Workover Rig Research Articles

The Design of Self-Erection Derrick of Simple Offshore Workover Rig

Though the use of modular technology, a sub-vertical lifting offshore workover rig derrick for the marine small platform is designed, which can be installed and moved quickly. The overall derrick structure and most of the part design and selection are completed by Solidworks and Auto CAD. The static calculation for the derrick is done with the help of finite element analysis software ANSYS, and analyzed the results to ensure that the derrick designed could meet the strength requirements.

Efficient heuristics for the workover rig routing problem with a heterogeneous fleet and a finite horizon

Onshore oil fields may contain hundreds of wells that use sophisticated and complex equipments. These equipments need regular maintenance to keep the wells at maximum productivity. When the productivity of a well decreases, a specially-equipped vehicle called a workover rig must visit this well to restore its full productivity. Given a heterogeneous fleet of workover rigs and a set of wells requiring maintenance, the workover rig routing problem (WRRP) consists of finding rig routes that minimize the total production loss of the wells over a finite horizon. The wells have different loss rates, need different services, and may not be serviced within the horizon. On the other hand, the number of available workover rigs is limited, they have different initial positions, and they do not have the same equipments. This paper presents and compares four heuristics for the WRRP: an existing variable neighborhood search heuristic, a branch-price-and-cut heuristic, an adaptive large neighborhood search heuristic, and a hybrid genetic algorithm. These heuristics are tested on practical-sized instances involving up to 300 wells, 10 rigs on a 350-period horizon. Our computational results indicate that the hybrid genetic algorithm outperforms the other heuristics on average and in most cases.

FeS-Scale Cleanout With High-Pressure Coiled Tubing and Tailored Fluid

This article, written by Dennis Denney, contains highlights of paper SPE 169759, ’Extreme Challenges in FeS-Scale-Cleanout Operation Overcome Using Temporary Isolation, High-Pressure Coiled Tubing, and Tailored Fluid Systems,’ by Mustafa Buali, Noel Ginest, SPE, Jairo Leal, and Oscar Sambo, Saudi Aramco, and Alejandro Chacon and Jose Vielma, Halliburton—Boots & Coots, prepared for the 2014 SPE International Oilfield Scale Conference and Exhibition, Aberdeen, 14-15 May. The paper has not been peer reviewed. The gas-producing carbonate zones of the Ghawar field in eastern Saudi Arabia have been affected by extensive iron sulfide (FeS) scale deposition, reducing overall gas production and increasing risks during well interventions. Previous remediation attempts used workover rigs, which can be costly because of the time necessary for workovers and lost production. Hydrogen sulfide (H2S) levels (2 to 5%) in the reservoir also contribute to higher costs and risks with the use of workover rigs. H2S in the reservoir poses a safety concern with the returns at surface and a concern with potential corrosion of the coiled tubing (CT) and completion. Therefore, the safest and most economical method was deemed to be mechanical descaling with CT. Introduction Two wells were descaled mechanically by use of CT. Each well involved four major challenges: low reservoir pressure, higher reservoir temperature, horizontal openhole completion, and highspecific- gravity (3.7 to 4.3) scale. The low reservoir pressure required payzone isolation to enable circulating out the heavy scale and to minimize fluid losses to the formation. With a bottomhole temperature as high as 310°F, the operational envelope of temporary chemical packers in combination with lost-circulation materials (LCMs) to isolate the openhole section had to be expanded. Following mechanical descaling with CT, the final challenge was cleaning out the LCM in the horizontal open hole and bringing the well back to maximum gas production by use of pinpoint stimulation techniques. Scale Composition Many scale samples have been collected and characterized throughout the years with X-ray diffraction (XRD), X-ray fluorescence, scanning electron micrographs, and microscopic methods (thin section). Although the exact chemical composition of the scale changes from well to well and varies with depth in a given well, the scale deposits are mixtures of many compounds, usually dominated by FeS minerals including pyrrhotite, troilite, mackinawite, greigite, pyrite, and marcasite.

The Harmonic Response Analysis of Workover Rig Platorm Base on ANSYS Workbench

Normally, the workover rig platform is obtained only low order natural frequency by modal analysis. In order to understand the frequency response of structure dynamic load, we well carry out harmonic response analysis on the operation platform in this paper. On this basis, determine the modal frequency that is greatest effect on dynamic behaviour of the workover rig operation platform structural system. To extract the modal frequency as dynamic optimization goal or state variables.Finally, achieve forecast the possibility of dynamic interference between operation platform and other components.

