Delivering Zonal Isolation between Reservoir Sublayers in Long, Horizontal 12 ¼-in. Hole Sections in Extended Reach Wells

2021 ◽  
Author(s):  
Azza Elhassan ◽  
Ahmedagha Eldaniz Hamidzada ◽  
Toki Takahiro ◽  
Toma Motohiro ◽  
Mohd Waheed Orfali ◽  
...  
Keyword(s):  
High Pressures ◽  
Lessons Learned ◽  
Measurement Tool ◽  
Persistent Problem ◽  
Lost Circulation ◽  
Well Integrity ◽  
Starting Point ◽  
Discharge Policy ◽  
Zonal Isolation ◽  
Fluid Design

Abstract Good cementing practices are required to achieve effective zonal isolation and provide long-term well integrity for uninterrupted safe production and subsequent abandonment. Zonal isolation can be attained by paying close attention to optimizing the drilling parameters, hole cleaning, fluid design, cement placement, and monitoring. In challenging extended reach wells in the UAE, different methods were employed to deliver progressive improvement in zonal isolation. Cementing the intermediate and production sections in the UAE field is challenging because of the highly deviated, long, open holes; use of nonaqueous fluids (NAFs); and the persistent problem of lost circulation. Compounding the problem are the multiple potential reservoirs; the pressure testing of the casing at high pressures after cement is set; and the change in downhole pressures and temperatures during production phases, which results in additional stresses. Hence, the mechanical properties for cement systems must be customized to withstand the downhole stresses. The requirement of spacer fluids with nonaqueous compatible properties adds complexity. Lessons learned from prior operations were applied sequentially to produce fit-for-purpose solutions in the UAE field. Standard cement practices were taken as a starting point, and subsequent changes were introduced to overcome specific challenges. These challenges included deeper 12 ¼-in. sections, which made it difficult to manage equivalent circulating densities (ECDs), and a stricter requirement of zonal isolation across sublayers in addition to required top of cement at surface. To satisfy these requirements, several measures were taken gradually: applying engineered trimodal blend systems to remain under ECD limits; pumping a lower-viscosity fluid ahead of the spacer; using NAF-compatible spacers for effective mud removal; employing flexible cement systems to withstand downhole stresses; and modeling the cement job with an advanced cement placement software to simulate displacement rates, bottomhole circulating temperatures, centralizer placement, mud removal and comply with a zero discharge policy that restricts the extra slurry volume to reach surface. To enhance conventional chemistry-based mud cleaning, an engineered scrubbing additive was included in the spacers with a microemulsion-based surfactant. The results of cement jobs were analyzed by playback in advanced evaluation software to verify the efficiency of the applied solutions. This continuous improvement response to changes in well design has resulted in a significant positive change in cement bond logs; a flexural attenuation measurement tool has been used to evaluate the lightweight slurry quality behind the casing, which has helped in enhancing the confidence level in well integrity in these challenging wells. The results highlight the benefit of developing engineering solutions that can be adapted to respond to radical changes in conditions or requirements.

Implementation of Factory Cementing Concept in the High-Intensity Drilling Environment of Khazzan, Sultanate of Oman

2021 ◽  
Author(s):  
Emmanuel Therond ◽  
Yaseen Najwani ◽  
Mohamed Al Alawi ◽  
Muneer Hamood Al Noumani ◽  
Yaqdhan Khalfan Al Rawahi ◽  
...  
Keyword(s):  
Shallow Water ◽  
High Intensity ◽  
Sultanate Of Oman ◽  
Cement Slurry ◽  
Short Term ◽  
Lost Circulation ◽  
Well Integrity ◽  
Sustained Casing Pressure ◽  
Zonal Isolation ◽  
Casing Pressure

