Application of Wellbore Strengthening Techniques in Carbonate Formation Solves Lost Circulation Challenges During Liner Running and Cementing

2021 ◽  
Author(s):  
Muneer Al Noumani ◽  
Younis Al Masoudi ◽  
Mohammed Al Mamari ◽  
Yaqdhan Al Rawahi ◽  
Mohammed Al Yaarubi ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Well Performance ◽  
Design Work ◽  
Lost Circulation ◽  
The North ◽  
Carbonate Formation ◽  
Zonal Isolation ◽  
Isolation Requirements ◽  
Wellbore Strengthening

Abstract For many years, the oil and gas industry has deployed techniques which enhance formation strength via the successful propping and plugging of induced fractures. Induced fracture sizes have been successfully treated using this method up to the 600 – 1,100-micron range. Static wellbore strengthening techniques are commonly deployed to cover 1,000 micron and all fracture size risks underneath. The deployment of wellbore strengthening techniques has historically been confined to permeable formations. In most cases, wellbore strengthening has been deployed to operationally challenging sand fracture gradients or, where boundaries are pushed, lower ranges of permeability, such as silts. The subject of wellbore strengthening in shales or carbonates to this day, remains a challenge for the industry, with very few documented success stories or evidence of sustained ability to enhance fracture gradient across a drilling campaign. This paper covers the history of lost circulation events which have been reported in the Khazzan/Ghazeer field in the carbonate Habshan formation. It also describes the design changes which were introduced to strengthen the rock and enable circulation/returns, during liner cementation. The design work built on experience applying wellbore strengthening techniques in carbonates in the Norwegian sector of the North Sea. This work is also summarized in this paper. The Habshan carbonate formation in Oman presents a lost circulation challenge through an ‘induced’ fracture risk. Since the beginning of the drilling campaign in the Khazzan/Ghazeer field, the Habshan formation has repeatedly experienced induced mud losses during well activities such as liner running, mud conditioning with liner on bottom and cementing, when the formation is exposed to higher pressures, less so during drilling. The Habshan challenge in Oman has led to regular, significant lost circulation events during cement placement, adding operational cost and more importantly, presenting difficulties around meeting zonal isolation objectives. Through previous field experience in Norway, a set of criteria was developed to qualify a standard pill approach to carbonate strengthening. The currently deployed strategy is designed to address both the risk of induced fracture by propping and plugging (wellbore strengthening) and provide some ability to seal natural fractures which are often encountered with carbonates, or similarly flawed rocks. The strategy deployed aims to cover these two risks with a blanket approach to lost circulation risk in carbonates. The success of this approach is demonstrated using well performance data from a total of 43 wells drilled before and after the introduction of the wellbore strengthening strategy. As it was initially assumed that wellbore strengthening could not be applied to carbonate formations, other techniques had been tried to prevent lost circulation. Those techniques provided mixed results. Since the implementation of wellbore strengthening significant improvements in achieving zonal isolation requirements and reducing fluid losses have been documented.

Overcoming Lost Circulation Risks in Low Fracture Gradient Formations with a New Tailored Spacer System

2021 ◽  
Author(s):  
Kory Hugentobler ◽  
Joseph M. Shine ◽  
Alejandro De La Cruz Sasso ◽  
Abdulmalek Shamsan ◽  
Sandip Patil ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Performance Testing ◽  
Lost Circulation ◽  
Oil And Gas Operations ◽  
Primary Cementing ◽  
Isolation Requirements ◽  
And Performance ◽  
Wellbore Strengthening ◽  
Placement Success ◽  
Fracture Gradient

Abstract In certain regions of oil and gas operations, lost circulation is a common occurrence, especially when a majority of the openhole exposed during primary cementing is carbonate-based formations. This can lead to lost circulation risks in most applications. To overcome lost circulation risks during primary cementing, a new tailored spacer system shows to improve the cement placement success. The manuscript discusses the quality assurance and performance testing with field cases demonstrating the value contributions of the spacer for achieving zonal isolation requirements as well as the top of cement objectives. The work efforts presented shows a spacer meeting and sometimes showing incremental wellbore strengthening in comparison to the published literature for existing available spacers used to overcome similar lost circulation risks.

