Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Aviles, Isaac
Abstract Degradable plug-and-perf systems made of degradable alloys and polymers are being used extensively for multi-stage stimulation (MSS). This paper reviews the degradable materials available in the market, including degradable magnesium and aluminum alloys and degradable plastics and elastomers, compares their degradation mechanisms, and discusses the factors affecting their degradation behavior. A series of degradable aluminum alloys with good mechanical properties, and a tunable range of degradation rates were developed in Schlumberger for MSS applications. Key parameters, such as material formulation, temperature, and hydrostatic pressure are used to control the degradation behavior of these degradable alloys. Predictive models are established to predict the degradation time window under a broad range of downhole conditions for improved completions job planning. Comprehensive testing has been done to verify the performance of the materials in the simulated downhole conditions. In addition, field operation results are available to validate the performance of the degradable fracturing plugs made of these degradable alloys. Degradable materials enable degradable fracturing plug applications and eliminate the need for mechanical intervention. They receive more and more attention in the MSS market. We will see more rapid growth of their applications in the coming years.
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.49)
Technology Update Of all the technologies that have propelled the unconventional boom in the United States over the past 15 years, plug and perf (P&P) remains the No. 1 method for stimulating multistage wells, enabling operators to achieve significant economic gains in previously inaccessible reservoirs. Unconventional wells have become longer, with laterals extending as far as 10,000 ft and beyond. When combined with tighter spacing between stages, this growing lateral length has dramatically increased stage counts. In North American land activity, stages per lateral have nearly doubled in most basins since 2008, thanks in part to increased efficiencies in P&P operations. P&P relies on the use of a wireline or electric line to convey perforating guns and plugs to isolate sections of a reservoir for hydraulic fracturing. After the well is stimulated, the plugs are milled out with some type of mechanical intervention, such as the use of coiled tubing (CT). Over the years, P&P has been improved with the development of composite plugs, as opposed to permanent-style plugs, that can be milled out in a continuous operation, pump-down operations to replace mechanical conveyance, and toe-initiator valves, which eliminate the need to mechanically convey perforations for the initial stage of the P&P operation. Despite these advances, mechanical intervention remains costly and risky, and in some instances may damage the recently placed fractures. In cases of low reservoir pressure or extended-reach laterals, milling can be especially problematic. Returns do not easily reach the surface, and friction and helical buckling effects can often result in CT lockup, preventing the CT from reaching the required depth to remove plugs in the toe section of the well. Debris left behind from milled-out plugs in the wellbore can result in the CT becoming stuck, thus driving up costs and further delaying production. These limitations signaled the need for the industry to move a step beyond conventional P&P technology. A new, dissolvable P&P system eliminates the need for mechanical intervention to remove plugs, enabling an unlimited number of stages to be stimulated. Launched in February, the dissolvable P&P completions system has been successfully implemented in many of the major unconventional plays in North America.
- Geology > Petroleum Play Type > Unconventional Play (0.34)
- Geology > Rock Type (0.30)
Technology Update A highly efficient and popular technique for multistage fracturing involves placing a completion string in the open hole with a series of ball-actuated stages isolated by hydraulically set or swellable packers. This practice has been instrumental to the increase of activity in hydrocarbon-bearing reservoirs, as it allows continuous operation while performing a large number of stimulation treatments. When using this technique, sections of the reservoir can be selectively accessed by pumping actuators, or frac balls, from surface that land on correspondingly sized seats that have progressively larger diameters as operations advance from toe to heel. When all stages have been treated, the well is allowed toย flow back, flushing the balls back to surface where they are caught in a ballย trap. Despite more than a quarter of a million stages that have been treated using the sliding sleeve technique, the results are not always up to expectation. Operators have experienced sub-optimal production from wells in which logs and tests indicated high productivity. In searching for a root cause, it has been discovered that often not all balls are recovered. Further investigation has sometimes found that balls may have deformed and become jammed in their seats, plugging all production from beneath. The only solution is to trip into the well and mill out the seats. Aside from the added cost and risk, the challenge is that this undesirable situation is difficult to identify because other reservoir problems that milling will not solve can present a similar production profile. This adds uncertainty to any decision to mill out the system. Frac balls are typically made from phenolic or composite materials. The composite material is laminated and, depending upon the orientation of the laminar planes, it can fracture when it seats and is subjected to additional hydraulic pressure during fracturing operations. If the ball fractures before it has served its purpose, the entire job may be jeopardized. Both types of balls are subject to deformation, often referred to as egging, when under pressure (Fig. 1). Slight egging can cause the ball to stick in the upper seats when the well is put on production, or the ball can jam itself into the seat so tightly that the only way to remove it is by milling. A stuck or jammed frac ball acts as a permanent isolation point for all treated stages below it.