Application of Toyota's Principles and Lean Processes to Reservoir Management: More Tools To Overload the Toolbox or a Step Change in Our Business?

SummaryAera Energy LLC was formed in 1997 to be a low-cost operator and producer in California. However, the low oil prices from 1998 to 1999 forced an examination of all operations in the office and in the field. Cutting costs, improving timekeeping, or reducing the scale of operations would not be sufficient without a step-change gain in efficiency. This step-change gain came from the use of principles and concepts developed in the automobile and construction industries. Toyota's twin pillars of just-in-time production and the ability of anyone to stop production rather than pass on defects, coupled with level-loading of work processes and reducing waste, were introduced. Toyota's principles were enhanced by the addition of “Last Planner” concepts developed for the construction industry. When both were implemented for reservoir-characterization and reservoir-development work, significant process improvements resulted. The resulting improvements are now being used throughout the company to improve quality by removing waste and reducing errors, to measure processes, and to improve cycle times.The unconventional diatomite reservoirs and oil-sand reservoirs at the giant Belridge field produce 65,000 BOPD from 5,300 producing wells and 2,100 injection wells. The many drilling, completion, and workover rigs have a constant appetite for new wells. To maintain production and cost targets, everything in the office has to run reliably and efficiently at all times, as well as support field operations.Different aspects of Toyota's principles and “Lean Manufacturing” are illustrated by use of project work for reservoir characterization, day-to-day reservoir surveillance, and the development work needed to plan and schedule new wells. The processes and projects typically have multiple customers and suppliers—internal and external. All involved, including knowledge workers (those who think for a living), need to work as a single system with a manufacturing mentality and to strive for continuous improvement. Customers of the knowledge work supplied by the geoscientists and reservoir engineers have benefited greatly from the introduction of the lean processes and the resulting smoother and more-effective workflows. In 2011, the Development Team's lean activities were recognized by the Association for Manufacturing Excellence, and the team received the Manufacturing Excellence Award that recognizes “continuous improvement, best practices, creativity, and innovation.”The oil industry has a reputation of being slow to adopt new technologies and techniques. However, a Lean Manufacturing mentality introduces new ideas and ways of performing knowledge work that may change this paradigm while contributing to the bottom line with reduced cycle time and improved quality. A significant additional benefit is that geoscience and engineering professionals can spend more time doing creative work and less time fixing problems or reacting to system upsets—as they simultaneously reduce waste. However, to realize all these benefits and the step changes they provide, a thorough understanding of Toyota's principles and a Lean Manufacturing mentality are essential.

Study on Load Capacity of Anchor Piles for Oil Workover Derrick

the workover rig is always fixed by anchor piles in land oilfields. Good load capacity of anchor pile is the key factor to the guarantee of safe workover operation. The load capacity test of anchor pile is complete by connecting vibration test and method of mechanical impedance. The reduction coefficient must be used in calculating the anti-pulling load capacity because of difference of soil kinds. To testify the results from mechanical impedance method, the system of pulling pile directly is built. The average error of data from this system is within 5%. It can conclude that the method of mechanical impedance and vibration test can be popularized widely to load capacity of anchor pile, especially in different kinds of soil. The research can enrich the theories of uniform section pile and give the theoretical foundation to fix the anchor piles safely during workover rig operations.

The Finite Element Analysis of Derrick Translation System in Vehicular Pressure Balance Workover Rig

Nowadays the workover rig is more often used in outdoor work, and the field environment is complicated and changeable.Therefore, it becomes extremely important to conduct a detailed analysis of stress of the workover rig derrick translational system.This paper takes Liaohe Oilfield new vehicular pressure balance workover rig derrick translation system as an example, a finite element analysis model is established to analyze the stress conditions of the derrick truck system.The result completely conforms to the actual requirements, thus verifying the rationality of the design and providing the basis for the optimization design of the translation system.

Feasibility Design of Derrick Anchor Pile Piling Position Based on ANSYS Optimization

Application of ANSYS parametric design language APDL built the model of workover rig derrick-guy line system. Take XJ70 type workover rig for example, optimization of derrick anchor pile piling position has been calculated under the condition of anchor pile ultimate uplift force. The uplift force obtained from pullout tests and different from soil type and soil condition. By optimizing calculation, on the premise of anchor pile bearing safety, the minimum and feasible piling positions have been gotten to guide piling work in special well site conditions. When the bearing capacity of soil decreased, make hook load as design variable, get the hook load limits at each pile position to ensure the ground anchor pile bearing safety.