Abstract The Khazzan and Ghazeer gas fields in the Sultanate of Oman are projected to deliver production of gas and condensate for decades to come. Over the life of the project, around 300 wells will be drilled, with a target drilling and completion time of 42 days for a vertical well. The high intensity of the well construction requires a standardized and robust approach for well cementing to deliver high-quality well integrity and zonal isolation. The wells are designed with a surface casing, an intermediate casing, a production casing or production liner, and a cemented completion. Most sections are challenging in terms of zonal isolation. The surface casing is set across a shallow-water carbonate formation, prone to lost circulation and shallow water flow. The production casing or production liner is set across fractured limestones and gas-bearing zones that can cause A- and B-Annulus sustained casing pressure if not properly isolated. The cemented completion is set across a high-temperature sandstone reservoir with depletion and the cement sheath is subjected to very high pressure and temperature variations during the fracturing treatment. A standardized cement blend is implemented for the entire field from the top section down to the reservoir. This blend works over a wide slurry density and temperature range, has expanding properties, and can sustain the high temperature of the reservoir section. For all wells, the shallow-water flow zone on the surface casing is isolated by a conventional 11.9 ppg lightweight lead slurry, capped with a reactive sodium silicate gel, and a 15.8 ppg cement slurry pumped through a system of one-inch flexible pipes inserted in the casing/conductor annulus. The long intermediate casing is cemented in one stage using a conventional lightweight slurry containing a high-performance lost circulation material to seal the carbonate microfractures. The excess cement volume is based on loss volume calculated from a lift pressure analysis. The cemented completion uses a conventional 13.7 - 14.5 ppg cement slurry; the cement is pre-stressed in situ with an expanding agent to prevent cement failure when fracturing the tight sandstone reservoir with high-pressure treatment. Zonal isolation success in a high-intensity drilling environment is assessed through key performance zonal isolation indicators. Short-term zonal isolation indicators are systematically used to evaluate cement barrier placement before proceeding with installing the next casing string. Long-term zonal isolation indicators are used to evaluate well integrity over the life of the field. A-Annulus and B-Annulus well pressures are monitored through a network of sensors transmitting data in real time. Since the standardization of cementing practices in the Khazzan field short-term job objectives met have increased from 76% to 92 % and the wells with sustained casing pressure have decreased from 22 % to 0%.

Obtaining Zonal Isolation in Geothermal Wells

2021 ◽  
Author(s):  
Allam Putra Rachimillah ◽  
Cinto Azwar ◽  
Ambuj Johri ◽  
Ahmed Osman ◽  
Eric Tanoto
Keyword(s):  
Best Practices ◽  
Oil And Gas ◽  
Lessons Learned ◽  
Free Fluid ◽  
High Heating Rate ◽  
Lost Circulation ◽  
Geothermal Well ◽  
Geothermal Wells ◽  
Zonal Isolation ◽  
Primary Cementing

Abstract Cementing is one of the sequences in the drilling operations to isolate different geological zones and provide integrity for the life of the well. As compared with oil and gas wells, geothermal wells have unique challenges for cementing operations. Robust cementing design and appropriate best practices during the cementing operations are needed to achieve cementing objectives in geothermal wells. Primary cementing in geothermal wells generally relies on a few conventional methods: long string, liner-tieback, and two-stage methods. Each has challenges for primary cementing that will be analyzed, compared, and discussed in detail. Geothermal wells pose challenges of low fracture gradients and massive lost circulation due to numerous fractures, which often lead to a need for remedial cementing jobs such as squeeze cementing and lost circulation plugs. Special considerations for remedial cementing in geothermal wells are also discussed here. Primary cement design is critical to ensure long-term integrity of a geothermal well. The cement sheath must be able to withstand pressure and temperature cycles when steam is produced and resist corrosive reservoir fluids due to the presence of H2S and CO2. Any fluid trapped within the casing-casing annulus poses a risk of casing collapse due to expansion under high temperatures encountered during the production phase. With the high heating rate of the geothermal well, temperature prediction plays an important part in cement design. Free fluid sensitivity test and centralizer selection also play an important role in avoiding mud channeling as well as preventing the development of fluid pockets. Analysis and comparison of every method is described in detail to enable readers to choose the best approach. Massive lost circulation is very common in surface and intermediate sections of geothermal wells. On numerous occasions, treatment with conventional lost-circulation material (LCM) was unable to cure the losses, resulting in the placement of multiple cement plugs. An improved lost circulation plug design and execution method are introduced to control massive losses in a geothermal environment. In addition, the paper will present operational best practices and lessons learned from the authors’ experience with cementing in geothermal wells in Indonesia. Geothermal wells can be constructed in different ways by different operators. In light of this, an analysis of different cementing approaches has been conducted to ensure robust cement design and a fit-for-purpose cementing method. This paper will discuss the cementing design, equipment, recommendations, and best available practices for excellence in operational execution to achieve optimal long-life zonal isolation for a geothermal well.