Abstract During the past decade, the completion technique used in liquid-richun conventional plays in North America has undergone a transformation. Today, the vast majority of completions in these areas are open-hole (OH) graduated ball-drop fracturing isolation systems. This preferred completion type for horizontal wells is driven by the efficiency gains in fracturing operations and the production gains when compared to previously used completion techniques. Thousands of open-hole fracturing systems are run each year, with a continuously growing stage count. Graduated ball-drop type completions rely on a sliding sleeve activated by a ball dropped from surface. Each ball travels the length of the lateral well to its intended operational depth, at which it meets a mated seat and isolates the wellbore below. Once the ball is in position, the sliding sleeve opens via the hydraulic force on the ball and seat, allowing a fracturing stage to commence. This dual function of the ballโactivation and sealingโis of extreme importance for the stimulation treatment process. If the ball fails, it will result in bypassed pay zones and unintentional refracturing of previously stimulated zones. Although sometimes surface pressures can be used to infer ball behavior, often the pressure signals observed at surface cannot guarantee successful ball performance. This paper will present an extensive study of ball performance under pressure for the most common ball materials in the industry. Phenolic, composite and metal alloy materials were explored with the pros and cons for each investigated. In particular three main areas were analyzed:molding, layering and extrusion of material versus inconsistencies in ball performance; ball deformation at high pressure versus pressure required to bring the ball off seat; and comparison of the performance of phenolic, composite and metal alloy materials for ball fabrication and their performance at high temperature. Manufacturing variability is also explored on this paper. The impact on the manufacturing process on the performance of balls made of the same material is presented by means of laboratory experimentation. The conclusions from this paper provide operators the necessary information to consider when making completion and ball material decisions in their field operations. In particular, the results of this testing may illuminate some previously unexplainable occurrences in graduated ball sliding-sleeve systems. This testing clarified that not all fracturing balls pumped in horizontal wells perform equivalently under wellbore fracture conditions.
- Asia > Middle East (0.93)
- North America > United States > Texas (0.46)
- Well Drilling > Drilling Operations > Directional drilling (0.89)
- Well Completion > Hydraulic Fracturing > Multistage fracturing (0.88)
- Well Completion > Completion Selection and Design > Completion equipment (0.88)
- Well Completion > Completion Monitoring Systems/Intelligent Wells > Flow control equipment (0.75)
Abstract During the past decade, the completion technique used in liquid-rich unconventional plays in North America has undergone a transformation. Today, the vast majority of completions in these areas are open-hole (OH) graduated ball-drop fracturing isolation systems. This preferred completion type for horizontal wells is driven by the efficiency gains in fracturing operations and the production gains when compared to previously used completion techniques. Thousands of open-hole fracturing systems are run each year, with a continuously growing stage count. Graduated ball-drop type completions rely on a sliding sleeve activated by a ball dropped from surface. Each ball travels the length of the lateral well to its intended operational depth, at which it meets a mated seat and isolates the wellbore below. Once the ball is in position, the sliding sleeve opens via the hydraulic force on the ball and seat, allowing a fracturing stage to commence. This dual function of the ballโactivation and sealingโis of extreme importance for the stimulation treatment process. If the ball fails, it will result in bypassed pay zones and unintentional refracturing of previously stimulated zones. Although sometimes surface pressures can be used to infer ball behavior, often the pressure signals observed at surface cannot guarantee successful ball performance. This paper will present an extensive study of ball performance under pressure for the most common ball materials in the industry. Phenolic, composite and metal alloy materials were explored with the pros and cons for each investigated. In particular three main areas were analyzed: 1) molding, layering and extrusion of material versus inconsistencies in ball performance; 2) ball deformation at high pressure versus pressure required to bring the ball off seat; and 3) comparison of the performance of phenolic, composite and metal alloy materials for ball fabrication and their performance at high temperature. The conclusions from this paper provide operators the necessary information to consider when making completion and ball material decisions in their field operations. In particular, the results of this testing may illuminate some previously unexplainable occurrences in graduated ball sliding-sleeve systems. This testing clarified that not all fracturing balls pumped in horizontal wells perform equivalently under wellbore fracture conditions.