A Novel Corrosion Monitoring and Prediction System Utilizing Advanced Artificial Intelligence

2021 ◽  
Author(s):  
Klemens Katterbauer ◽  
Waleed Dokhon ◽  
Fahmi Aulia ◽  
Mohanad Fahmi
Keyword(s):  
Real Time ◽  
Oil And Gas ◽  
Salt Water ◽  
Oil And Gas Industry ◽  
Training Dataset ◽  
Metal Loss ◽  
Corrosion Monitoring ◽  
Prediction System ◽  
Well Performance ◽  
Data Driven Approach

Abstract Corrosion in pipes is a major challenge for the oil and gas industry as the metal loss of the pipe, as well as solid buildup in the pipe, may lead to an impediment of flow assurance or may lead to hindering well performance. Therefore, managing well integrity by stringent monitoring and predicting corrosion of the well is quintessential for maximizing the productive life of the wells and minimizing the risk of well control issues, which subsequently minimizing cost related to corrosion log allocation and workovers. We present a novel supervised learning method for a corrosion monitoring and prediction system in real time. The system analyzes in real time various parameters of major causes of corrosion such as salt water, hydrogen sulfide, CO2, well age, fluid rate, metal losses, and other parameters. The data are preprocessed with a filter to remove outliers and inconsistencies in the data. The filter cross-correlates the various parameters to determine the input weights for the deep learning classification techniques. The wells are classified in terms of their need for a workover, then by the framework based on the data, utilizing a two-dimensional segmentation approach for the severity as well as risk for each well. The framework was trialed on a probabilistically determined large dataset of a group of wells with an assumed metal loss. The framework was first trained on the training dataset, and then subsequently evaluated on a different test well set. The training results were robust with a strong ability to estimate metal losses and corrosion classification. Segmentation on the test wells outlined strong segmentation capabilities, while facing challenges in the segmentation when the quantified risk for a well is medium. The novel framework presents a data-driven approach to the fast and efficient characterization of wells as potential candidates for corrosion logs and workover. The framework can be easily expanded with new well data for improving classification.

The Limitation of Reservoir Saturation Logging Tool in a Case of a Deeper Reservoir Flow into a Shallower Reservoir Within the Same Wellbore

2021 ◽  
Author(s):  
P. Merit Ekeregbe
Keyword(s):  
Decision Making ◽  
Flow Condition ◽  
Oil And Gas ◽  
Static Condition ◽  
Oil And Gas Industry ◽  
Well Performance ◽  
Liquid Loading ◽  
Critical Rate ◽  
Logging Tool ◽  
Historical Production

Abstract Saturation logging tool is one key tool that has been successfully used in the Oil and Gas Industry. As important as the tool is, it should not be mistaken for a decision tool, rather it is a tool that aids decision making. Because the tool aids decision making, the decision process must be undertaken by interdisciplinary team of Engineers with historical knowledge of the tool and the performance trend of the candidate well and reservoir. No expertise is superior to historical data of well and reservoir performance because the duo follows physics and any deviation from it is attributable to a misnomer. The decision to re-enter a well for re-perforation or workover must be supported by historical production and reasonable science which here means that trends are sustained on continuous physics and not abrupt pulses. Any interpretation arising from saturation logging tools without subjecting same to reasonable science could result in wrong action. This paper is providing a methodology to enhance thorough screening of candidates for saturation logging operations. First is to determine if the candidate well is multilevel and historical production above critical gas rate before shut-in to screen-out liquid loading consideration. If any level is plugged below any producing level, investigate for micro-annuli leakage. All historical liquid loading wells should be flowed at rate above critical rate and logged at flow condition. Static condition logging is only good for non-liquid loading wells. The use of any tool and its interpretation must be subjective and there comes the clash between the experienced Sales Engineer and the Production/Reservoir Engineer with the historical evidence. A simple historical trending and analysis results of API gravity and BS&W were used in the failed plug case-study. Further successful investigation was done and the results of the well performance afterwards negated the interpretation arising from the saturation tool which saw the reservoir sand flushed. The lesson learnt from the well logging and interpretation shows that when a well is under any form of liquid loading, interpretation must be subjective with reasonable science and historical production trend is critical. It is recommended that when a well is under historical liquid loading rate, until the rate above the critical rate is determined, no logging should be done and when done, logging should be at flow condition and the interpretation subject to reasonable system physics.