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

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.

Well Integrity Catastrophe Avoided Through Advanced Well Integrity and Reservoir Monitoring Analysis, a Case Study

2021 ◽  
Author(s):  
Mohamed Elyas ◽  
Sherif Aly ◽  
Uche Achinanya ◽  
Sergey Prosvirkin ◽  
Shayma AlSaffar ◽  
...  
Keyword(s):  
Geothermal Gradient ◽  
Root Cause ◽  
Well Integrity ◽  
Reservoir Monitoring ◽  
Precision Temperature ◽  
Zonal Isolation ◽  
Potential Failure ◽  
Corrective Actions ◽  
Thickness Measurements ◽  
Pulsed Neutron

Abstract Well integrity is one of the main challenges that are facing operators, finding the source of the well problem and isolating it before a catastrophic event occurs. This study demonstrates the power of integrating different reservoir monitoring and well integrity logs to evaluate well integrity, identify the underlying cause of the potential failure, and providing a potential corrective solution. Recently, some Injector/producer wells reported migration of injection fluids/gas into shallower sections, charging these formations and increasing the risk of compromised well integrity. Characterization of the well issues required integration of multi-detector pulsed-neutron, well integrity (multi finger caliper, multi-barrier corrosion, cement evaluation, and casing thickness measurements), high precision temperature logs and spectral noise logs. After data integration, detailed analysis was performed to specifically find the unique issues in each well and assess possible corrective actions. The integrated well integrity logs clearly showed different 9.625-inch and 13.375-inch casings leak points. The reservoir monitoring logs showed lateral and vertical gas and water movements across Wara, Tayarat, Rus, and Radhuma formations. Cement evaluation loges showed no primary cement behind the first barrier casing which was the root cause of the problem. Therefore, the proposed solution, was a cement squeeze. Post squeeze, re-logging occurred, validating zonal isolation and a return of a standard geothermal gradient across the Tayarat formation. Most importantly, the cement evaluation identified good bond from the squeeze point clear to surface, isolating all formations. All these wells were returned to service (injector/producer), daily annular pressure monitoring confirmed that no further pressure build up was seen. Kuwait Oil Company managed to avoid a catastrophic well integrity event on these wells and utilized the approach presented to take the proper corrective actions, and validate that the action taken resolved the initial well integrity issues. Consequently, the wells were returned to service, and the company avoided a costly high probability blowout.

scholarly journals Development on Indigenous Homelands and the Need to Get Back to Basics with Scoping: Is there Still "Unceded" Land in Northern Ontario, Canada, with Respect to Treaty No. 9 and its Adhesions?

2021 ◽  
Vol 12 (1) ◽  
pp. 1-49
Author(s):  
Leonard Tsuji ◽  
Stephen Tsuji
Keyword(s):  
Literature Search ◽  
Development Project ◽  
Lessons Learned ◽  
Development Projects ◽  
Northern Ontario ◽  
Starting Point ◽  
Library And Archives Canada ◽  
Bare Minimum ◽  
Comprehensive Literature Search

Scoping includes the establishment of unambiguous spatial boundaries for a proposed development project (e.g., a treaty) and is especially important with respect to development on Indigenous homelands. Improper scoping leads to a flawed product, such as a flawed treaty or environmental impact assessment, by excluding stakeholders from the process. A comprehensive literature search was conducted to gather (and collate) printed and online material in relation to Treaty No. 9 and its Adhesions, as well as the Line-AB. We searched academic databases as well as the Library and Archives Canada. The examination of Treaty No. 9 and its Adhesions revealed that there is unceded land in each of four separate scenarios, which are related to the Line-AB and/or emergent land in Northern Ontario, Canada. Lastly, we present lessons learned from our case study. However, since each development initiative and each Indigenous Nation is unique, these suggestions should be taken as a bare minimum or starting point for the scoping process in relation to development projects on Indigenous homelands.