- Asia > Middle East (0.93)
- North America > United States > Texas (0.28)
- North America > Canada > Alberta (0.28)
- Well Drilling > Drilling Operations > Directional drilling (0.89)
- Well Completion > Hydraulic Fracturing > Multistage fracturing (0.88)
- Well Completion > Completion Selection and Design > Completion equipment (0.88)
- Well Completion > Completion Monitoring Systems/Intelligent Wells > Flow control equipment (0.75)
Abstract The Eagle Ford shale is a hydrocarbon-producing formation of significant importance due to its capability for producing at high-liquid/gas ratios, more so than other traditional shale plays. Situated in south Texas, the total Eagle Ford liquids production in 2007 was less than 21,000 bbl total. In 2011, production averaged 65,500 BOPD in the play (EIA, 2011). Activity in the Eagle Ford continues to increase because the benefits from producing high liquid yields across much of the play, along with attractive commodity prices, have made the Eagle Ford a more attractive development over many other shale reservoirs. The rapid development of the Eagle Ford shale was enabled by horizontal drilling. In 2007 none of the reported production was from horizontal wells. In 2011 alone over 2,800 drilling permits were issued, virtually all of them for horizontal wells (RigData, 2012). The Eagle Ford shale has low-clay content, high-carbonate content, and is in an extensional basin, making it conducive to somewhat complex hydraulic fracturing (Martin et al, 2011). The plug and perforating technique has become the preferred completion method in the play due to multiple entry points creating complex fractures at a minimal cost. This completion technique requires a mechanical means for conveying perforating guns, such as coiled tubing (CT), wireline tractor or stick pipe, for the first fracturing stage at the toe of the well. To streamline their completion process, an Eagle Ford operator chose to use an initiator valve that is run at the toe of the well as part of the final completion design. This pressure activated valve is capable of initiating operations on the first fracturing stage without the need for CT or other mechanical means of conveyance of perforating guns. Simple and robust, the valve is activated by a pressure increase from the surface. The valve uses a rupture disc for precise activation and a helical port design that allows for hydraulic fracturing to be performed through the valve into the cement and the formation. With over a dozen wells completed in the Eagle Ford formation by the operator, the valve has provided logistical and economic benefits to the streamlined completion process. This paper describes the initiator valve completion tool and its application in the Eagle Ford shale. A case history is presented to show the specific design and operation of the initiator valve, as well as its benefits over other completion practices that target the first stage in a closed lateral system. Detailed activation of the valve and fracturing data through the valve are also presented.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.55)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- (24 more...)