Evaluation of operational performance of workover rigs activities in oilfields

Purpose – This paper aims to develop a practical method to evaluate operational performance of workover rigs and present an approach to measure the overall equipment effectiveness (OEE) based on results of the evaluation method.Design/methodology/approach – The area of this study focuses on workover rigs processes in the oilfield and investigates the impact of workover activities on the production at the Sarir Oilfield in Libya. The loss of time from workover procedures and electrical submersible pumps ESP installation and pulling, which affect oil well production, should be eliminated in order to reduce the cost. Several example calculations of workover operation efficiency involving actual workover operational data are presented. The method of evaluation of workover process has been developing which were the bases of OEE calculation.Findings – The measure was developed to help support continuing efforts around process improvements and cost leadership at Oilfields. The results on the empirical findings a...

Finite Element Analysis and Optimal Design for the Derrick of Workover Rig

It proposed the finite element analysis to the derrick of workover rig in the paper. The stress distributing rule of derrick has been found, based on the finite element analysis of established derrick model. It analyzed the reasons for the effects of derrick thigh stress due to the derrick sustentation disposal format, the function of doorframe structure and the producing of dangerous section. The optimal derrick structure has been made up after calculating the derrick working stress, stress state and displacement measure.

Numerical Simulation Analysis on Effects of Freezing and Thawing on Workover Rig Anchor Pile Bearing Performance

Through simulating interaction between pile and foundation soil after establishing surface-surface contact element with finite element method and ANSYS software, the load resistance performance and ultimate strength of the ground anchor pile working for a workover derrick are achieved. In winter, frozen soil depth can be up to 2 meters in north china. When temperature rises in spring, the Polar grassland changes by three stages, namely, frozen, freeze thawing and melted. But for the large temperature difference between morning and evening, the state of the soil layer is extremely unstable which greatly affect the carrying capacity of anchor piles. This paper focuses on the melting influence of soil layer and the load resistance performance is studied. With a set of calculation parameter, the simulation result shows that the carrying capacity of anchor piles decreases 28% in melted state than freeze thawing.

Structural design of an offshore hydraulic energy-storing workover rig

After more than ten years’ development, the functions of workover rigs in China can generally satisfy the demands of offshore oilfield production. For conventional workover rigs, large working space and guide rails are necessary, and they bring trouble to the workover operations. The high cost of manufacture, transportation, installation and running such general workover rigs is also an inevitable problem. Because of the advantages of the hydraulic energy-storing workover rigs, such as energy saving, environmental protection, small occupation and convenient installation, they have been widely used in onshore oilfields. In this paper, the preliminary structural design of a newly developed simple offshore workover rig will be introduced and the feasibility of applying this type of rig will be discussed.

Coiled Tubing Reduces Stimulation Cycle Time by More Than 50% in Multilayer Wells in Russia

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 154386, ’Coiled Tubing Reduces Stimulation Cycle Time by More Than 50% in Multilayer Wells in Russia,’ by A. Yudin, SPE, K. Burdin, and D. Yanchuk, SPE, Schlumberger; and A. Nikitin, SPE, I. Bataman, A. Serdyuk, N. Mogutov, and S. Sitdikov, SPE, Rosneft, prepared for the 2012 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, 27-28 March. The paper has not been peer reviewed. Traditionally, coiled tubing (CT) has had very limited service diversity in Russia. Its use has been mostly limited to wellbore cleanouts and nitrogen kickoffs after fracturing treatments. CT equipment and technologies were used to supplement stimulation operations in one of the world’s largest oil fields, Priobskoye, which has up to five separate layers per well. Conventionally, well completions at Priobskoye have involved complicated workover operations with tubing, packers, and wireline perforation after each stimulated layer. An average well with three layers took 30 days to complete. CT provided a significant improvement in completion efficiency, reducing the cycle time to just 10 to 12 days. Introduction Priobskoye is one of the world’s biggest oil fields. It is in the Khanty-Mansi autonomous region, and the Ob river divides it into two parts, the left bank and the right bank. Hydraulic fracturing is the main method used to increase production and recovery from the Priobskoye formations, and most new wells are stimulated immediately after drilling. Fracturing optimization has mostly evolved toward increasing the quality of hydraulic fractures. However, the Priobskoye field is a multilayer reservoir where separate fracturing treatments normally take excessively long times to complete. The standard completion method has consisted of a sequential approach of the workover crew perforating, the wireline crew running in tubing and packers, and the fracturing crew fracturing and pulling tubing and packers out of hole for each of the layers. That sequence takes a long time to complete the well, especially if the formation starts flowing naturally before the workover and wireline crews can manage the pressure properly to continue operations. Starting in 2008, CT fleets were employed to assist in the well-completion cycle with abrasive perforating and well-cleanout operations under pressure between the fracturing stages. The advantage of CT lies in its ability to perform the same sequence of operations significantly faster. In fact, the CT replaced both workover and wireline rigs, with the perforating performed with an abrasive material jetted through the nozzles of a special bottomhole assembly. A jet’s velocity and its focused flow create a hole inside the casing and a cavern inside the cement and the rock outside the casing (Fig. 1).

