Novel collaborative P&A campaign using inflatable packers and bismuth alloy plugs

2021 ◽  
Vol 61 (2) ◽  
pp. 536
Author(s):  
Adam Bensaied ◽  
George Farag ◽  
Jeff Fulks
Keyword(s):  
Gas Flow ◽  
Cost Savings ◽  
Significant Cost ◽  
North West ◽  
Sustained Casing Pressure ◽  
Bismuth Alloy ◽  
Casing Pressure ◽  
Cement Plug ◽  
Lengthy Process

Chevron Australia, a leading O&G operator on the Australian North West Shelf, executed a plug and abandonment (P&A) campaign where 34 wells (19 offshore and 15 onshore) incorporated a novel bismuth alloy barrier system to the traditional cement plug. The challenge of isolating shallow gaseous zones that cause sustained casing pressure and free gas flow to surface behind the production casing was overcome by this new innovative use of collaborative technologies to provide an optimised P&A solution. The offshore/onshore P&A campaign was completed successfully with significant cost savings, eliminating the lengthy process of section milling more than 100ft of casing on each well, providing a long-term bismuth alloy barrier in the well and eliminating the potential need to reenter the well later due to a leaking cement plug.

A Breakthrough Approach to Solve Shallow Gas Hazards in Corrosive Carbon Dioxide Wells

2021 ◽  
Author(s):  
Yi Li ◽  
Solim Ullah Mohammad ◽  
Wu chang Ai ◽  
Avinash Kishore Kumar ◽  
Lau Chee Hen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Flow ◽  
Shallow Gas ◽  
Security Issues ◽  
Sustained Casing Pressure ◽  
Zonal Isolation ◽  
Primary Cementing ◽  
Carbon Dioxide Co2 ◽  
Casing Pressure

Abstract In offshore Malaysia field, several development wells were drilled and cemented in 2019. The presence of shallow gas zone directly below the surface casing shoe posed a significant challenge to isolate shallow gas flow. A High presence of carbon dioxide (CO2) also increased the complexity of the cementing jobs by potentially corroding the set cement sheath. Wells with sustained casing pressure due to poor cementing jobs would causelosses to hydrocarbon reserves, while polluting aquifers with hydrocarbon and well security issues. It was crucial to prevent remedial cementing work, due to unnecessary and costly non-productive time. The objective of primary cementing is to achieve long term zonal isolation across the gas reservoir. A bespoke engineered cementing solution was successfully developed in order to provide a solution to assure long term zonal isolation for shallow gas flow. This paper will describe in detail about the cementing method, how it fits the well situation, the methodology in the slurry design, and thevalidation process in the lab with a novel, uncommon method in the industry, capped off by the post-cementing results analysis. This technology was proven as a solution for shallow gas well cementing and long-term zonal isolation, which is a great referencefor the cementing industry.

Study of Ultrasonic Logs and Seepage Potential on Sandwich Sections Retrieved from a North Sea Production Well

2021 ◽  
pp. 1-15
Author(s):  
Hans Joakim Skadsem ◽  
Dave Gardner ◽  
Katherine Beltrán Jiménez ◽  
Amit Govil ◽  
Guillermo Obando Palacio ◽  
...  
Keyword(s):  
Gas Flow ◽  
Fluid Migration ◽  
Production Well ◽  
Offshore Production ◽  
Extensive Test ◽  
Sustained Casing Pressure ◽  
Zonal Isolation ◽  
Seepage Characteristics ◽  
Casing Pressure ◽  
Well Cement

