‘Level-off’ cement plugging method to cure lost circulation verified with case studies

AbstractControlling lost circulation during drilling operations in a reservoir prone to fluid losses is typically remedied by cement squeezing or plug setting as the last resort. The aim being to minimize or stop drilling fluid losses and to regain full returns at surface, and to maintain wellbore integrity. Different placement methods of cement plugs have been discussed in detail in the literature, except for the ‘level-off’ method, which can be effective for curing complete loss circulation cases. Following modeling and calculations of this cement plug placement method, its design and execution procedures are discussed, together with two successful field cases in highly fractured carbonate reservoirs in the Middle East. Using drill pipe and a Retrievable-Test-Treat-Squeeze (RTTS) packer, set with some spacing from the loss zone, the method entails that the cement slurry is allowed to drop by gravity in order to cure lost circulation. As the column of fluid, mud and slurry in the well exceeds formation pore pressure, i.e., overbalanced conditions, a volume of acid-soluble cement slurry is allowed to slowly drop and freely penetrate the formation, i.e., through its fractures or caverns. During the penetration of this viscous slurry into the loss zone, the cement slurry can set and the fracture or fissure openings are plugged. Presented are detailed design calculations for the level-off placement technique, determination of required cement slurry and displacement volumes, and recommended displacement and RTTS packer setting depths. The expected depth of the top of cement plug is estimated. The design parameters are compared with field cases and explanations are given for possible discrepancies. Success of the operation is discussed in terms of final mud loss after cement plugging and Non-Productive Time mitigation. Detailed field procedures and execution are also presented. The level-off job is already practiced by the industry, but it is not published in the literature, in some cases they have different methods with causing some errors. To the best of authors’ knowledge, this is the first detailed description and stepwise calculation of the level-off cement placement technique in the literature.

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ERD Drilling Record Achieved in the Gulf of Thailand with an Outstanding Drilling Efficiency

10.2523/iptc-21488-ms ◽

2021 ◽

Author(s):

Manchukarn Naknaka ◽

Trinh Dinh Phu ◽

Khamawat Siritheerasas ◽

Pattarapong Prasongtham ◽

Feras Abu-Jafar ◽

...

Keyword(s):

Chemical Elements ◽

Drilling Fluid ◽

Drill Pipe ◽

Oil Field ◽

Technology Selection ◽

Low Flow ◽

Gulf Of Thailand ◽

Directional Drilling ◽

Lost Circulation ◽

The Gulf Of Thailand

Abstract The objective of this research is to describe the methodology used to drill the most extended reach well (ERD) in the Gulf of Thailand. The Jasmine field is a mature, sophisticated, oil field with many shallow reservoir targets that require a minimum 10,000ft horizontal displacement. As such, the main challenges faced, and the novel technology applied is described in detail by this research. The research is an example of successfully drilling a challenging well, safely and efficiently. The Jasmine C – Well X, is a 3-string design structure with an 11-3/4in top hole, an 8-1/2in intermediate section, and a 6-1/8in reservoir horizontal section. Well X was constructed by utilizing an existing platform well slot. The challenge involved drilling from the top hole to the kickoff point and directional drilling away from the casing stump of the existing well to avoid any collision with nearby wells emanating from the Jasmine C platform. The 8-1/2in hole section was the most important segment as it had to reach the landing point precisely in order to start the 6-1/8in section for GeoSteering in the reservoir section. The 8-1/2in section encountered three challenges that could affect drilling efficiency.Directional Drilling – The complexities of the well profile:The method involved making well inclination (INC) lower than 82deg in the tangent interval in order to reduce the well's tortuosity as much as possible.Hole condition – Hole cleaning and fluid losses control:The method involved the use of Low Toxicity Oil Based Mud (LTOBM) CaCO3 system, the chemical elements in the drilling fluid system could help to seal the high permeable zones.Drilling Engineering – Torque and Drag (T&D) control:The method taked into account the 7in casing run to the bottom of the hole, which the casing driven system did not allow for rotation The well was completed successfully without any additional trips. A Total Depth (TD) was of 13,052ftMD was achieved to reach reservoirs at 3,260ft TVDSS. It was therefore announced in 2019 as a new ERD record for Mubadala Thailand (ERD ratio = 3.26, Directional Difficulty Index (DDI) = 6.95). The top hole and 9-5/8in casing were set in the right depth. An 8-1/2in section was accomplished on the planned trajectory with an average on bottom Rate of Penetration (ROP) at 319 ft/hr. The 6-1/8in section was drilled by geosteering to achieve sub-surface objectives. A total of 2,143ft intervals inside the reservoir was successfully achieved. While drilling, lost circulation events occured, but the mud system was conditioned with Lost Circulation Materials (LCM). Therefore, drilling performance was unaffected. Moreover, the Bit's Total Flow Area (TFA) and Rotary steering systems (RSS) flow restrictor was configured to allow directional drilling at a very low Flow rate of 470gpm. Addition, 30 joints of 5-1/2in Heavy Weight Drill Pipe (HWDP) and 39 joints of 4in HWDP were added into the Bottom Hole Assembly (BHA) to transfer string weight to drill bitsand drill to well TD. As complexities of the well profile were fully aware, the casing was runned and minimized the open hole friction until the casing was deployed successfully. In the Gulf of Thailand, drilling the longest ERD well in a shallow True Vertical Depth (TVD) was clearly groundbreaking and entailed the successful management of the key operational challenges related to identification, job planning, design, technology selection, and implementation. This research illuminates the challenges and technical solutions of long ERD well and serves as an example of what can be achieved in the region and globally.