Engineered Composite Lost Circulation Solution to Successfully Cure Total Losses During Drilling Across Naturally Fractured Formations in Ghawar Gas Field, Saudi Arabia

2021 ◽  
Author(s):  
Faizan Ahmed Siddiqi ◽  
Carlos Arturo Banos Caballero ◽  
Fabricio Moretti ◽  
Mohamed AlMahroos ◽  
Uttam Aswal ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
Circulation System ◽  
Cement Slurry ◽  
Fiber System ◽  
Gas Field ◽  
Well Control ◽  
Lost Circulation ◽  
Carbonate Formation ◽  
Naturally Fractured ◽  
Zonal Isolation

Abstract Lost circulation is one of the major challenges while drilling oil and gas wells across the world. It not only results in nonproductive time and additional costs, but also poses well control risk while drilling and can be detrimental to zonal isolation after the cementing operation. In Ghawar Gas field of Saudi Arabia, lost circulation across some naturally fractured formations is a key risk as it results in immediate drilling problems such as well control, formation pack-off and stuck pipe. In addition, it can lead to poor isolation of hydrocarbon-bearing zones that can result in sustained casing pressure over the life cycle of the well. A decision flowchart has been developed to combat losses across these natural fractures while drilling, but there is no single solution that has a high success rate in curing the losses and regaining returns. Multiple conventional lost circulation material pills, conventional cement plugs, diesel-oil-bentonite-cement slurries, gravel packs, and reactive pills have been tried on different wells, but the probability of curing the losses is quite low. The success with these methods has been sporadic and shown poor repeatability, so the need of an engineered approach to mitigate losses is imperative. An engineered composite lost-circulation solution was designed and pumped to regain the returns successfully after total losses across two different formations on a gas well in Ghawar field. Multiple types of lost-circulation material were tried on this well; however, all was lost to the naturally fractured carbonate formation. Therefore, a lost-circulation solution was proposed that included a fiber-based lost-circulation control (FBLC) pill, composed of a viscosifier, optimized solid package and engineered fiber system, followed by a thixotropic cement slurry. The approach was to pump these fluids in a fluid train so the FBLC pill formed a barrier at the face of the formation while the thixotropic cement slurry formed a rapid gel and quickly set after the placement to minimize the risk of losing all the fluids to the formation. Once this solution was executed, it helped to regain fluid returns successfully across one of the naturally fractured zones. Later, total losses were encountered again across a deeper loss zone that were also cured using this novel approach. The implementation of this lost-circulation system on two occasions in different formations has proven its applicability in different conditions and can be developed into a standard engineered approach for curing losses. It has greatly helped to build confidence with the client, as it contributed towards minimizing non-productive time, mitigated the risk of well control, and assisted in avoiding any remedial cementing operations that may have developed due to poor zonal isolation across certain critical flow zones.

Crack Propagation and Detection in PZT-Multilayer Ceramics

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000091-000098
Author(s):  
Tobias Kühnlein ◽  
Silvan Poller ◽  
Martin Rauscher ◽  
Alexander Klonczynski
Keyword(s):  
Impedance Spectroscopy ◽  
Crack Propagation ◽  
Fracture Strength ◽  
High Pressures ◽  
Mechanical Load ◽  
Matrix Cracking ◽  
Extreme Condition ◽  
Measurement Tool ◽  
Electrode Potentials ◽  
Resonance Frequencies