Summary Important functions of well cement are to provide zonal isolation behind casing strings and to mechanically support and protect the casing. Experience suggests that many wells develop integrity problems related to fluid migration or loss of zonal isolation, which often manifest themselves in sustained casing pressure (SCP) or surface casing vent flows. Because the characteristic sizes of realistic migration paths are typically only on the order of tens of micrometers, detecting, diagnosing, and eventually treating migration paths remain challenging problems for the industry. As part of the recent abandonment operation of an offshore production well, sandwich joints comprising production casing, annulus cement, and intermediate casing were cut and retrieved to surface. Two of these joints were subjected to an extensive test campaign, including surface relogging, chemical analyses, and seepage testing, to better understand the ultrasonic-log response and its potential connection to rates of fluid migration. One of the joints contained an apparently well-defined top of cement (TOC) with settled barite on top. Although the settled material initially provided a complete seal against gas flow, the sealing capability was irreversibly lost as part of subsequent testing. The two joints have effective microannuli sizes in the range of tens of micrometers, in agreement with previous reports on SCP buildup in wells. On a local scale, however, we observed significant variations in cement quality from both the log results and the seepage testing. Further, we found qualitatively very good correlations between seepage-test results and the log results for the bond between cement and casings. The best bonded cement was found directly above a production casing collar, where a short segment of well-bonded cement prevented measurable steady-state seepage of nitrogen. Additional tests involving internal pressurization of the production casing suggested that certain annular-seepage characteristics are well-described by an effective microannulus at the cement/casing interfaces. We consider the two sandwich joints to be highly representative and relevant for similar mature wells that are to be abandoned.

Successful Remediation of Sustained Casing Pressures in Gas Cap Injector Wells with the Use of Flexible and Self Healing System

2021 ◽  
Author(s):  
Bipin Jain ◽  
Abhijeet Tambe ◽  
Dylan Waugh ◽  
Moises MunozRivera ◽  
Rianne Campbell
Keyword(s):  
Self Healing ◽  
Injection Wells ◽  
Coiled Tubing ◽  
Cement System ◽  
Sustained Casing Pressure ◽  
Casing Pressure ◽  
New Generation ◽  
Prudhoe Bay ◽  
Production Tubing

Abstract Several injection wells in Prudhoe Bay, Alaska exhibit sustained casing pressure (SCP) between the production tubing and the inner casing. The diagnostics on these wells have shown communication due to issues with casing leaks. Conventional cement systems have historically been used in coiled-tubing-delivered squeeze jobs to repair the leaks. However, even when these squeeze jobs are executed successfully, there is no guarantee in the short or long term that the annular communication is repaired. Many of these injector wells develop SCP in the range of 300-400 psi post-repair. It has been observed that the SCP development can reoccur immediately after annulus communication repair, or months to years after an injector well is put back on injection. Once SCP is developed the well cannot be operated further. A new generation of cement system was used to overcome the remedial challenge presented in these injector wells. This document provides the successful application of a specialized adaptive cement system conveyed to the problematic zone with the advantage of using coiled tubing equipment for optimum delivery of the remedial treatment.

Digitalisation as a critical tool in resource asset valuations, acquisitions and dispositions

2019 ◽  
Vol 59 (2) ◽  
pp. 609
Author(s):  
Douglas W. Hollett ◽  
Craig N. Phasey
Keyword(s):  
Portfolio Management ◽  
Deep Understanding ◽  
Cost Savings ◽  
Asset Valuation ◽  
Significant Cost ◽  
New Approach ◽  
Digital Twins ◽  
And Control ◽  
A Company

Digital twins and digital ‘solutions’ have become increasingly common in recent years, as companies recognise the benefit of greater visibility and control into their operations. When built and implemented properly, a digital twin (DT) offers the potential for significant cost savings, coupled with attractive add-on value in safety, operational integrity and predictive maintenance, all of which can also result in increased production. DTs are also critical for effective portfolio management, in allowing a full understanding of asset or field value, upside, and long-term potential. By identifying areas for optimisation, a DT can help the operator prioritise investment, and accurately understand which assets to keep or monetise. Through building DTs for operating properties, Nova Systems and PTC have gained a deep understanding of the upside potential inherent in the technology. This also means that DT technology can be invaluable in asset acquisitions. During merger and acquisition (M&A) analysis, a company typically looks for technical, operational and financial leverage which can unlock potential not seen by the current owner. These can be commercial (commodity contract, price deck and agreements), technical (e.g. engineering approach and models, and subsurface), operating synergies (common services, facilities and duplication) and digital solutions. While most companies utilise traditional and tested approaches to asset valuation, new digital solutions offer the opportunity for break-out higher valuations which can drive an entirely new approach to M&A growth. In today’s competitive marketplace, the company with an innovative digital solutions skillset will have the advantage.