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Experiments on Fluid Placement in a Confined Pipe: Fluid Mechanics Analysis for Plug and Abandonment Applications

Volume 11: Petroleum Technology ◽

10.1115/omae2020-18077 ◽

2020 ◽

Author(s):

Soheil Akbari ◽

Seyed Mohammad Taghavi

Keyword(s):

Oil And Gas ◽

Drilling Fluid ◽

Heavy Fluid ◽

Cement Slurry ◽

Gas Wells ◽

Inflow Velocity ◽

Operation Conditions ◽

Oil And Gas Wells ◽

Cement Plug

Abstract Plug and abandonment (P&A) of oil and gas wells is an essential process to prevent the oil and gas reservoir fluids migration over time and possibly contaminating other formations and also fresh water resources. In order to plug and abandon a well, a high quality cement plug placement is required. One of the most common methods of cement plug placement is the dump bailing method. In this method, a fixed volume of cement is dumped using a bailer on a mechanical plug in the wellbore. The cement slurry occupies the wellbore and also the annular region outside the dump bailer. In the processes of cement slurry placement, an extensive range of Newtonian or non-Newtonian fluids is used to remove the in-situ fluid (drilling fluid or water) in the wellbore. Based on the large number of parameters such as the density and viscosity differences between the fluids, the geometry type (pipe, annulus, etc.), the operation conditions (velocity, geometry inclination, dumping height), various kinds of placement and mixing flows can occur, and different flow regimes (e.g. inertial, viscous) can develop. In this paper, we experimentally study the placement of a heavy fluid to replace an in-situ light fluid in an inclined closed-end pipe (representative of the dump bailing method). The two fluids are Newtonian and miscible, and they have the same viscosity. We investigate the effects of some of the flow parameters such as the dumping height, the pipe inclination, and the inflow velocity of the heavy fluid on the degree of mixing and the placement quality and efficiency. Our results show that the the most efficient displacement happens with the shortest dumping height and at lower inclination from vertical. Also, a high inflow velocity displaces the light fluid promptly with more mixing in comparison with a low inflow rate. The results can help us to develop strategies for improving the dump bailing method in the P&A of the oil and gas wells.

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Engineered Fiber Based Lost Circulation Pill to Abridge Lost Circulation of Geothermal Well

Journal of Earth Energy Science, Engineering, and Technology ◽

10.25105/jeeset.v1i1.3033 ◽

2018 ◽

Vol 1 (1) ◽

Author(s):

Apriyansah Toni ◽

Astra Agus Pramana ◽

Bambang Kustono

Keyword(s):

Base Fluid ◽

Trial And Error ◽

Cement Slurry ◽

Lost Circulation ◽

Severe Loss ◽

Geothermal Well ◽

Flexible Fiber ◽

Geothermal Wells ◽

Surface Section ◽

Cement Plug

<em>Loss circulation is a major problem and known as the biggest challenge during drilling and well construction.This can leadsto various consequences,such as stuck pipe, loss of material and time to combat the losses, and even losing the well itself. Severe loss circulation conditions are often met while drilling geothermal wells in Indonesia. Partial to total losses have start experienced since drilling the surface section. Cement plugs is one of the conventional methods to cure losses. Number of cement plugs differ from one well to another well. Even in some wells, number of cement plugs performed for loss circulation plug can be over 30 times with total of more than 4,000 barrels of cement slurry pumped. Solution other than basic loss circulation material and cement plug must be developed to optimize curing loss time. Engineered fiber base concentration which is include; Base Fluid, LCM and Solid Package was obtained from simulation, then trial and error in laboratory was conducted. Based on the final recipe, the control pill was able to hold pressure and not leaking, even when using 5 mm grid clearance. Additional combined stiff fiber and flexible fiber with concentration of 6 lbs/bbl sufficient to hold exessive loss circulation.</em>

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Successful Application of a Reinforced Composite Mat Pill Technology for Lost Circulation Control in the Norwegian Continental Shelf

10.2118/204062-ms ◽

2021 ◽

Author(s):

