scholarly journals Numerical Modeling of Radial Fracturing of Cement Sheath Caused by Pressure Tests

2019 ◽  
Author(s):  
Sohrab Gheibi ◽  
Sigbjørn Sangesland ◽  
Torbjørn Vrålstad
Keyword(s):  
Numerical Code ◽  
Hydrocarbon Production ◽  
Well Integrity ◽  
Pressure Tests ◽  
Pressure Test ◽  
Zonal Isolation ◽  
Tensile Fractures ◽  
Fracture Opening ◽  
Cement Sheath ◽  
Geological Co2 Sequestration

Abstract To achieve an acceptable level of zonal isolation, well integrity should be guaranteed in hydrocarbon production and geological CO2 sequestration. Well pressure test can cause different types of failures in the well system leading to leakages through these failures. Laboratory evidences have revealed that occurrence of radial tensile fractures is likely during pressure tests. In this paper, we use a numerical code call MDEM which was formulated based on discrete element method. The code can model discontinuum feature of fractures. A model of a lab-sized pressure test was built and compared to an experiment previously published. The model was tested under different confinement levels and effect of the tensile strength of rock on the radial fracture was investigated at the same lab-scale. Fracture opening profiles are also presented showing the leakage potential of these fractures under different pressure level.

Application of Resin-Cement Blend to Prevent Pressure Build-Up in Casing to Casing Annulus CCA: A Novel Approach to Improve Well Integrity

2021 ◽  
Author(s):  
Wajid Ali ◽  
Freddy Jose Mata ◽  
Ahmed Atef Hashmi ◽  
Abdullah Saleh Al-Yami
Keyword(s):  
High Pressure ◽  
Shear Bond Strength ◽  
Resin Cement ◽  
Cement Slurry ◽  
Well Integrity ◽  
Cement System ◽  
Zonal Isolation ◽  
Primary Cementing ◽  
Cement Sheath

Abstract Assurance of well integrity is critical and important throughout the entire well's life cycle. Pressure build-up between cemented casings annuli has been a major challenge all around the world. Cement is the main element that provides isolation and protection for the well. The cause for pressure build-up in most cases is a compromise of cement sheath integrity that allows fluids to migrate through micro-channels from the formation all the way to the surface. These problems prompt cementing technologists to explore new cementing solutions, to achieve reliable long-term zonal isolation in these extreme conditions by elevating shear bond strength along-with minimal shrinkage. The resin-cement system can be regarded as a novel technology to assure long term zonal isolation. This paper presents case histories to support the efficiency and reliability of the resin-cement system to avoid casing to casing annulus (CCA) pressure build-up. This paper presents lab testing and application of the resin-cement system, where potential high-pressure influx was expected across a water-bearing formation. The resin-cement system was designed to be placed as a tail slurry to provide a better set of mechanical properties in comparison to a conventional slurry. The combined mixture of resin and cement slurry provided all the necessary properties of the desired product. The slurry was batch-mixed to ensure the homogeneity of resin-cement slurry mixture. The cement treatment was performed as designed and met all zonal isolation objectives. Resin-cement’s increased compressive strength, ductility, and enhanced shear bond strength helped to provide a dependable barrier that would help prevent future sustained casing pressure (SCP). The producing performance of a well depends in great part on a good primary cementing job. The success of achieving zonal isolation, which is the main objective of cementing, is mainly attributed to the cement design. The resin-cement system is evolving as a new solution within the industry, replacing conventional cement in many crucial primary cementing applications. This paper highlights the necessary laboratory testing, field execution procedures, and treatment evaluation methods so that this technology can be a key resource for such operations in the future. The paper describes the process used to design the resin-cement system and how its application was significant to the success of the jobs. By keeping adequate strength and flexibility, this new cement system mitigates the risk of cement sheath failure throughout the life of well. It provides a long-term well integrity solution for any well exposed to a high-pressure environment.

Mud-Removal Efficiency Boost by Engineered Scrubbing Spacer in Cementing Operations at Caspian Sea

2021 ◽  
Author(s):  
Amanmammet Bugrayev ◽  
Ravindra Kumar Singh ◽  
Svetlana Nafikova ◽  
Ilshat Akhmetzianov ◽  
Guvanch Gurbanov ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Successful Implementation ◽  
Gas Migration ◽  
Negative Consequences ◽  
Well Integrity ◽  
Annular Gap ◽  
Challenging Environment ◽  
Zonal Isolation ◽  
Cement Sheath

Abstract Long-term well integrity and zonal isolation are the ultimate objectives for cementing in the well construction process. Effective mud removal plays an essential role in obtaining competent zonal isolation and hence should not be overlooked and underestimated. The negative consequences of poor mud removal can lead to microannulus, channeling, or gas migration, which might require costly time-consuming remediation. The conventional approach of optimizing spacers based on chemical interactions with the mud layer does not always yield desired results and, thus, demanding further improvement. In this paper we discuss the approach taken to boost the mud removal efficiency by implementing an innovative engineered scrubbing spacer containing fibers in a challenging environment, resulting in notable improvement in long-term cement sheath integrity. The engineered scrubbing fibers were thoroughly tested in the laboratory to ensure spacer stability and efficiency. The new spacer with an additional scrubbing capability was introduced to one of the major operators on the Caspian shelf and after successful implementation, it has now been used on more than 20 cementing operations. Scrubbing fibers concentration was optimized through thorough laboratory testing covering flowability, dispersibility, and mud removal efficiency; later, it was applied on most of the cement operations, including 4½-in. liners characterized by a very narrow annular gap across the hanger sections. Cement evaluation log results from those cementing operations demonstrated an improvement in mud removal efficiency, suggesting no issues associated with microannulus, channeling, or gas migration, thus confirming the effectiveness of the newly implemented engineered scrubbing spacer. The typical challenges associated with meeting the zonal isolation requirement on one of the offshore fields of the Caspian shelf, and the success of the approach taken to overcome those challenges by implementing the new engineered scrubbing spacer are discussed. The comparison of cement bond evaluation log results of the jobs where conventional spacer systems were used vs. those where the spacer with scrubbing capability was used are also presented, demonstrating the clear difference and improvement.

