Repeatedly Increased Efficiency and Success Rate from a New Solids-Cleanout Process Using Coiled Tubing: A Review of Recent Achievements from Over 100 Operations

Sach, Manfred; Li, Jeff

doi:10.2118/106857-ms

Cited by 15 publications

(5 citation statements)

References 12 publications

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“…Several cleanout techniques have been developed over the years, these include stationary circulation, wiper tripping (1,2,(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) , reverse circulation (19)(20)(21)(22) , sand vacuuming technology (23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)36,37) , and venturi sand/junk bailers (4,22,(38)(39)(40) .…”

Section: Sand Cleanout Methodsmentioning

confidence: 99%

“…Wiper Trip Hole Cleaning (2,(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) A comprehensive experimental test program conducted over the past 15 years (7)(8)(9)(10)(11)(12) has investigated solids transport for both stationary circulation and wiper trip cleanouts. The effect of multiphase flow, rate of penetration (ROP), deviation angle, circulation fluid properties, particle density and size, fluid rheology, pipe eccentricity, wiper trip speed, and nozzle type on solids transport was examined in detail.…”

Section: Conventional Hole Cleaning Methodsmentioning

confidence: 99%

“…Based on this research, an effective solids-cleanout methodology/process using CT [see Figures 4(a) and (4c)] has been developed and proven by field operations (1,2,4,6,(14)(15)(16)(17)(18) . This patented (13) methodology is embodied in a comprehensive solids-transport simulator (10) and the method is further enhanced by a specialized downhole cleanout tool ( Figure 5).…”

Section: Conventional Hole Cleaning Methodsmentioning

confidence: 99%

“…The specialized downhole cleanout tool (6) (Figure 5) offers the option of using downward facing, high-energy jetting nozzles or a positive displacement motor (PDM) to ensure sufficient penetra- tion energy needed for harder solids depositions. Having penetrated the targeted solids [see Figure 4(a)], this specialized "circulation valve" allows the fluid pumped during the cleanout to be redirected to low energy upward facing jets simultaneously stopping the fluid stream through the jetting nozzle or PDM.…”

Section: Conventional Hole Cleaning Methodsmentioning

confidence: 99%

“…For certain more challenging cleanouts, several cleanout stages may be required to reach the required depth (6) . The process of penetrating into the solids to a targeted depth and performing wiper trips can be repeated numerous times during one run in hole.…”

Section: Conventional Hole Cleaning Methodsmentioning

confidence: 99%

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Sand Cleanouts With Coiled Tubing: Choice of Process, Tools and Fluids

Li¹,

Misselbrook²,

Sach³

2010

Journal of Canadian Petroleum Technology

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Summary Cleaning fill from wellbores is the most common coiled tubing (CT) application. The process is a function of multiple variables including fluid properties, flow velocities, wellbore geometry and deviation, pipe eccentricity, particle properties, fill penetration rate and wiper trip speed. Removing fill from wells with low bottom hole pressures (BHP) can be challenging especially if wells are completed with smaller diameter production tubulars which significantly reduce circulation flow cross-section and choke flow(1). Such challenges are further compounded by high deviation or horizontal well trajectories especially in large diameter wellbores. A variety of cleanout methods have been developed in the past, often incorporating high circulation rates, special fluids, wiper trips, or reverse circulation to remove solids. Many of these conventional sand cleanout methods often apply excess hydrostatic pressure on the formation, resulting in lost circulation in pressure depleted reservoirs. The conventional solution to overcome excess hydrostatic pressure has been to include nitrogen to reduce fluid density and thus lessen the hydrostatic head; however, sand vacuuming technology using a concentric coiled tubing (CCT) with a downhole jet pump is an alternative technique for removing fill without placing a hydrostatic load on the reservoir. This paper reviews the individual sand cleanout systems and discusses the advantages and limitations related to each method. In recent years, cleaning sand using the wiper trip method has become the preferred technique. However, an appropriate pump rate and reservoir pressure are needed to maintain a proper return flow rate to carry the sands to the surface. For pressure-depleted reservoirs completed with horizontal wells, a sand vacuuming system can be used to efficiently remove the debris without circulating nitrogen and without high pump rates. When the fill cannot be removed from large-diameter deviated wellbores using conventional low-cost cleanout fluids, then fluids with high solids suspension capability (under shear conditions) in conjunction with wiper tripping may be an economical option. The main application for the reverse circulation technique is cleaning sand from large diameter wellbores when the necessary pump rates for conventional "forward" circulation are not achievable. A venturi junk bailer is often used to retrieve larger or heavier material which cannot be circulated out by traditional methods. Field cases are provided, demonstrating how to select the proper cleaning method and how to efficiently remove sand from a wellbore based on both operational and logistical conditions.

