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.

Breakthrough Cementing Technology for Enhanced Well Integrity in Myanmar Offshore Shallow Gas Well

2021 ◽  
Author(s):  
Yi Li ◽  
Mohammad Solim Ullah ◽  
Wu Chang Ai ◽  
Thirayu Khumtong ◽  
Kantaphon Temaismithi ◽  
...  
Keyword(s):  
Gas Migration ◽  
Negative Effects ◽  
Shallow Gas ◽  
Gas Well ◽  
Lost Circulation ◽  
Security Issues ◽  
Zonal Isolation ◽  
Primary Cementing ◽  
Fit For Purpose

Abstract In Myanmar offshore, a substantially promising gas reservoir was discovered, the objective of primary cementing is to achieve long term zonal isolation, as any gas migration to surface would cause production loss, as well as significant security issues. Remedial cementing work will cause costly non production time, while the result will be compromised. Shallow gas migration, lost circulation and mud removal, all these factors cause undesired negative effects for cementing design, While the objective is to provide a firm barrier and good zonal isolation, this paper will describe in details the cementing challenge, the methodology, and how the slurry parameter was designed and evaluated for a Fit-For-Purpose solution.

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.

Advanced Remedial Hydraulic Isolation by Perforate and Wash Technique

2021 ◽  
Author(s):  
Andrey Yugay ◽  
Hamdi Bouali Daghmouni ◽  
Andrey Nestyagin ◽  
Fouad Abdulsallam ◽  
Annie Morales ◽  
...  
Keyword(s):  
Time Pressure ◽  
Main Role ◽  
Cement Slurry ◽  
Accelerated Corrosion ◽  
Sustained Casing Pressure ◽  
Zonal Isolation ◽  
Cap Rock ◽  
Primary Cementing ◽  
Two Phases ◽  
Casing Pressure

Abstract Well Cementing can be divided into two phases – primary and remedial cementing. Primary cementing may have 3 functions: casing support, zonal isolation and casing protection against corrosion. First two functions are commonly recognized while the third one might be a point of discussion, as the full casing coverage with 100% clean cement is not something common in most of the fields. In fact, poorly cemented areas of the casing may become negatively charged and create a zones of accelerated corrosion rate. This paper is about main role of cementing - zonal isolation. The process of primary cementing assumes that cement slurry is being pumped into the casing and displaced outside. After wait on cement time (WOC) it becomes hard, develops compressive strength and creates impermeable seal that ensures hydraulic isolation. Old and well-known technique, it still remains one of the most challenging rig operations. It is unlikely to find a service company that would guarantee 100% cement displacement behind the casing all the way from top to bottom. Main challenges in this region are quiet common for many other fields – displacement in deviated sections, losses before and during cementing, exposure to pressure during cement settling. In case the main target is not achieved (no hydraulic isolation behind the casing) – we may observe behind casing communications resulting in sustainable pressures in casing-casing annuluses. In this situation the remedial cementing takes place. It's function is to restore isolation so the cement can work as a barrier that seals off the pressure source. Despite of the good number of sealants available on the market (time, pressure, temperature activated) that can be injected from surface to cure this casing-casing pressure, Company prefers not to do so unless there is a proven injectivity capability that would allow for the sealant to reach deep enough, to protect aquifers in case of outer casing corrosion. Otherwise that would be just a ‘masking" the pressure at surface. Therefore in general Company prefers rig intervention to cure the pressure across the cap rock in between the aquifers and the reservoir. Those aquifers are illustrated on the Figure 1 below: More details on Company casing design, cement evaluation issues, sustained casing pressure phenomena and challenges have been mentioned previously [Yugay, 2019].

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.

Measuring complex for monitoring carbon dioxide in air

2021 ◽  
pp. 68-71
Author(s):  
Igor M. Ageev ◽  
Yuri M. Rybin
Keyword(s):  
Carbon Dioxide ◽  
High Selectivity ◽  
Distilled Water ◽  
Measuring Systems ◽  
Advantages And Disadvantages ◽  
Measuring Complex ◽  
Co2 Level ◽  
Carbon Dioxide Co2 ◽  
Term Monitoring

The advantages and disadvantages of infrared and electrochemical gas analyzers for carbon dioxide CO2 are described. The possibility of using conductometric sensors with distilled water for monitoring the CO2 content in the air has been investigated. Two identical measuring systems were manufactured, each containing two open-type conductometric cells, a matching device and a personal computer. With the help of these complexes, experiments were carried out on the simultaneous measurement of the CO2 content in the air in two places (a laboratory room and a building in a forest, located at a distance of 15 km from each other) with deliberately different daily dynamics of the CO2 level change. A special experiment was carried out, which made it possible to obtain an estimate of the inertia of conductometric cells and a conversion factor for the values of CO2 content into standard units of measurement. It is shown that the daily dynamics of changes in the electrical conductivity of distilled water in open cells corresponds to the expected dynamics of changes in the CO2 content in the rooms where the measurements were carried out. The operability of the measuring complex and the possibility of creating on its basis a device for long-term monitoring of the CO2 content in the air mixture of gases has been confirmed. The principal high selectivity of the measuring complex to CO2 in relation to other gases of the atmosphere has been established.

