Risk and Remediation of Irreducible Casing Pressure at Petroleum Wells

2014 ◽  
pp. 155-180 ◽  
Author(s):  
Andrew K. Wojtanowicz
Keyword(s):  
Oil Well ◽  
Gas Migration ◽  
Excessive Pressure ◽  
Wet Gas ◽  
Regulatory Approach ◽  
Sustained Casing Pressure ◽  
Small Cracks ◽  
Petroleum Wells ◽  
Casing Pressure ◽  
Well Cement

Oil well cement problems such as small cracks or channels may result in gas migration and lead to irreducible pressure at the casing head. Irreducible casing pressure also termed, Sustained Casing Pressure (SCP) is hazardous for a safe operation and the affected wells cannot be terminated without remedial operations. It is believed that even very small leaks might lead to continuous emissions of gas to the atmosphere. In the chapter, the author describes physical mechanisms of irreducible casing pressure and qualifies the associated risk by showing statistical data from the Gulf of Mexico and discussing the regulatory approach. This chapter also introduces a new approach to evaluate risk of casing pressure by computing a probable rate of atmospheric emissions from wells with failed casing heads resulting from excessive pressure. Also presented is a new method for assessing potential for self-plugging of such wells flowing wet gas as the gas migration channels could be plugged off by the condensate.

Laboratory Visualization of Gravity Fluid Displacement in Well Annulus Affected by Sustained Casing Pressure

2015 ◽  
Author(s):  
Efecan Demirci ◽  
Andrew K. Wojtanowicz
Keyword(s):  
Injection Rate ◽  
Fluid Displacement ◽  
Two Fluids ◽  
Gas Leak ◽  
Displacement Experiments ◽  
Sustained Casing Pressure ◽  
Petroleum Wells ◽  
Casing Pressure ◽  
Well Cement ◽  
Synthetic Clay

Sustained Casing Pressure (SCP) in petroleum wells poses environmental risk and needs to be removed using either downhole intervention or annular intervention methods. The latter method involves displacing the annular fluid above the top of the gas-leaking well cement with a heavy fluid to increase the hydrostatic pressure and stop the gas leak. Past field applications of the method failed — most likely due to incompatibility of the two fluids. In this study, a see-through scaled-down hydraulic analog of the well’s annulus was designed and used for video-taped displacement experiments with clear synthetic-clay muds and heavy (kill) fluids. The results show that only immiscible hydrophobic kill fluids provide effective displacement. The study demonstrates importance of controlled injection of the kill fluid to set out efficient buoyant settling and prevent initial dispersion. A side- (versus top-) injection geometry and the injection rate data are analyzed to develop empirical correlation of maximum injection rate for a given properties of the two fluids.

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.

Enhanced Cement Composition for Preventing Annular Gas Migration

2019 ◽  
Author(s):  
George Kwatia ◽  
Mustafa Al Ramadan ◽  
Saeed Salehi ◽  
Catalin Teodoriu
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Oil Well ◽  
Gas Migration ◽  
Cement Slurry ◽  
Gas Industry ◽  
Well Integrity ◽  
Transit Times ◽  
Well Cement ◽  
Gas Tight

Abstract Cementing operations in deepwater exhibit many challenges worldwide due to shallow flows. Cement sheath integrity and durability play key roles in the oil and gas industry, particularly during drilling and completion stages. Cement sealability serves in maintaining the well integrity by preventing fluid migration to surface and adjacent formations. Failure of cement to seal the annulus can lead to serious dilemmas that may result in loss of well integrity. Gas migration through cemented annulus has been a major issue in the oil and gas industry for decades. Anti-gas migration additives are usually mixed with the cement slurry to combat and prevent gas migration. In fact, these additives enhance and improve the cement sealability, bonding, and serve in preventing microannuli evolution. Cement sealability can be assessed and evaluated by their ability to seal and prevent any leakage through and around the cemented annulus. Few laboratory studies have been conducted to evaluate the sealability of oil well cement. In this study, a setup was built to simulate the gas migration through and around the cement. A series of experiments were conducted on these setups to examine the cement sealability of neat Class H cement and also to evaluate the effect of anti-gas migration additives on the cement sealability. Different additives were used in this setup such as microsilica, fly ash, nanomaterials and latex. Experiments conducted in this work revealed that the cement (without anti-gas migration additive) lack the ability to seal the annulus. Cement slurries prepared with latex improved the cement sealability and mitigated gas migration for a longer time compared to the other slurries. The cement slurry formulated with a commercial additive completely prevented gas migration and proved to be a gas tight. Also, it was found that slurries with short gas transit times have a decent potential to mitigate gas migration, and this depends on the additives used to prepare the cement slurry.