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Section: Sand Cleanout Methodsmentioning

confidence: 99%

Section: Conventional Hole Cleaning Methodsmentioning

confidence: 99%

Section: Conventional Hole Cleaning Methodsmentioning

confidence: 99%

Section: Conventional Hole Cleaning Methodsmentioning

confidence: 99%

Section: Conventional Hole Cleaning Methodsmentioning

confidence: 99%

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Sand Cleanouts With Coiled Tubing: Choice of Process, Tools and Fluids

Li¹,

Misselbrook²,

Sach³

2010

Journal of Canadian Petroleum Technology

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Sand Cleanout with Coiled Tubing: Choice of Process, Tools, or Fluids?

Li¹,

Misselbrook²,

Seal³

2008

Europec/Eage Conference and Exhibition

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Cleaning sand from wellbores is a major part of the coiled tubing (CT) industry. The process is a function of multiple variables including fluid properties, flow velocities, hole size and deviation, pipe eccentricity, particle properties and fill penetration rate and wiper trip speed. It becomes even more challenging to successfully remove fill from wells with low bottom hole pressure (BHP) especially if the well is completed with smaller diameter production tubulars which reduce circulation flow cross-section and choke flow. The problem is further compounded by high deviation or horizontal well trajectories especially in large diameter wellbores. Several cleanout options have been developed in the past, employing a variety of different approaches. CT or conventional jointed pipe often incorporates high circulation rates, special fluids, wiper trip, or reverse circulation mode to remove solids. Many of these conventional sand cleanout methods often apply excess hydrostatic pressure on the formation, resulting in lost circulation in low formation pressure reservoirs. The conventional solution to overcome excess hydrostatic has been to include nitrogen to reduce fluid density and thus lessen the hydrostatic head. Sand vacuuming technology combines a concentric coiled tubing (CCT) string with a downhole jet pump to remove fills without placing hydrostatic loads on the reservoir. This paper reviews the individual sand cleanout systems and discusses the advantages and limitations related to each method. Compared with other processes, cleaning sand using a wiper trip has become the most common and efficient mehtod. However, it needs an appropriate pump rate and reservoir pressure to maintain a proper return flow rate to carry the sands to the surface. For a depleted reservoir and especially for horizontal heavy oil wells, a sand vacuuming system can be used to efficiently remove the debris without circulating nitrogen and without high pump rates. The main application for the reverse circulation technique is cleaning sand from large diameter wellbores and when the necessary pump rates for conventional "forward" circulation are not achievable. Fluids with high solids suspension capability (under shear conditions) may be an economic option when the debris cannot be removed from a large diameter deviated wellbores using more conventional, but lower cost, cleanout fluids. The venturi junk bailer is often used to retrieve larger material or junk which is typically not circulated out by any other methods. Field cases are provided, demonstrating how to select the proper cleaning method and how to efficiently remove sands from a wellbore based on both operational and logistical conditions. Introduction Fill cleanouts with CT have been performed for many years. They account for approx 30% of the services performed with CT. Different cleanout methods have been developed over the decades, employing a number of different techniques and approaches. CT or conventional jointed pipe provides two circulation modes to remove solids: either forward or reverse circulation mode. Using conventional water-based fluids, a conventional sand cleanout method may apply excess hydrostatic pressure on the formation, resulting in some lost circulation to a low formation pressure reservoir 3. If the losses are significant this makes sand removal impossible. Also such losses can seriously damage the formation. Nitrogen can be used to reduce hydrostatics, but this necessitates a very specific job design and execution, and in larger diameter wellbores and especially in horizontal wells can result in using large amounts of nitrogen with corresponding logistical and economic consequences The evolution of CT technology offers a unique solution for this problem. To mitigate challenges associated with large nitrogen requirements a sand vacuuming technology has been developed and proven in field operations worldwide 34. The vacuuming system consists of a specialized downhole jet pump connected to a CCT string. The tool can be operated in three modes: sand vacuuming, well vacuuming and high pressure jetting. The tool provides a localized drawdown wherever it is positioned in the wellbore and is effective in removing sand in the sand vacuuming mode and removing localized mud damage in the well vacuuming mode. The selection of sand cleanout methods has to be based on both logistical and technical issues. Things like equipment cost, reel weight (string length and diameter), and availability/cost of N2 will be deciding issues in many sand cleanout operations. Technical issues include the consideration of formation damage potential, low BHP, small completion tubular and particle size/type of debris.