scholarly journals Update on GOSAT TANSO-FTS performance, operations, and data products after more than 6 years in space

2016 ◽  
Vol 9 (6) ◽  
pp. 2445-2461 ◽  
Author(s):  
Akihiko Kuze ◽  
Hiroshi Suto ◽  
Kei Shiomi ◽  
Shuji Kawakami ◽  
Makoto Tanaka ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Near Infrared ◽  
Satellite System ◽  
Fourier Transform Spectrometer ◽  
Infrared Sensor ◽  
Data Set ◽  
Dry Air ◽  
Retrieval Accuracy ◽  
Carbon Dioxide Co2

Abstract. A data set containing more than 6 years (February 2009 to present) of radiance spectra for carbon dioxide (CO2) and methane (CH4) observations has been acquired by the Greenhouse gases Observing SATellite (GOSAT, available at http://data.gosat.nies.go.jp/GosatUserInterfaceGateway/guig/GuigPage/open.do), nicknamed “Ibuki”, Thermal And Near infrared Sensor for carbon Observation Fourier Transform Spectrometer (TANSO-FTS). This paper provides updates on the performance of the satellite and TANSO-FTS sensor and describes important changes to the data product, which has recently been made available to users. With these changes the typical accuracy of retrieved column-averaged dry air mole fractions of CO2 and CH4 (XCO2 and XCH4, respectively) are 2 ppm or 0.5 % and 13 ppb or 0.7 %, respectively. Three major anomalies of the satellite system affecting TANSO-FTS are reported: a failure of one of the two solar paddles in May 2014, a switch to the secondary pointing system in January 2015, and most recently a cryocooler shutdown and restart in August 2015. The Level 1A (L1A) (raw interferogram) and the Level 1B (L1B) (radiance spectra) of version V201 described here have long-term uniform quality and provide consistent retrieval accuracy even after the satellite system anomalies. In addition, we discuss the unique observation abilities of GOSAT made possible by an agile pointing mechanism, which allows for optimization of global sampling patterns.

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.

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%.

Prevention of Historically Challenging Sustained Casing Pressure from Shallow Gas Through Re-Engineered Cement Design and Execution Methodology

2021 ◽  
Author(s):  
Farah Shakina Ezani ◽  
Myat Thuzar ◽  
Avinash Kishore Kumar ◽  
Chee Hen Lau
Keyword(s):  
Mitigation Measures ◽  
Design Parameters ◽  
Two Stage ◽  
Shallow Gas ◽  
Second Stage ◽  
The Past ◽  
Sustained Casing Pressure ◽  
Dual Stage ◽  
Casing Pressure ◽  
Selection Of

Abstract Sustained casing pressure (SCP) is a very costly event for any operator either at production phase or at the end of a well’s lifecycle. SCP is a result of incomplete hydraulic isolation across hydrocarbon bearing zone. In one of the gas fields in Malaysia, notoriously known for shallow gas hazard, drilled development wells which have reportedly been suffering SCP. In the past, various improvements in cement slurry design and placement methods were deployed in order to provide complete zonal isolation, especially at the shallow gas sand, yet SCP issue was encountered occasionally. In the current development campaign, different strategy to providing annulus sealing was adopted. This paper discusses proactive steps taken in the slurry design, fit together with the dual stage cementing approach, as a primary means of placing cement above the shallow hazard interval. During the design phase, essential key parameters that would lead to successful placement of cement in the annulus as well as unique slurry design that suits for two stage cementing methods were studied. Risk involved in first stage cementing is one of the most important steps that should be analyzed in detail and put mitigation measures in place to ensure the second stage cement job can be performed as planned. In addition to the slurry properties, such as fluid-loss value, gas-tightness, etc., thickening time and top of cement (TOC) of the lead slurry in the first stage cement job has become enormously critical in designing dual stage cementing job in order to assure cement ports in the stage collar are not covered with hard cement forcing the termination of second stage job prematurely. Besides cementing design, careful selection of the stage collar location and casing annulus packer in the string is also of significant importance in leading to successful two stage cement job. Two development wells with above approached has been delivered and no sustained casing pressure has been experienced. This proactive approach to use two stage cementing as primary plan has proven to successfully eliminate the risk of SCP, which was a frequent struggle in their sister wells drilled with primary cementing in the past in the same field. The risk analysis combined with careful considerations of critical cementing design parameters and selection of stage tool location have become a novel approach to combat against SCP in this gas field.

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.

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