Surface Casing Pressure As an Indicator of Well Integrity Loss and Stray Gas Migration in the Wattenberg Field, Colorado

2017 ◽  
Vol 51 (6) ◽  
pp. 3567-3574 ◽  
Author(s):  
Greg Lackey ◽  
Harihar Rajaram ◽  
Owen A. Sherwood ◽  
Troy L. Burke ◽  
Joseph N. Ryan
Keyword(s):  
Gas Migration ◽  
Wattenberg Field ◽  
Well Integrity ◽  
Casing Pressure

Well Integrity Enabled by Digital Workflow

2021 ◽  
Author(s):  
B. Brechan (Wellviz) ◽  
A. Teigland ◽  
S. Dale ◽  
S. Sangesland
Keyword(s):  
Fiber Optics ◽  
Risk Level ◽  
Gas Migration ◽  
Digital Workflow ◽  
Well Integrity ◽  
Digital Format ◽  
Standard Procedures ◽  
Safety Margins ◽  
Sustained Casing Pressure ◽  
Casing Pressure

Abstract Emerging technologies are expected to provide step changes in many areas within planning, making and production of wells. The main topic of this paper covers in a digital workflow, where the different disciplines contributions to well integrity are expected to be on a fully digital format. All phases in the lifecycle of wells are integrated into one digital process, where possible improvements are enabled by the transition from a human oriented work process to a software oriented (human supported) process. This transition has taken place in several other comparable energy and capital-intensive industries. Today, some wells have the new fiber optics that enables a range of opportunities for improvement of well integrity. Distributed Acoustic Sensing (DAS) has measurements for every meter, which provides new aspects such as in situ measurements during cement jobs and drilling. Other applications of the new fiber optic technology are monitoring of gas migration, source of sustained casing pressure and other measurements which have the potential to develop into standard procedures or even regulatory requirements. With gas migration, corrosion and other changes affecting the integrity of the well construction, integrity can be re-modelled and updated automatically in a fully digital workflow to understand the safety margins. A part of this digital process is automating the risk level for each well and the entire asset. These processes and the prototype of the automated risk assessment are possible in a fully digital process, where planning and well construction commence with support from modern well planning and integrity software.

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%.

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.

WELL INTEGRITY IN COLORADO'S DENVER-JULESBURG BASIN: CONVENTIONAL VS. UNCONVENTIONAL WELLS AND IMPLICATIONS FOR STRAY GAS MIGRATION

2016 ◽  
Author(s):  
Greg Lackey ◽  
◽  
Harihar Rajaram ◽  
Owen A. Sherwood ◽  
Troy L. Burke ◽  
...  
Keyword(s):  
Gas Migration ◽  
Well Integrity

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.

Pilot-Scale Experimental Study and Mathematical Modeling of Buoyant Settling of Immiscible Heavy Fluid in Mud To Stop Annular-Gas Migration Above Leaking Cement

SPE Journal ◽  
2017 ◽  
Vol 23 (01) ◽  
pp. 186-204
Author(s):  
Efecan Demirci ◽  
Andrew K. Wojtanowicz
Keyword(s):  
Pressure Change ◽  
Pilot Scale ◽  
Injection Rate ◽  
Gas Migration ◽  
Heavy Fluid ◽  
Process Measures ◽  
Gas Leakage ◽  
Two Fluids ◽  
High Dependency ◽  
Casing Pressure

Summary Annular casing pressure (ACP) is defined as the accumulated pressure on the casing head. If pressure returns after bleed-down, then the casing annulus is said to be showing sustained casing pressure (SCP). SCP is caused by late gas migration in the annular-fluid column above the top of leaking cement and may result in atmospheric emissions or underground blowouts. Removal of SCP is required in places where SCP is regulated, particularly before the well-plugging and abandonment operations. Annular-intervention methods for SCP removal, which are less expensive than the conventional downhole-intervention methods, typically involve injecting heavy fluid into the affected annulus that would displace the annular fluid (AF), balance the pressure at the top of cement, and stop the gas leakage. Previous studies stated that the use of immiscible combinations of two fluids is more effective for the purpose; however, inattentive applications may result in excessive use of heavy fluid. In this study, a 20-ft carbon-steel pilot-well annulus was manufactured and used for displacement experiments with various water-based drilling muds and heavy fluids with different properties. Pressure-change data were collected from four different levels of the annulus, and volumes of fluids going in and out of the annulus were measured. Experiments indicated the formation of a mixture zone that would build bottoms up and expand during ongoing displacement. The proposed pressure-buildup model suggests an exponential distribution of density of this zone, and shows its high dependency on fluids’ properties and injection rate. The mathematical models were also converted into dimensionless process measures and proposed for use in real-well applications. The study demonstrates the viability and recommends the correct application of the method.