A branch-price-and-cut algorithm for the workover rig routing problem

In an onshore oil field, the productivity of oil wells decreases when they require maintenance. To restore full productivity at a well, it must be visited by a specially equipped vehicle, called a workover rig. Given a set of wells needing maintenance and a heterogeneous fleet of workover rigs, the workover rig routing problem (WRRP) consists of finding rig routes that minimize the total production loss of the wells over a finite horizon. The wells have different loss rates, require various services, and may not be serviced within the horizon due to rig availability. The rigs have initial positions and do not have the same equipment. This paper presents the first exact algorithm for the WRRP, namely, a branch-price-and-cut algorithm that relies on some of the most recent techniques introduced for the vehicle routing problem with time windows. Our computational experiments show that this exact algorithm can solve practical-sized instances in reasonable computational times.

Successful Discovery of Light Oil From an Unsuccessful Well Through Re-Entry

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 147247, ’Successful Discovery of Light Oil From an Unsuccessful Paleozoic Well Through Re-Entry - A Case Study of an HP/HT Well,’ by Haifa Al-Bader, SPE, Yousef Zaid Al-Salali, SPE, Vidya Sagar Duggirala, SPE, A. Manimaran, and S. Packirisamy, SPE, KOC, prepared for the SPE Annual Technical Conference and Exhibition, Denver, 30 October-2 November 2011. The paper has not been peer reviewed. An exploratory well, the second deepest in Kuwait, had been drilled in the Mutriba field to 22,094 ft. Two formations, Kra-Almaru and Khuff, were perforated and tested. The tests revealed the presence of sparse gas, and it was decided to test and complete this well in the Jurassic formation through re-entry. The re-entry in this ultradeep well was full of challenges; however, by overcoming all the challenges, this well was successfully perforated, stimulated, and tested, which led to the first commercial discovery of oil and gas within the Jurassic reservoir in the Mutriba field. Introduction Two zones in Paleozoic and Triassic sections were perforated and tested separately to evaluate the presence of hydrocarbon between 18,500 and 21,500 ft. The well was completed in 2004. After undesirable results were obtained from the Triassic and Paleozoic formations, exploration teams studied the feasibility of testing Jurassic formations in this well through re-entry. Testing Jurassic formations in the Mutriba field from an existing well will be more economical than drilling a new well. A snubbing unit was deployed in 2008. In 2009, a suitable workover rig was deployed to test Jurassic formations in this previously drilled well. The location of the Mutriba field is shown in Fig. 1. A snubbing unit had been used to isolate the open perforations of the Triassic zone with cement. Subsequently, a workover rig was deployed to test the prospect of a Jurassic reservoir. Testing the Jurassic reservoir behind two heavy-walled casings (7 in. 46.4 lbm/ft and 8⅝ in. 40 lbm/ft) combined with extreme sour and high-pressure/high-temperature (HP/HT) conditions warranted high health, safety, environment, and technical precautions. Challenges for re-entry to this well included HP/HT conditions, a high surface pressure, and well-killing issues. Testing of the formation fluid revealed the presence of an unexpectedly high concentration of H2S (20%) and CO2 (2%), which presented challenges for coiled-tubing (CT) operations, stimulation, flowing the well, and fluid disposal.

The Finite Element Analysis of Static Strength of Workover Derrick by Truck

Conventionally, the influence of guy wire and wind load on derrick was often ignored in the static strength analysis of derrick of truck-mounted workover rig, it does not accord with the actual working conditions. This paper made the finite element analysis for one derrick of Truck-mounted workover rig through ABAQUS software. The author derive the maximum static hock load which derrick can bear, and reasonably shorten projective radius of guy wire, under different static hock load and wind load, determining the weakest position of derrick. Truck-mounted workover rigs are widely used in the filed of workover and drilling operation, due to their characteristic of power maneuverability and convenient to use. Derrick is the mainly working part of workover rig, as well as the weak links of workover. In order to guarantee relatively high security performance, we should accurately make simulated calculation for carrying capacity of derrick in the process of designing. The author derive the maximum static hock load which derrick can bear, and reasonably shorten projective radius of guy wire, by using the ABAQUS FEM system, apply for statics analysis of derrick under different static hock load and wind load.

