This case study has a completion with 2-7/8” tubing in 5-1/2” casing without a packer, with 8 IPO gas lift valves in conventional mandrels with an orifice as the last valve and a chemical screen below that. A grooved plunger was used in this well in combination with gas lift to reduce liquid fall back losses and provides a solid sealing interface between the liquid slug and the gas below it. The liquid rate declined drastically after operating the well on the gas lift at 600 MCFD rate and 1050 psig injection pressure for eight months. The well did not recover after trying several combinations of lift gas volume and plunger speed. As the lift depth in gas lift system depends upon the intersection point between surface injection pressure and multiphase flowing gradient. The pressure and temperature survey with resistance temperature detector (RTD) sensor has been run till the heal of the well at a stabilized injection gas flow rate along with wellhead recorders, recording casing and tubing pressures and temperatures for the entire duration of the survey. This process will help determine the lift point by identifying the Joules-Thompson cooling effect on the temperature curve. And it will also help sense the maximum and minimum pressures if the well is heading (surging or slugging) by keeping the wireline gauges at each depth for sufficient time. The methodical approach of creating a bridge between gas lift design and pressure-temperature survey interpretation gives operational insights into what was wrong with the gas lift operating envelope. The injection pressure endpoints are generated after performing a well-delivery analysis simulation with lower bottom hole pressure (revealed from the survey). And by utilizing Winkler’s gas passage analysis, the gas rate through designed port sizes in gas lift valves can be simulated, which is required for the existing deliverability of the well. Recent changes in operating conditions were proposed after performing several simulations on downhole flowing pressure and temperature at changing injection rates to measure the decrease in production. And applying these new conditions backed by the well’s data brought the well’s production back on the curve. This case history shows the complete scheme of creating an effective lift gas troubleshooting matrix in gas lift systems from concept initiation to execution and field installation.
The Downstroke Pump and Special or Unusual Sucker Rod Pumps Explained This paper will explain the author’s theory of operation of the pump that lifts fluid on the downstroke, using the weight of the rods, and its loading of the sucker rod string and pumping unit. Other special sucker rod pumps will be likewise explained, using the author’s understanding, including the family of double displacement type pumps, compound compression ratio pumps, traveling barrel pumps, and others. Also discussed will be the loading changes incurred when some of these pumps are configured in the top hold down, bottom hold down or tubing pump configurations.
With today’s highly dynamic unconventional wells, gas separation is essential after the conversion from electric submersible pumps (ESPs) to rod lift. Unconventional wells in the Permian Basin have high initial rates with steep declines rates, which result in a high gas-to-liquid ratio very early in the life of the well. As the reservoir pressure draws down below bubble point pressure, increasing volumes of free gas begin to break out of solution. This results in downtime due to erroneous attribution of well condition to pumped off in a critical time when aggressive fluid extraction is needed. Better well optimization is achievable through proper gas separation to maximize production and minimize downtime. Common solutions to this problem involve the use of Mother-Hubbard or packer style separator, which are not always adequate for the task and can be easily overrun by gas. Additionally, if the well is pumped too aggressively, the gas separators can be overrun by production, meaning minimal gas separation occurs. Combining the efficiency of the industry’s leading packer style gas separator, a patented shroud and the new innovative technology of the bypass tubes from the ESP Gas ByPass, the Silver Bullet maximizes gas separation using two pathways for gas separation to occur. Using the Silver Bullet increases total production by both ensuring that the pump is full and by reducing the amount of time the well spends idle. Furthermore, decreasing the number of gas interference events helps reduce failure and increase the life of downhole equipment. Less gas interference in the pump leads to longer run times, more consistent pump fillage and ultimately more revenue. This paper details the technology behind the Silver Bullet and presents case studies proving tool efficiency.
Shooting fluid levels has become a well-known practice in support of daily production operations. The practice of shooting fluid levels is so well-known, in fact, that the term, “shooting fluid levels” is assumed to mean checking the fluid level to determine if a well is producing the maximum fluid potentially available from the formation. The most common use of an acoustic liquid level instrument is to measure the distance to the liquid level in the casing annulus of a well having a downhole pump. Shooting fluid levels inside the tubing (instead of just inside the casing annulus) is common practice in flowing gas wells. Fluid level both inside the tubing and inside the casing annulus is a valuable trouble-shooting technique used on wells that have either stopped producing altogether, or production rate has drastically decreased. Analysis of acquired fluid level shots can determine if there is a hole in the tubing. Tubing shots acquired at uniform time intervals can show ineffective pump operation, where down hole liquid level rise in the tubing occurs too slowly. Fluid levels shots are effective tools when troubleshooting oil and gas wells. Many fluid level examples will be presented that discuss how tubing and casing shots are acquired and analyzed to determine hole-in-tubing on all types of oil and gas wells.