Jose A. Barreiro ◽

John S. Knowles ◽

Carl R. Johnson ◽

Iain D. Gordon ◽

Lene K. Gjerde

Keyword(s):

Continental Shelf ◽

Flow Rate ◽

Drilling Fluid ◽

Significant Loss ◽

Lessons Learned ◽

Cement Slurry ◽

Lost Circulation ◽

Reinforced Composite ◽

Zonal Isolation ◽

Norwegian Continental Shelf

Abstract An operator in the Norwegian continental shelf (NCS) required sufficient zonal isolation around a casing shoe to accommodate subsequent targeted injection operations. Located in the Ivar Aasen field, and classified as critical, the well had a 9 ⅝-in. casing shoe set in the depleted Skagerrak 2 reservoir. The lost circulation risk was high during cementing because the Hugin formation, located above the reservoir, contained 40 m [~ 131.2 ft] of highly porous and permeable sandstone. During previous operations in the field, lost circulation was observed before and during the casing running and cementing operations. After unsuccessful attempts to cure the losses with various lost circulation materials, a new solution was proposed to target the specific lost circulation problem by combining two types of reinforced composite mat pill (RCMP) technology. Specifically, the first type of RCMP technology was engineered for use in the viscous preflush spacer, and the second was applied to the cement slurry itself. Working in synergy, the RCMP systems mitigated the risk of incomplete zonal isolation. With no losses observed upon reaching total depth (TD) for the 12 ¼-in. hole, the 9 ⅝-in. casing was run with a reamer shoe and 15 rigid centralizers. Between 2700 and 2728 m [~ 8,858 and 8,950 ft] measured depth (MD), the rig observed constant drag of 30 to 40 MT whilst working the casing down, and circulation was completely lost before partial returns were eventually observed. The rig continued to work the string down to the planned landing depth at 3897 m [~ 12,785 ft] MD. Precementing circulation ensued with staged pump rates increasing at 100-L/min [~ 0.6-bbl/min] intervals up to 1400 L/min [~ 8.8 bbl/min], which induced losses at a rate of 6.5 m3/hour [~ 40 bbl/hour]). Subsequently, the flow rate was reduced to 1300 L/min [~ 8.1 bbl/min], and the annular volume was circulated 2.6 times with full returns. Attempts to reduce equivalent circulating density (ECD) ahead of the cementing operation were implemented at 1300 L/min [~ 8.1 bbl/min] using a low-density, low-rheology oil-based drilling fluid pill. However, a significant loss rate of 18.0 m3/hour [~113 bbl/hour] was observed. The flow rate was reduced to 950 L/min [~ 6.0 bbl/min], and partial circulation was recovered. After the spacer and cement had reached the annulus, full returns were immediately observed and continued until the top plug was successfully bumped. Acoustic logging determined that the operation had achieved the primary job objective of establishing the required length of hydraulically isolating cement in the annulus. Lost circulation is a costly problem that can be difficult to solve, even with the wide variety of technologies available (Vidick, B., Yearwood, J. A., and Perthuis, H. 1988. How To Solve Lost Circulation Problems. SPE-17811-MS). This case study demonstrates a successful solution. The operator will be able to incorporate lessons learned and best practices into future operations, and these lessons and practices will be useful to other operators with similar circumstances.

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A Big Question for Digital Experts: What Is the Driller Trying To Do?

Journal of Petroleum Technology ◽

10.2118/0621-0029-jpt ◽

2021 ◽

Vol 73 (06) ◽

pp. 29-30

Author(s):

Stephen Rassenfoss

Keyword(s):