Models and hybrid methods for the onshore wells maintenance problem

Workover rigs are used in onshore basins but they are often in limited number and they may not attend all the maintenance requests. We consider here the problem of scheduling the rigs over a time horizon in order to minimize the total oil loss due to the idle production states. Three mixed integer linear models are proposed. The first one improves an existing scheduling-based formulation. The second one uses an open vehicle routing approach and the third one is an extended model for which a column generation strategy is developed. Several improvements are presented as well as two heuristics coupled with column generation. To our knowledge, the first optimal values for medium-size instances of the problem are presented in this paper. The results show the potential of the column generation and its interest in a practical context.

A comparison of three metaheuristics for the workover rig routing problem

The workover rig routing problem (WRRP) is a variant of the Vehicle Routing Problem with Time Windows (VRPTW) and arises in the operations of onshore oil fields. In this problem, a set of workover rigs located at different positions must service oil wells requesting maintenance as soon as possible. When a well requires maintenance, its production is reduced or stopped for safety reasons and some workover rig must service it within a given deadline. It is therefore important to service the wells in a timely fashion in order to minimize the production loss. Whereas for classical VRPTWs the objective is to minimize route length, in the WRRP the objective is to minimize the total lost production, equal to the sum of arrival times at the wells, multiplied by production loss rates. The WRRP generalizes the Delivery Man Problem with Time Windows by considering multiple open vehicle routes and multiple depots. This paper compares three metaheuristics for the WRRP: an iterated local search, a clustering search, and an Adaptive Large Neighborhood Search (ALNS). All approaches, in particular ALNS, have yielded good solutions for instances derived from a real-life setting.

A Constant Power Control System for Oilfield Electric Workover Rigs Based on Serial Communication between a PLC and a Converter

A constant power control system based on Serial communication between a programmable logical controller (PLC) and a converter is put forward for high efficiency of oilfield workover rigs and for simple operation and reliability. In the condition of different transformers’ capacity, this system makes the motor always be in constant power state automatically by selecting power limit values. Operators with different practices can make use of this system because of its manual function which meets the demand of humanized design. This system can be used in other lifting equipment whose operation mode is similar to workover rigs.

World's Deepest Through-Tubing Electrical Submersible Pumps

Summary This paper describes the development, history, and successful deployment of the world's two deepest through-tubing-conveyed electrical submersible pumps (TTCESPs). These are the first TTCESPs deployed inside of 7-in. casing. Electrical submersible pumps (ESPs) are a form of artificial lift that consists of a pump, motor, and electric cable, typically deployed by a rig and connected to electric power at surface. Their advantage is that they create greater drawdown than other forms of artificial lift, thus achieving higher production rates. However, conventional ESPs require expensive workover rigs to replace pumps, the component that fails most frequently. ConocoPhillips Alaska developed TTCESP technology to replace failed pumps rapidly and economically. In this system, a rig conventionally deploys the electric cable, motor, and seal sections with a special latching device for the pump. The pump is pulled and replaced with slickline (wireline) or coiled tubing, eliminating the requirement of a rig. The original through-tubing-conveyed (TTC) systems were developed for 7⅝-in.-cased wells. During approximately the past 10 years, it was common belief that they could not be deployed at the Milne Point field in Alaska because of the limitations of its smaller wells (7-in., 26-lbm/ft casing). This paper discusses the enabling technologies that were developed to allow running TTCESPs in 7-in. casing, including a wellhead spoolpiece and low-clearance ESP clamps. West Sak TTCESP run-time data indicate that the time between rig workovers (RWOs) will increase from 3.5 to 6 years. Pumps can be replaced for 5–10% of rig costs without the safety and environmental impacts associated with rigs. Additionally, production impacts while waiting for a rig are eliminated because slickline and coiled-tubing units are readily available on the North Slope of Alaska. TTC pumps can easily be upsized or downsized to optimize pump flow rate because of changes in production rates. This technology is of interest in areas where rig costs are high, including Arctic, remote, and offshore locations. It is also beneficial where rig availability is low.