Cement Plug Sealing Studies of Silica Cement Systems

2019 ◽  
Author(s):  
Anisa Noor Corina ◽  
Nils van der Tuuk Opedal ◽  
Torbjørn Vrålstad ◽  
Sigbjørn Sangesland
Keyword(s):  
Gas Flow ◽  
Curing Temperature ◽  
Small Scale ◽  
The Past ◽  
Laboratory Setup ◽  
Gas Leak ◽  
Zonal Isolation ◽  
Cement Mixture ◽  
Cement Plug

Abstract A cement plug is widely applied for permanent abandonment phase to provide long-term zonal isolation against fluid flow. Maintaining cement plug integrity is a challenging task, and loss in cement sealing poses risks to the surrounding environment and surface safety. It is well-known that the cement performance is affected by cement material and downhole conditions. Nevertheless, investigations linking these influencing factors with the sealing of cement plugs are still limited, especially with the lack of proper equipment in the past. In the present work, a small-scale laboratory setup has been constructed to test the sealing ability of a cement plug. It has unique features that can simulate plugging operations at the downhole conditions and preserve the cement curing condition. By testing using this setup, it is possible to measure the minimum differential pressure required for gas to flow across the cement plug and the gas leak rate. The silica cement mixture was selected as the plug material, prepared using silica flour. Investigation of silica cement under the influence of expanding agent additive and various curing temperature was carried out. It was found that adding an expanding agent improved the sealing of cement plugs. Moreover, samples cured at a high temperature were less resistant to gas flow with the leak path observed at the cement/steel interface, indicating debonding.

Potentials of Nano-Designed Plugs: Implications for Short and Long Term Well Integrity

2019 ◽  
Author(s):  
Raymos Kimanzi ◽  
Harshkumar Patel ◽  
Mahmoud Khalifeh ◽  
Saeed Salehi ◽  
Catalin Teodoriu
Keyword(s):  
Compressive Strength ◽  
Oil And Gas ◽  
Strength Development ◽  
Cement Slurry ◽  
Preparation Conditions ◽  
Cement System ◽  
Sustained Casing Pressure ◽  
Short And Long Term ◽  
Casing Pressure

Abstract Cement plugs are designed to protect the integrity of oil and gas wells by mitigating movement of formation fluids and leaks. A failure of the cement sheath can result in the loss of zonal isolation, which can lead to sustained casing pressure. In this study, nanosynthetic graphite with designed expansive properties has been introduced to fresh cement slurry. The expansive properties of nanosynthetic graphite were achieved by controlling the preparation conditions. The material was made from synthetic graphite and has a surface area ranging from 325–375 m2/gram. Several tests including compressive strength, rheology, and thickening time were performed. An addition of 1% nanosynthetic graphite with appropriate reactivity was sufficient to maintain expansion in the cement system, leading to an early compressive strength development. It has excellent thermal and electrical conductivity and can be used to design a cement system with short and long-term integrity. Rheology and thickening time tests confirmed its pumpability. Controlling the concentration of the additive is a promising method that can be used to mitigate gas migration in gas bearing and shallow gas formations.

Use of Novel Self-Healing Materials to Control Sustained Casing Pressure and Prevent Long Term Environmental Impact

2015 ◽  
Author(s):  
Mohammad Arif Khattak ◽  
Bipin Jain ◽  
Sultan Al Kalbani ◽  
Junaid Ahmed ◽  
Agung Arya Afrianto ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Self Healing ◽  
Sustained Casing Pressure ◽  
Casing Pressure

An Integrated Scale Protection Package for Offshore Fractured Wells Under Designed Shut-In Extension

2021 ◽  
Author(s):  
Zhiwei David Yue ◽  
Andrew Slocum ◽  
Xiaohong Lucy Tian ◽  
Linping Ke ◽  
Megan Westerman ◽  
...  
Keyword(s):  
Cost Savings ◽  
Control Program ◽  
Extended Period ◽  
Formation Water ◽  
Scale Inhibitor ◽  
Significant Cost ◽  
Scale Inhibition ◽  
Reservoir Conditions ◽  
Inhibition Performance