Sucker rod pumping is largely regarded as the final artificial lift method in a well’s lifecycle. Until now, the industry standard application of sucker rod pumping systems has been up to 400 barrels per day fluid production. With the industry advancing towards deeper wells and increasingly aggressive production targets, the challenge of meeting these application parameters while decreasing costs has become forefront to an operator’s requirements for profitability and in some cases, survival. To meet this need, Lufkin has established a system design comprised of a novel conventional 2560-500-320 pumping unit and fit-for-purpose rod string and pump, coupled with the ability to accurately control performance with automation. Through a comprehensive design analysis which factors in well characteristics, operational preferences, and production requirements, a system was developed to optimize production while minimizing lifting costs for operators. This approach has proven to lower or eliminate capital and operating costs for oil and gas producers by reducing the number or types of artificial lift methods, increasing fluid production, reducing failures, and lowering workover costs, as compared to other artificial lift methods or different pumping unit types. This paper will review design objectives, challenges, predictive analytics, implementation, economics, and the application results ranging from 400 to over 1000 barrels per day of fluid production achieved.
The cavitation phenomenon has been extensively studied for many years, however, guidelines on how to implement this existing knowledge to the actual operation of the jet pumping systems in the oilfield are not abundant and, as per the author can see it, not yet being presented in such way that the people that operate these systems in the oilfield could implement on a straight forward way. It has been proven that using a scientific and easy to follow methodology, it is possible to prevent jet pump operating problems related to cavitation, during the early, middle and late stage of the well production life. Preventative and Corrective methodologies are based on: Measured production rates, power fluid rate and pressure, gas to liquid ratio, jet pump seating depth and jet pump nozzle/throat combination.
This paper presents a straight forward discussion on the jet pump cavitation, its hydrodynamics, causes, identification, potential damage, consequences on the jet pump performance and methods to predict it and avoid it.
Understanding rod loading is vital to reducing failure rates in reciprocating rod lift systems. By changing the minimum stress and using the modified stress analysis instead of the modified goodman diagram, manufacturers are “tricking” you into using high tensile strength and/or premium sucker rods in your rod designs. This presentation will attempt to explain rod loading why most rod lift applications do not require or need high strength and/or premium sucker rods.
The ESP system is a mechanical/electrical/hydrodynamic system. It is costly when it fails as the tubing has to be pulled and much or all of the equipment is replaced.
This paper points out tips in the below various areas that if considered are likely to increase the average run life of ESP Systems
-Failure definitions from data
-Tips for running in Harsh Conditions
-RCFA and follow up
The information summarized includes industry findings and experience from the author’s backgrounds
The capability of a gas lift system is heavily dependent upon the available gas lift injection pressure. Gas lifting a well from the deepest point of the formation results in higher drawdown pressure, more production with less lift gas, and less gas lift equipment yielding a more efficient system. However this cannot always be achieved because of limited injection pressure, limited gas injection rate and/or limitations of the gas lift equipment. In a gas lift project, what size compressor is needed to deliver the desired production? If a compressor is already in place, how deep can gas be injected and will it achieve the desired production? To answer these questions, an Equilibrium Curve can be developed. NODAL analysis and production information are necessary to build an Equilibrium Curve for a well. The outcome of this process is a plot of liquid production rate at various gas injection depths. This will provide the necessary information to size the compression needed to achieve the target liquid production rate and to determine the gas lift mandrel and valve design. Couple this curve with additional analysis will result in liquid production rates at various gas lift injection rates. Injection rate and pressure can then be used to determine compression horsepower required. The most efficient operation will be the gas injection pressure that yields the lowest compressor horsepower per barrel of liquid produced.
In some of today’s unconventional wells, sucker rod pumping systems are facing challenges related to excessive wear, affecting production and increasing operational costs. One of the reoccurring damages in a sucker rod pumped well occurs near the kick-off point in a deviated well between the coupling and the tubing or between the sucker rod and the tubing; the metal-to-metal contact causes hole-in-tubing failures and operators have been seeking solutions to mitigate or minimize excessive tubing wear in highly deviated wells. Wear caused by both metal contact and abrasive particles, as well as corrosive attack from the wellbore’s fluid also affects the metal integrity of the tubing, coupling and sucker rod. It is beneficial to develop fundamental understanding on wear and friction concepts in rod lift applications, to optimize rod lift product designs and improve Mean Time Between Failures (MTBF) in deviated wells.