Situational Awareness ◽

Drilling Fluid ◽

Construction Engineering ◽

Lost Circulation ◽

Drilling Optimization ◽

Fluid Properties ◽

Drilling Operations ◽

Multiple Devices ◽

Drilling Conditions ◽

Fluid Losses

Digital drilling experts spend a lot of time wondering “what was the driller thinking?” They are not being sarcastic. The question matters for those doing analysis or writing control algorithms because the significance of readings, such as level of torque at any moment, depends on what the driller is doing at the time. The interpretation is different if the rig is drilling, where significant torque is required, or reaming, where the resistance is likely minimal. “During the reaming process, a spike in torque indicates something altogether different from a similar spike while drilling. So, the machine must recognize at least these two states: drilling and reaming,” said Fred Florence, a drilling consultant. He is among a group of drilling automation advocates who put rig state on a short list of issues that must be addressed to make it possible to create drilling systems where multiple devices can read and react in sync to changing drilling conditions. In other words, they want to know the information in the driller’s head now, said Moray Laing, director of digital value well construction engineering for Halliburton. That means an automated device needs to know what the driller is doing and also be aware of concerns that could require quick reactions. “Unless we can give it the same situational awareness of a human, it will not be able to manage the complexity of the process,” said Darryl Fett, Total’s manager of research drilling and wells in Houston. Rig state differences also plague those trying to analyze drilling data who need to know what else was going on at the time. They struggle with multiwell data where different methods of calculating the rig state were used. Drillers leave a record of their work in drilling logs. But this after-the-fact report typically lacks the precise timing sought by digital analysts using high-frequency data to analyze events that can happen suddenly. “A data scientist working on drilling will tell you that one of their biggest pains is someone will ask them to build a model on lost circulation and here is some data,” Laing said. That analysis is not possible unless someone can offer details about when the fluid losses began, how long they lasted, and other bits of context that might matter, such as the drilling fluid properties at the time. When asked for a basic explanation of the rig state, Crispin Chatar, drilling subject matter expert for Schlumberger, compared it to bringing a car that has been overheating to the shop. The mechanic will ask what was happening when the trouble began. Did the trouble start while driving fast on a freeway? While stuck in traffic? Did it happen after the radiator fluid warning light went on? “Every single engineer who works in drilling optimization, drilling analytics, or any one of our remote operation centers uses rig state to quickly and clearly understand what is going on at the well-site in terms of drilling operations or what the system might be seeing downhole,” Chatar said.

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Drilling Fluid and Cement Slurry Design for Naturally Fractured Reservoirs

Applied Sciences ◽

10.3390/app11020767 ◽

2021 ◽

Vol 11 (2) ◽

pp. 767

Author(s):

Nediljka Gaurina-Međimurec ◽

Borivoje Pašić ◽

Petar Mijić ◽

Igor Medved

Keyword(s):

Drilling Fluid ◽

Fractured Reservoirs ◽

Naturally Fractured Reservoirs ◽

Cement Slurry ◽

Lost Circulation ◽

Managed Pressure Drilling ◽

The World ◽

Naturally Fractured ◽

Induced Fractures ◽

Bottomhole Pressure

For years, drilling engineers have been faced with the challenge of drilling wells through naturally fractured reservoirs that are present around the world. During drilling, the pressure at the bottomhole of a well is frequently intentionally higher than formation pressure, which can result in the loss of mud in surrounding rocks. During well cementing, the bottomhole pressure is even higher than it is during drilling, because the cement slurry density is higher than the density of the mud. Therefore, if natural or induced fractures in the surrounding rocks are not plugged during drilling, the cement slurry can be lost to them, reducing their permeability which is undesirable in the case of a pay zone. To prevent the loss of circulation and the related consequences, it is necessary to apply good drilling and cementing practices and to use adequate methods and carefully selected materials for plugging the loss zones. The aim of this article is to give an overview of the preventive and corrective methods that can be applied in drilling and cementing through fractured zones as well as improvements in drilling and cementing technology to avoid lost circulation issues (e.g., aerated drilling fluid, casing while drilling, managed pressure drilling, expandable tubulars, lightweight cement slurries, etc.).

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Solidifying Mud Cake to Improve Cementing Quality of Shale Gas Well: A Case Study

The Open Fuels & Energy Science Journal ◽

10.2174/1876973x01508010149 ◽

2015 ◽

Vol 8 (1) ◽

pp. 149-154 ◽

Cited By ~ 5

Author(s):

Jun Gu ◽

Ju Huang ◽

Su Zhang ◽

Xinzhong Hu ◽

Hangxiang Gao ◽

...

Keyword(s):

Shale Gas ◽

Calcium Silicate Hydrate ◽

Drilling Fluid ◽

Cement Slurry ◽

Gas Well ◽

Safety Requirements ◽

Mud Cake ◽

Gas Bearing

The purpose of this study is to improve the cementing quality of shale gas well by mud cake solidification, as well as to provide the better annular isolation for its hydraulic fracturing development. Based on the self-established experimental method and API RP 10, the effects of mud cake solidifiers on the shear strength at cement-interlayer interface (SSCFI) were evaluated. After curing for 3, 7, 15 and 30 days, SSCFI was remarkably improved by 629.03%, 222.37%, 241.43% and 273.33%, respectively, compared with the original technology. Moreover, the compatibility among the mud cake solidifier, cement slurry, drilling fluid and prepad fluid meets the safety requirements for cementing operation. An application example in a shale gas well (Yuanye HF-1) was also presented. The high quality ratio of cementing quality is 93.49% of the whole well section, while the unqualified ratio of adjacent well (Yuanba 9) is 84.46%. Moreover, the cementing quality of six gas-bearing reservoirs is high. This paper also discussed the mechanism of mud cake solidification. The reactions among H3AlO42- and H3SiO4- from alkali-dissolved reaction, Na+ and H3SiO4- in the mud cake solidifiers, and Ca2+ and OH- from cement slurry form the natrolite and calcium silicate hydrate (C-S-H) with different silicate-calcium ratio. Based on these, SSCFI and cementing quality were improved.

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