment

The author thanks Ferguson-Beauregard, Tyler, Tex., for its work on the smarter plunger clock technology.

The author

Click here to enlarge image

Theodore A. Pagano (TPagano @kmg.com) is a production engineer specialist for Kerr-McGee Corp. in Evans, Colo. He is a professional geologist and engineer with extensive experience in the US Midcontinent and Rocky Mountain regions. Pagano holds a BS in geological sciences from the University of Notre Dame and an ME in petroleum engineering from the Colorado School of Mines.