Gas Migration Prevention Using Hydroxypropylmethylcellulose as a Multifunctional Additive in Oil Well Cement Slurry

2013 ◽  
Author(s):  
Ghulam Abbas ◽  
Sonny Irawan ◽  
Sandeep Kumar ◽  
Muhammad Nisar Khan ◽  
Shuaib Memon
Keyword(s):  
Oil Well ◽  
Gas Migration ◽  
Cement Slurry ◽  
Multifunctional Additive ◽  
Oil Well Cement ◽  
Well Cement

scholarly journals Reduction of fluid migration in well cement slurry using nanoparticles

2020 ◽  
Vol 75 ◽  
pp. 67
Author(s):  
Mahmoud Bayanak ◽  
Soroush Zarinabadi ◽  
Khalil Shahbazi ◽  
Alireza Azimi
Keyword(s):  
Fluid Migration ◽  
Oil Well ◽  
Gas Migration ◽  
Test Results ◽  
Cement Slurry ◽  
Negative Effects ◽  
Transient Time ◽  
Well Completion ◽  
Nanosilica Particles ◽  
Well Cement

One of the main problems during oil well completion and cementing operation is fluid migration through cement bulk or behind the cemented casing. Slurry composition and characteristic have been focused and improved in last decades to mitigate gas migration and, recently, aspects such as using nanotechnology have been investigated to amend the conditions. In this research, two moderate base slurries with 95 and 120 Pound per Cubic Feet (PCF) densities containing different percentages of nanosilica have been examined using a perfect test package. The results of Fluid Migration Analyzer (FMA) demonstrated that using correct percentage of nanosilica particles modified rheological behavior of the slurries and decreased fluid migration volume. Moreover, adding nanoparticles did not have any negative effects on any conventional parameters. However, static gel strength analyzer showed significant transient time reduction which is an important key in cement setting profile. Triaxial test results together with Mohr circles analyzing presented considerable progress in cement stability and compressive strength.

Wellbore Integrity and CO2 Sequestration Using Polyaramide Vesicles

2021 ◽  
Author(s):  
Elizabeth Q. Contreras
Keyword(s):  
Oil Well ◽  
Gravimetric Analysis ◽  
Self Healing ◽  
Gas Migration ◽  
Reactive Polymer ◽  
Wellbore Integrity ◽  
Polymer Vesicles ◽  
Oil Well Cement ◽  
Well Cement ◽  
Oilfield Equipment

Abstract A new cementing additive is chemically engineered to react with formation fluids that act antagonistically towards cement. Engineered polymer capsules house encapsulants to react with antagonistic gases downhole like CO2 to form a more benign and beneficial material. Embedded in cement, the polymer capsules with semi-permeable shells allow fluids to permeate and react with encapsulants to produce beneficial byproducts, such as calcite and water from CO2. Reactivity between the encapsulant and antagonist gas CO2 is demonstrated using thermal gravimetric analysis (TGA) and other tests from oilfield equipment. When cement fails, casing-in-casing events, or CCA, causes antagonistic gases like CO2 to migrate to the surface. Embedded in the cement for such moments such as cement failure, additives housed within polyaramide vesicles chemically and physically intersect CO2 from gas migration events. The shape of the polyaramide additive is unique and versatile. Furthermore, because the material is polymeric, it imparts beneficial mechanical properties like elasticity to cement. A vesicle in form, this polymer allows the manufacturing of new cement additives for applications such as increasing the integrity and sustainability of oil well cement. Data also shows production of calcite by the bulk of the material. This technology applies to CO2 fixation and self-healing cement using reactive polymer vesicles.

scholarly journals Synergistic Assessment of Sustained Casing Pressure on Oil Well

2013 ◽  
Vol 5 (17) ◽  
pp. 4246-4256
Author(s):  
Darren Wong Vun Nyap ◽  
Mohd Amin Shoushtari ◽  
Ruslan Masharipov Rashidovich
Keyword(s):  
Oil Well ◽  
Sustained Casing Pressure ◽  
Casing Pressure
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