Technology Update Plug-and-perf completions have proved to be the most flexible multistage well completion schemes. The main reason is that each stage can be perforated and treated optimally because options can be exercised right up to the moment the perforating gun is fired. This allows the engineer to apply knowledge from each previous stage to the stage under treatment. For example, using real-time microseismic fracture mapping techniques provides a view of where previous fractures have propagated, which enables adjustments to be made to perforating depth and pumping schedules for subsequent stages. Some people have argued that the plug-and-perf technique is too time consuming and that it is too slow at the start because of the need to run the first stage perforating guns in with coiled tubing, stick pipe, or a downhole tractor, thus adding an unnecessary expense. A new technique introduced by Schlumberger adds significant operating efficiency and lowers the cost of cemented, multistage fracturing by eliminating the initial perforating run. The technique uses the KickStart pressure-activated rupture disk valve to enable the first stage treatment to be combined with casing operations. In addition to reducing downtime, the technique has been shown to lower fracture initiation pressure, thereby eliminating the risk of closed perforation tunnels caused by shale swelling, and to increase the likelihood of fracturing the stage toย completion. The extensive study of geomechanics has shown that rock formations fracture at their weakest point and that the weakest point aligns with the plane of maximum horizontal stress whenever the overburden (vertical) stress exceeds lateral stresses, which occurs most of the time. The pressure-activated rupture disk valve has a unique helical port design that exposes the formation outside the casing to fracture pressure, thereby ensuring that the fracture will align with the maximum horizontal stress plane and propagate at the weakest point in the formation. A major benefit of this alignment is the reduction of tortuosity at the fracture initiation point, which significantly reduces the probability of a premature screenout of the initial fracture treatment at the toe of the completion.
- Geophysics > Seismic Surveying > Passive Seismic Surveying > Microseismic Surveying (0.55)
- Geophysics > Borehole Geophysics (0.50)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- (2 more...)
Abstract The Bakken is one of the most active basins in the world in terms of number of rigs, with over 200 operating on the US side of the US-Canadian border. Production has rapidly increased from 100,000 BOPD in 2005 to 600,000 BOPD in 2012 in the state of North Dakota with the majority of production coming from the Bakken (Uptream Online, 2012). Greater horizontal drilling activity and a continuing increase in the number of hydraulic fracture stages per lateral have helped North Dakota grow its oil production six-fold in just seven years. The Bakken is a fairly tight dolomitic siltstone requiring hydraulic fractures to produce economically. The stage count for hydraulic fracture treatments averaged nearly three stages in early 2007 and increased steadily over time to nearly 30 stages in late 2011. Some wells have even been completed with 40 or more stages. With the ever increasing stage count, the question remains: has the economic stage count limit been reached in the Bakken? This paper analyzes the stage count versus the production impact of horizontal Bakken wells to determine if the economic stage count has been reached in the play. Wells are grouped and analyzed based on geographic considerations to help normalize for changes in geologic attributes such as natural fractures, reservoir quality, and net pay. Lateral length was also taken into account as varied lengths can impact stage spacing and interference issues. Analyses were run with various oil and well service costs to determine how the economic stage count may change over time. If the economic limit was not reached under certain circumstances, this paper analyzes possible scenarios to determine when the economic stage count would be reached. This approach should provide insight into how other unconventional oil plays can evolve in the future.
- North America > United States > South Dakota (1.00)
- North America > United States > Montana (1.00)
- North America > United States > North Dakota > McKenzie County (0.67)
- North America > United States > North Dakota > Mountrail County (0.46)
- Geology > Petroleum Play Type (1.00)
- Geology > Geological Subdiscipline (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.67)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.87)
- North America > United States > Texas > Fort Worth Basin > Sherman Basin > Sadler Field (0.99)
- North America > United States > Texas > East Texas Salt Basin > Fairway Field > James Lime Formation (0.99)
- North America > United States > South Dakota > Williston Basin > Bakken Shale Formation (0.99)
- (18 more...)