Abstract After fracturing, it is common practice to leave offshore wells shut-in from days to weeks for operational purposes. During the recent historic decline of demand for global crude, a trend has been witnessed to shut in even newly fractured wells under design for an extended period. The cause of these extended shut-ins can be attributed to various factors including operational logistics as well as economic factors. The shut-in extension brings some unique scaling challenges for well designs. In this paper, an integrated scale inhibitor (SI)/fracturing fluid package is presented with detailed laboratory prerequisites data to validate its efficacy for long-term scale protection during the extended shut-in. Utilizing seawater in offshore fracturing can provide significant cost savings to an operation. Unfortunately, in regions with barium-rich formations, the use of seawater brings tremendous barite scaling risk. In order to solve this challenge, the investigation focused on the selection of the most effective inhibitors for long-term barite inhibition under the simulated reservoir conditions. Along with the scale inhibitor selection, the crosslinked gel had to be carefully optimized to eliminate any potential negative interference the gel additives could impart to the performance of the inhibitor. Furthermore, the inhibitor was tested in the crosslinking system to meet optimum rheology requirements. Utilizing the broken gel containing the designed inhibitor package, barite precipitation could be prevented for months under the simulated testing conditions. Due to high levels of sulfate from seawater and the barium originating from the formation, barite scale formed immediately upon mixing of the two types of water in absence of the appropriate scale inhibitors. Solid scale products featuring slow releasing of the inhibitor ingredients was proven insufficient for this application. With extensive laboratory screening, the candidate chemistry demonstrated great brine-calcium tolerance, superior scale inhibition performance for both sulfate and carbonate scales, and the minimum interferences for the crosslinking engineering to meet necessary proppant carrying capacity. To mimic the gel-breaking process and heterogeneous bleeding from the formation water, the inhibitor was crosslinked with the gel at various loading rates (1 gpt to 10 gpt) and broken at the elevated reservoir temperature, then mixed with the different ratios of the formation water. Reliable scale inhibition performance was achieved for an extended period of time for up to six weeks. Incorporating SI into the fracturing stimulation package is a convenient method for operators to include a scale-control program into well-defined fracturing designs with minimal adjustment and also add significant cost-saving for offshore logistics and rig time (Fitzgerald, et al., 2008). The scale inhibitor product presented in this paper shows a superior solution to protect assets from scale deposition for an extended shut-in period.

CURRENT STATE AND DEVELOPMENT PERSPECTIVES OF THE CASPIAN SPRAT FISHERIES

2018 ◽  
pp. 69-75
Author(s):  
Tatiana Vasilievna Pomogaeva ◽  
Aliya Ahmetovna Aseinova ◽  
Yuriy Aleksandrovich Paritskiy ◽  
Vjacheslav Petrovich Razinkov
Keyword(s):  
Food Item ◽  
Growth Potential ◽  
North West ◽  
Marine Fishery ◽  
The North ◽  
Current State ◽  
West Part ◽  
Eggs And Larvae ◽  
Intensive Growth

The article presents annual statistical data of the Caspian Research Institute of Fishery. There has been kept track of the long term dynamics of the stocks of three species of Caspian sprat (anchovy, big-eyed kilka, sprat) and investigated a process of substituting a food item of sprats Eurytemora grimmi to a small-celled copepod species Acartia tonsa Dana. According to the research results, there has been determined growth potential of stocks of each species. Ctenophoran-Mnemiopsis has an adverse effect on sprat population by eating fish eggs and larvae. Ctenophoram - Mnemiopsis is a nutritional competitor to the full-grown fishes. The article gives recommendations on reclamation of stocks of the most perspective species - common sprat, whose biological characteristics helped not to suffer during Ctenophoram outburst and to increase its population during change of the main food item. Hydroacoustic survey data prove the intensive growth of common sprat biomass in the north-west part of the Middle Caspian. According to the results of the research it may be concluded that to realize the volumes of recommended sprat catch it is necessary to organize the marine fishery of common sprat at the Russian Middle Caspian shelf.

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