Failure Mechanisms of the Wellbore Mechanical Barrier Systems: Implications for Well Integrity

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Shawgi Ahmed ◽  
Saeed Salehi
Keyword(s):  
Oil And Gas ◽  
Failure Mechanisms ◽  
Oil And Gas Industry ◽  
Well Performance ◽  
Acidic Gases ◽  
Well Integrity ◽  
Elastomeric Materials ◽  
Main Motive ◽  
Geothermal Wells ◽  
Mechanical Barrier

Abstract Energy sustainability is the main motive behind the evolution of the concept of well integrity in the oil and gas industry. The concept of well integrity adopts technical, operational, environmental, organizational, and safety measurements to secure the energy supply throughout the life of the well. Technically, a high quality well performance can be maintained by establishing robust barrier systems that are responsible for preventing, controlling, and mitigating potential risks that could arise during the well life cycle. A barrier system is conventionally nested from one or multiple elements that act individually or collectively to scaffold the well integrity. The protection layers in a wellbore can be lost if the integrity of the barrier system is compromised according to the failure of one or all of its elements. Failure can be triggered by technical or non-technical factors. In this study, technical aspects that drive barrier failure mechanisms have given more emphasis. The failure mechanisms of the key mechanical barrier systems, such as casing strings, cement, diverters, blowout preventers (BOPs), production stream valves, and seal assemblies, have been thoroughly investigated. In this study, a comprehensive review of barriers failure mechanisms has been conducted to identify the roots of failures and to outline some of the essential safety measures adopted to avoid the loss of well control. The major findings of this paper revealed that well barrier systems are highly susceptible to failure in unconventional reservoirs, deep and ultra-deep offshore wells, and geothermal wells. The predominant failures identified are casing collapse resulting from cyclic loads, cement percolation by gas migration, cement carking by hoop stress, BOPs wear and tear promoted by frequent tests, and elastomeric materials disintegration caused by acidic gases. Considering these failure mechanisms while designing a wellbore can help the engineers improve the construction quality. In addition, it can assist the operation and maintenance crews in optimizing safe operation boundaries.

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.

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.

Wellhead Movement Analysis and Surface Casing Integrity in Pre-Salt Wells

2021 ◽  
Author(s):  
Fabio Sawada Cutrim ◽  
Charlton Okama De Souza ◽  
Bruno Sergio Pimentel De Souza
Keyword(s):  
Structural Model ◽  
Oil And Gas ◽  
Movement Analysis ◽  
Oil And Gas Industry ◽  
Safety Factors ◽  
Foundation Design ◽  
Gas Industry ◽  
Lost Circulation ◽  
Axial Movement ◽  
Salt Dissolution

Abstract As a general practice in the oil and gas industry, the well foundation, composed by the conductor and the surface casing, is designed with a strict tolerance regarding cement shortfall on the surface casing. However, in a pre-salt scenario, in order to reduce the costs of well construction, the surface casing shoe generally reaches the top of salt. In this case, it is quite hard to make the cement job reach the mudline due to problems like salt dissolution (generating high calipers) and presence of many geological faults in the post-salt zone (which can work as a lost circulation area). Besides that, an evaluation of the wellhead movement is necessary so that the structural restrictions of subsea equipment connected to the wellhead are not violated. This work had the goal of presenting a coupled structural model to analyze the foundation of a subsea well with a partially cemented surface casing, where the safety factors of surface casing are evaluated in the whole well life cycle along with the wellhead movement due to the loads related to each step of this cycle. A sensitivity analysis on the top of cement (measured from the casing shoe) is made, varying it from 300 m to 800 m. The results showed wellhead movement consistent with what is observed in the field, once no axial movement has been reported. Additionally, it was highlighted that the foundation design depends on the operations during the well construction and its future purpose, production or injection, because the thermal loads associated with operations have different impacts.

scholarly journals Proper Use of Technical Standards in Offshore Petroleum Industry