An Efficient Horizontal Cased Hole Multistage Stimulation Well: China Case Story
Liu, Guang Hua (PetroChina Dagang Oilfield Company) | Cui, Hui Kai (PetroChina Dagang Oilfield Company) | Fould, Jeremie (Schlumberger) | Lee, JS (Schlumberger) | Wang, Hai Long (Schlumberger) | Zhang, Xing Guo (Schlumberger) | Aviles, Isaac (Schlumberger) | Baihly, Jason (Schlumberger)
Abstract Drilling activity has been steadily ramping up in China to meet the countries energy demand and government production goals. This is moving some activity to previously unexploited โtightโ formations requiring hydraulic fracturing to produce economically. These formations have historically been producing with stimulated vertical wells and some horizontal un-stimulated wells. Many of these tight reservoirs exist in the Bohai Basin of Eastern China. In order to quickly ramp up production to meet the governmentsโ goals, new drilling and completion techniques are being used including completing horizontal wells with multistage hydraulic fractures in some fields. In some low producing areas new methods of isolating and stimulating wells are being investigated by the operator. New stimulation isolation methods must be streamlined as much as possible in order to achieve the production goals quickly and economically. One of the new completion systems that was developed for cemented wells requiring multistage stimulation us generically called the treat and produce (TAP) completion system. This high efficiency completion system has recently been used in Chinaโs Dagang field to stimulate a horizontal well. The TAP system was run by the operator in the Dagang field, where cased and cemented vertical completions are common and require artificial lift to produce. Horizontal cemented completions have been recently introduced as a means to increase field wide production. Although plug and perforating methods are applicable for these wells, the client turned to a more efficient solution. TAP systems permit continuous pumping operations to be performed while precisely placing multiple hydraulic fracture treatments along the horizontal section; immediate flowback is possible for further production and efficiency gains. In order to efficiently complete the horizontal well, a treat and produce (TAP) system was used in order to complete the well. This completion system uses a series of sliding sleeve valves that are installed as part of the casing string. These valves are actuated by pressure and sliding sleeves with graduated ball seats. This paper describes the TAP completion system and its application in the Dangang field in China. TAP completions enabled optimized fractures placement and propagation in cemented completions that resulted in efficiency and production gains for the client, proving the application for the field. By means of a case history, the specific design and operation of the TAP completions system are discussed.
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Green Canyon > Block 237 > Green Canyon 237 Field > Wang Well (0.99)
- Asia > China > Tianjin > Bohai Basin > Huanghua Basin > Dagang Field (0.99)
- Asia > China > Bohai Basin (0.99)
- North America > United States > Louisiana > China Field (0.97)
ABSTRACT The James Lime is a carbonate formation located along the United States Gulf of Mexico upper coast. Exploration wells were drilled in the James Lime beginning in the 1950's, with commercial activity occurring in the following decade. Wells were drilled exclusively vertical from its discovery through the late 1990's. Over this timeframe, these wells had a great deal of variability in production which hindered the development of the play. Given the apparent rock potential, the production results from these types of completions were oftentimes disappointing and uneconomical. Many different types of drilling and completion technologies have been attempted over the history of the James Lime in order to improve production results. Little has been publicly documented on the impact of these step changes attempted on the James Lime. One striking technological innovation occurred in the late 1990's when operators started drilling wells horizontally in the James Lime. Initially these wells were either not stimulated or completed with a single stage hydraulic fracturing treatment. Just drilling horizontally had little impact on production results and consistency. Within a few years of horizontal development, wells started to be hydraulically fractured with multiple treatment stages using advanced open-hole multistage isolation systems. These two technological innovations along with others had an impact on increasing James Lime production over time. (IHS, 2011) This paper analyzes the various drilling and completion technologies that have been applied to the James Lime over its 50 year history. The impact on production of these practices since 1995 is also presented. Some of the variants analyzed to determine their impact on production include hole direction, lateral length, completion isolation system, and number of stages treated. Hydraulic fracturing treatment details such as proppant type, treatment volume, and proppant volume were analyzed to determine their impact on production results as well. Other factors were taken into consideration when performing the production analysis including the timeframe when the well was drilled and completed. The results of this analysis uncovered the impact on production that technological advancements had over time on the tight James Lime carbonate formation. It highlights the key production drivers in the James Lime and how to improve production of future wells drilled in the formation. Furthermore, the lessons learned and key technologies from this formation can be applied to other tight carbonate plays around the world.
- Geology > Geological Subdiscipline (1.00)
- Geology > Rock Type > Sedimentary Rock > Carbonate Rock (0.46)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- (5 more...)