Achieving Long Term Well Integrity: An Engineered Solution for Production Casing in a Deepwater Environment

2014 ◽  
Author(s):  
V.. Reveth ◽  
R.. Giron Rojas ◽  
N.. Gupta ◽  
E.. Gonzaga
Keyword(s):  
Mechanical Performance ◽  
Rock Properties ◽  
Cement Matrix ◽  
Self Healing ◽  
Well Integrity ◽  
Zonal Isolation ◽  
Cement Sheath ◽  
The Impact ◽  
Fluid Pathway

Abstract In a deepwater environment, any remedial operation has a high impact on the overall costs during the life of the wells. The zonal isolation can be compromised due to the exposure of the well's main components (casing and cement) to the changes in the stress conditions. The changes in wellbore conditions can occur during the drilling, production, intervention, and decommissioning stages. Typically, conditions such as fluid pathway and high formation pressure are sufficient to lose zonal isolation. The fluid pathway can be a fissure, an induced crack in the cement sheath, a mud channel, a micro-microannulus, or changes in the cement matrix permeability. As a result of the oil industry technology developments, progresses, the advanced stress-modelling software and the availability of cement and rock properties property data have enabled to an improved understanding of the cement behavior under stress. Prevention of the loss of the hydraulic isolation provided by the primary cementing in the annulus can be assessed by predicting the mechanical failure of the cement sheath. Formation geo-mechanics is one of the main factors that help in designing a robust cement system for changing stresses. Furthermore, the consequence result of the cement sheath failure can be mitigated by the placement of placing a self-healing cement (SHC) system to maintain long-term zonal isolation. An interdisciplinary approach can be used to determine the following: Understand the impact of the well plan, and fluid densities on well integrity, in addition to cementing best practices.Characterize typical deepwater field formations, and establish limits for geo-mechanical values of each layer.Identify critical factors and focus on the pay zones.Understand potential issues and communication between the pay zones and the aquifers that are already previously confirmed.Determine risk of zonal communication assessment, mitigation, and prevention measurement implementations Once the formation data is validated by the operator, the life cycle of the well is simulated and the risk of zonal isolation can be evaluated. The results of this assessment can help the operator choose between to take the approach of mitigation, prevention, or a combination of both. The objective is to place a robust cement sheath with advanced mechanical performance in the pay zones that can resist the failures due to changing stresses during the well testing and production. This paper uses presents examples from a deepwater development field to show how cement systems with advanced mechanical properties counter the critical stresses during the lifecycle of a well and maintain zonal isolation.

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.

A Canadian Operator Based Framework for Pipeline Pressure Tests: Lessons Learned

2018 ◽  
Author(s):  
Nicole-Lee M. Robertson ◽  
Bob Campbell
Keyword(s):  
Quality Control ◽  
Lessons Learned ◽  
Internal Process ◽  
Road Map ◽  
Pressure Tests ◽  
Pressure Test ◽  
Pipeline Pressure ◽  
Increase Efficiency

Commissioning pressure tests are a critical life-of-asset record. Successfully achieving an acceptable pressure test can be challenging both at an execution and documentation perspective. This paper aims to assist in streamlining the approach to pipeline commissioning pressure tests between operators to increase efficiency and drive consistency across the pipeline industry. Key lessons learned from the planning stages through to the quality control turnover are highlighted. Lessons learned, respective to pressure tests, include: road map of Canadian regulations, tabulated equipment requirements, suggested instrumentation setup, template checklist for test plans, outlined company to contractor responsibilities, as well as a proposed internal process to manage and accept completed tests.

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%.

Additives to Enhance Cement Sheath Durability

2019 ◽  
Author(s):  
Maryam Tabatabaei ◽  
Arash Dahi Taleghani ◽  
Nasim Alem
Keyword(s):  
Shear Failure ◽  
Oil And Gas ◽  
Pressure Fluctuations ◽  
High Strength ◽  
Graphite Nanoplatelets ◽  
Gas Well ◽  
Micro Cracks ◽  
Zonal Isolation ◽  
Cement Sheath ◽  
Agglomeration Of Nanoparticles

Abstract The primary goal of the oil and gas well cementing is zonal isolation. During the production life of a well, the cement experiences various severe conditions affecting its permeability. These conditions include cracking, debonding, and shear failure which can be worsened by pressure fluctuations during hydraulic fracturing operations. Any of these conditions by forming micro-cracks within the cement or micro-annuli at the casing/cement or cement/rock interfaces create cement permeabilities far beyond the intrinsic permeability of the intact cement sheath. Recently, some studies have been devoted to improving the overall mechanical behavior of the cement by adding carbon nanotubes and carbon nano-fibers. Although these nano-additives offer considerably high strength and modulus, the high costs of these materials persuade us to find alternatives at relatively low costs, such as, graphite nanoplatelets (GNPs). Our preliminary laboratory studies show the effectiveness of GNPs in the enhancement of durability characteristics of the prepared nanocomposite cement paste by improving its compressive strength, ductility and toughness resistance. Considering the importance of dispersion of nanoadditives within the cementitious matrix, we physically or chemically manipulate the surface properties of GNPs to prevent the agglomeration of nanoparticles.

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