2020 ◽  
Vol 8 (8) ◽  
pp. 555 ◽  
Author(s):  
Dejan Brkić ◽  
Pavel Praks
Keyword(s):  
Large Scale ◽  
Oil And Gas ◽  
Petroleum Industry ◽  
Health And Safety ◽  
Oil And Gas Industry ◽  
European Economic Area ◽  
The European Union ◽  
Technical Standards ◽  
The North ◽  
Offshore Petroleum

Ships for drilling need to operate in the territorial waters of many different countries which can have different technical standards and procedures. For example, the European Union and European Economic Area EU/EEA product safety directives exclude from their scope drilling ships and related equipment onboard. On the other hand, the EU/EEA offshore safety directive requires the application of all the best technical standards that are used worldwide in the oil and gas industry. Consequently, it is not easy to select the most appropriate technical standards that increase the overall level of safety and environmental protection whilst avoiding the costs of additional certifications. We will show how some technical standards and procedures, which are recognized worldwide by the petroleum industry, can be accepted by various standardization bodies, and how they can fulfil the essential health and safety requirements of certain directives. Emphasis will be placed on the prevention of fire and explosion, on the safe use of equipment under pressure, and on the protection of personnel who work with machinery. Additionally considered is how the proper use of adequate procedures available at the time would have prevented three large scale offshore petroleum accidents: the Macondo Deepwater Horizon in the Gulf of Mexico in 2010; the Montara in the Timor Sea in 2009; the Piper Alpha in the North Sea in 1988.

A Novel Methodology for Optimal Design of Compressor Plants Using Probabilistic Plant Design

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Rainer Kurz ◽  
J. Michael Thorp ◽  
Erik G. Zentmyer ◽  
Klaus Brun
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Operating Conditions ◽  
Process Conditions ◽  
Plant Design ◽  
Well Performance ◽  
Worst Case ◽  
Gas Industry ◽  
Machine Performance ◽  
Equipment Sizing

Equipment sizing decisions in the oil and gas industry often have to be made based on incomplete data. Often, the exact process conditions are based on numerous assumptions about well performance, market conditions, environmental conditions, and others. Since the ultimate goal is to meet production commitments, the traditional method of addressing this is to use worst case conditions and often adding margins onto these. This will invariably lead to plants that are oversized, in some instances, by large margins. In reality, the operating conditions are very rarely the assumed worst case conditions, however, they are usually more benign most of the time. Plants designed based on worst case conditions, once in operation, will, therefore, usually not operate under optimum conditions, have reduced flexibility, and therefore cause both higher capital and operating expenses. The authors outline a new probabilistic methodology that provides a framework for more intelligent process-machine designs. A standardized framework using a Monte Carlo simulation and risk analysis is presented that more accurately defines process uncertainty and its impact on machine performance. Case studies are presented that highlight the methodology as applied to critical turbomachinery.

Ready to collaborate? Operator and supply chain under the spotlight

2017 ◽  
Vol 57 (2) ◽  
pp. 498
Author(s):  
Mike Lynn ◽  
Alan Samuel
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Commodity Price ◽  
Capital Projects ◽  
Gas Industry ◽  
New Ways Of Working ◽  
Service Companies ◽  
The North ◽  
The North Sea ◽  
The Uk

In the last 12 months or so, particularly with the drop in oil price, there’s been a lot of speculation about the future of the Australian oil and gas industry. Strenuous efforts are being made to bring down costs, reduce complexity and expedite the completion of major capital projects. Yet with the commodity price looking likely to be subdued for some time, serious questions persist. How can we sustain activity in Australia, secure the investment needed to continue exploration and appraisal drilling, for the next wave of projects? In looking for answers to these challenges, collaboration is a theme that comes up time and time again. But what does it actually mean? What does it look like in practice? Who does it well and how? And which companies are reaping the rewards of great collaboration? To fill this knowledge gap we are launching a survey which will look at many aspects of collaboration in the Australia and compare this with the results of similar surveys conducted in the UK. We will be looking to survey both operators and service companies working in the Australia and find out: What does collaboration mean? What constitutes effective collaboration? How do companies view themselves and each other as collaborators? How does collaboration in Australia compare with companies in the North Sea? We hope a better understanding of collaboration could help companies in Australia continue to improve productivity and efficiency, adopt new ways of working, and truly make the most of Australia’s abundant resources.

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