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Cleanouts With Coiled Tubing in Low-Bottom-Hole Pressure Wellbores

Li¹,

Luft²,

Wilde³

et al. 2008

All Days

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Cleaning debris from a wellbore is a common operation with coiled tubing (CT). Considering that this process is a complex function of fluid properties, flow velocities, hole size, deviation angle and particle properties, it becomes particularly challenging in wells with low bottom hole pressures (BHP). There are two circulation modes involved in conventional sand cleanouts with CT, namely forward and reverse circulation. Either sand cleanout method may apply excess hydrostatic pressure on the formation that can result in loss of circulation and returns, hence making cost effective solids removal impossible as well as potentially damaging the formation. In conventional cleanouts, nitrogen or low density hydrocarbon fluids can be used to reduce hydrostatic pressure; however this necessitates a very careful job design and execution which can require expensive volumes of nitrogen (N2) or hydrocarbon fluids. An alternative technology that combines a concentric coiled tubing (CCT) string with a down hole jet pump to remove solids from a wellbore but without placing any additional hydrostatic pressure on the formation has also proven to be remarkably successful. This paper reviews these different solids cleanout methodologies and summarizes the advantages and limitations related to each method when used in low formation pressure wellbores. New solids transport flow loop test results, related to a hydrocarbon fluid, are summarized and compared with tests using water. Case histories are presented that demonstrate how to select the most appropriate cleaning method based on well conditions. Introduction Sand cleanouts with coiled tubing have been performed for many years and 30 to 40% routine services performed in the coiled tubing industry entail sand cleanouts. In most cases, simply due to the presence of sand in the wellbore, the production rate decreases requiring the sand to be removed. In other cases, it is also a known fact that many CT operations require a cleanout before the main well workover operation can commence-3. Several cleanout options have been developed over the decades employing a number of different approaches and techniques 1. Wellbore cleanouts with coiled tubing or conventional jointed pipe often incorporate high circulation rates, special fluids or reverse circulation mode to remove solids. With high rates and high specific gravity water-based fluids, conventional sand cleanout methods excert excess down hole pressure on the formation that can result in lost circulation of returns in the low formation-pressure reservoirs. This makes sand removal impossible and creates damage to the formation. Nitrogen can be used to reduce hydrostatic pressures, but this necessitates a very specific job design and execution and can require massive amounts of liquid nitrogen in the case of horizontal wells that can create further logistical problems when these are located in some remote area. The evolution of coiled tubing technology has brought a unique opportunity for a solution for this problem. Sand/well vacuuming technology has been developed, patented, and proven by field operations to readily clean out a wellbore with low pressure. The sand/well vacuuming system consists of a specialized down hole jet pump connected to a CCT string. The tool can be operated in two modes: sand vacuuming and well vacuuming. The tool induces a localized drawdown in pressure as it passes any point in the wellbore, which effectively removes flow-obstructing sand in the sand vacuuming mode or localized mud damage debris in the well vacuuming mode. The selection of sand cleanout methods must be based on both logistical and technical issues. Equipment costs, reel weight, availability and/or costs of N2 etc. may be the deciding factors for some sand cleanout operations. Technical considerations typically include formation damage potential (i.e. production engineers may not want to pump gel in certain regions), low BHP and/or small completion tubular (i.e. insufficient circulation with N2 required for conventional cleanout systems) and particle size and/or type of debris.

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Repeatedly Increased Efficiency and Success Rate from a New Solids-Cleanout Process Using Coiled Tubing: A Review of Recent Achievements from Over 100 Operations

Cited by 15 publications

References 12 publications

Sand Cleanouts With Coiled Tubing: Choice of Process, Tools and Fluids

Sand Cleanouts With Coiled Tubing: Choice of Process, Tools and Fluids

Sand Cleanout with Coiled Tubing: Choice of Process, Tools, or Fluids?

Cleanouts With Coiled Tubing in Low-Bottom-Hole Pressure Wellbores

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