In this paper, the concepts of friction and wear will be explained from applied rod lift engineering perspective. Field tested solutions to reduce tubing wear will be presented with lab and field data.
Today, a good upstream or production engineer must understand the running condition of every well of which he is in charge in order to optimize production & profitability, usually by adjusting various setpoints. Typically, he will use data recorded by a pump-off controller (POC), fluid level shots, etc. as well as often coupling this wellhead-level data with intermittent information from stock tanks or test batteries.
To make things more complicated, most of the data generated by sensors on a field stays on the field controller’s local memory with just a select few data points actually transmitted (via low-bandwidth SCADA) to a host server and made readily accessible to engineers. Typically, this system is just capable enough to allow an engineer to diagnose crude issues and major failures. More modern systems send data to centralized control rooms far from the field, almost always unstandardized and unsanitized – as a result, more data sent means more man-hours needed to actually parse and analyze it which often falls by the wayside. In addition, it is often impractical to fully instrument a field with traditional automation solutions given the overwhelming infrastructure required and installation burden. As a consequence, most operators rely on incomplete data, leading to significant inefficiencies along with high operating costs.
In this presentation, we introduce state-of-the-art developments, both in terms of hardware technologies and mathematical data processing techniques used to automatically interpret data, as well as how these developments effectively leverage data points across the field to (1) reduce the cost of monitoring assets by an order of magnitude, making it affordable for lower flow legacy wells, (2) remove the need for routine in-person inspection of leases, and (3) increase production and equipment life-time while reducing power consumption through optimization.
Vulnerability of remote monitoring and control systems in the Oil and Gas industries By George Tyson and David Allen, Oiltek Systems LLC The Modern oil and gas industry extensively uses systems to remotely monitor and control operations throughout the process. Supervisory control and data acquisition (SCADA) systems have had wide acceptance and used for years. Many SCADA systems use the Modbus protocol, developed in 1979, to communicate between the parts of the system. Most of these systems operate under MS Windows or DOS. This creates an environment of ever expanding vulnerabilities. Hackers have used these vulnerabilities to wipe out revenue and destroy infrastructure. In 2021 Colonial Pipeline Co. had their major East Coast pipeline shut down by hackers. Hackers also broke into the water system of Florida City and tried to pump in a "dangerous" amount of a chemical and was only stopped by an alert employee. In a similar incident, in 2015 hackers were able to flick digital switches in Ukrainian power substations, causing cuts affecting hundreds of thousands of people. These vulnerabilities are growing. Every time MS Windows is updated there is a chance of a new vulnerability to be introduced into the operating system or in third party software. The new system that is entering service in the industry is the Internet of Things (IoT) or the Industrial Internet of Things (IIOT). The very nature of these systems allow them to be secured far better than SCADA and other legacy systems. This paper will examine the structure of IoT and IIoT to show how it contributes itself to security.
Mechanical rod rotators have been used as part of the beam lift artificial lift system since the concept was first patented in the late 1930’s. By rotating the rods, the frictional wear surface can be distributed around the circumference of the rod, versus on a single side of the rod. By distributing the wear surface, the rod life will be significantly extended. In the same way, the industry has used tubing rotators to derive this same benefit on the tubing, distributing the wear around the inner circumference of the tubing. One of the biggest challenges associated with operating rotators is being able to confirm that proper rotation of the rods is taking place. The speed of rotation is very slow and is not easily observable without carefully watching the rods for several strokes, and often requires an observer to be very close to the rod string. Because of this challenge, the failure of a rotator can go undetected for long periods of time, which often results in premature failure of the rod system. This paper will explore some of the methods that have been used to monitor rod rotators, including some of the advantages and disadvantages of these methods. It will also introduce a new wireless sensor that is capable of remotely reporting not only the proper operation of a rotator, but also the actual speed of rotation, which is very useful to understand the rotator’s performance and to detect progressive failure. Field trial data was gathered as the algorithms were improved to eventually yield accurate monitoring capabilities. This data will be presented, along with several conclusions. This innovative sensor is adaptable to existing rotators, and can be easily integrated into existing pump-off controllers, so it is agnostic with respect to the manufacturer of the equipment and will have broad application for rod pump wells in the industry.