Piezo multilayer ceramics are increasingly used under extreme condition such as high pressures in engine injection systems. The mechanical stability and reliability of the ceramic multilayer is of major importance for proper operation. Critical functional defects are caused by material fracture and flaw extension in the device. The flaw propagation in PZT-multilayer ceramics under mechanical load was examined using impedance spectroscopy and three-point-bending studies. Initial flaws were generated by applying a sinus ac-field on the specimens. The cracks were successively promoted and after the release of the external mechanical load the impedance spectroscopy was conducted. As a measure for flaw extension, the shift in the resonance frequencies and the sub-resonance height of the impedance spectroscopy was used. A functional dependence of the resonance frequency and the phase shift on the crack length was found. The crack propagation was studied on flaws starting at the positive and negative electrode, respectively. The maximum fracture strength as well as the crack path depends on the electrode potentials. The variation in the fracture strength was caused by the different observed fracture mode: interface cracking, matrix-cracking and a combination of both. The morphology of the fracture faces was ascribed to an anisotropic behaviour, which is created by the sample processing, e.g. the poling process. A modified poling procedure with a lower poling temperature was analysed, which yielded a reduction of the anisotropy of the electrode strength. Impedance spectroscopy was found as a reliable measurement tool for automated flaw detection in PZT-multilayer ceramics.

FIGHTING FRACTURED FLAMINGO—LESSONS FROM RAMBLER-I, TIMOR SEA

1995 ◽  
Vol 35 (1) ◽  
pp. 655
Author(s):  
D. C. Lowry
Keyword(s):  
Lessons Learned ◽  
Open Fractures ◽  
Thick Section ◽  
Well Bore ◽  
Drilling Mud ◽  
Lost Circulation ◽  
Evaluation Strategies ◽  
Timor Sea ◽  
The Right ◽  
Exploration Well

Exploration well Rambler-1, located in the Timor Sea, presented an unusual set of engineering and evaluation problems when drilling a thick section of Flamingo Group (Jurassic–Cretaceous). The well encountered normally pressured open fractures where drilling mud was lost, and at least two mildly overpressured fractures that flowed small quantities of gassy oil into the well-bore. In these circumstances it was difficult to find the right combination of casing, mud density, cement plugs and lost circulation material to drill the well in a controlled and efficient manner.Fine grained sandstone in the Flamingo Group gave moderate mud log shows and two cased-hole RFTs recovered oil. However, cased-hole DSTs of the same intervals recovered only small volumes of filtrate. This remarkable behaviour is attributed to the RFTs recovering oil from porous cement that had been impregnated with oil from the lower of the overpressured fractures.Any future wells drilled near the axis of the Sahul Syncline are likely to encounter similar problems and awareness of the lessons learned in Rambler–1 can improve drilling and evaluation strategies.

Concept Diagramming Software for Engineering Design Support: A Review and Synthesis of Studies

2009 ◽  
Author(s):  
Nathan L. Eng ◽  
Rob H. Bracewell ◽  
P. John Clarkson
Keyword(s):  
Engineering Design ◽  
Design Thinking ◽  
Lessons Learned ◽  
Future Research ◽  
Engineering Practice ◽  
Levels Of Abstraction ◽  
University Of Cambridge ◽  
Starting Point ◽  
Software Interfaces ◽  
The University

Engineering design thinking combines concepts from heterogeneous sources like personal experience, colleagues, digital and hardcopy media. Despite this challenge, modes of thinking across levels of abstraction through multi-dimensional (spatial) representations are widely neglected in digital support systems. This paper aims to summarize lessons learned through years of experience with software tools that augment this visio-spatial conceptual thinking. This work cuts across disciplines to provide a needed, coherent starting point for other researchers to examine complex outstanding issues on a class of promising support tools which have yet to gain widespread popularity. Three studies are used to provide specific examples across design phases, from conceptual design to embodiment. Each study also focuses on an exemplar of diagrammatic software: the University of Cambridge Design Rationale editor (DRed), the Institute for Human Machine Cognition’s (IHMC) CmapTools and the Open University’s Compendium hypermedia tool. This synthesis reiterates how hypermedia diagrams provide many unique, valuable functions while indicating important practical boundaries and limitations. Future research proposed includes: a need to build more diagrammatic literacy into engineering practice, the need for more detailed studies with experts in industry and specific directions for refining the hypermedia diagram software interfaces.

Sign in / Sign up

Export Citation Format

Share Document