Foamed Cement Analysis With Computed Tomography

2014 ◽  
Author(s):  
Dustin Crandall ◽  
Magdalena Gill ◽  
Johnathan Moore ◽  
Barbara Kutchko
Keyword(s):  
Computed Tomography ◽  
High Stress ◽  
Three Dimensional ◽  
Image Data ◽  
Gas Migration ◽  
Structure Quality ◽  
Air Voids ◽  
Well Integrity ◽  
X Ray Computed

Foamed cements are widely used for cementing oil or gas wells that require lightweight slurries, gas migration prevention, or wells in high-stress environments. When this manufactured slurry solidifies in the sub-surface environment the distribution of gas voids can affect the resultant strength, permeability, and stability of the wellbore casing. Researchers at the National Energy Technology Laboratory have produced the first high-resolution X-ray computed tomography (CT) three-dimensional images of atmospheric and field generated foamed cement across a range of foam qualities. CT imaging enabled the assessment and quantification of the foamed cement structure, quality, and bubble size distribution in order to provide a better understanding of this cement. Ultimately, this research will provide industry the knowledge to ensure long-term well integrity and safe operation of wells in which foamed cements are used. Initial results show that a systematic technique for isolating air voids can give consistent results from the image data, laboratory generated foamed cements tend to be uniform, and that high-gas fraction foamed cements have large interconnected void spaces.

scholarly journals Analytical and Experimental Investigation of the Critical Length in Casing–Liner Overlap

2019 ◽  
Vol 11 (23) ◽  
pp. 6861 ◽  
Author(s):  
Mustafa Al Ramadan ◽  
Saeed Salehi ◽  
Chinedum Ezeakacha ◽  
Catalin Teodoriu
Keyword(s):  
Critical Length ◽  
Fluid Migration ◽  
Test Duration ◽  
Gas Migration ◽  
Gas Leakage ◽  
Pressure Test ◽  
Seal Assembly ◽  
Casing Pressure ◽  
The Cost ◽  
Selection Of

Offshore drilling operations exhibit various difficulties attributed to shallow flows worldwide. One of the most common practices for drilling offshore wells is to use liners and liner hangers rather than using full casing strings. This reduces the cost of drilling operation. Liners and liner hangers are required to pass certain standards prior to their deployment in the field. This ensures their ability to withstand harsh downhole conditions and maintain the integrity of the well. A liner hanger contains an integrated seal assembly that acts as a barrier to prevent fluid migration. The cement that is placed within the casing–liner overlap is also considered a barrier, and it is critical that it maintains the integrity of the well by mitigating fluid migration to other formations and to the surface. The failure of this dual barrier (cement and seal assembly) system to seal the annular space can result in serious problems that might jeopardize a well’s integrity. Typically, in field applications, the length of a casing–liner overlap is chosen arbitrarily. In some cases, shorter overlaps (50 to 200 ft) are chosen because of the lower cost and easy identification of leaks during pressure tests. However, some loss of well control incidents (particularly the incident that motivated this study) have been linked to fluid leakages along the casing–liner overlap. This paper investigates the critical length of the casing–liner overlap by modeling gas leakage through the cement placed within the overlap using analytical and experimental approaches. Leakage scenarios were developed to mimic gas migration within the cement in the casing–liner overlap. The results showed that the longer the casing–liner overlap, the higher the leakage time. The results also showed that the current casing pressure test duration of 30 min may not be adequate to verify the integrity of the cement within the overlap. Based on the results and analyses, it is recommended to increase the pressure test duration to 90 min. In addition, the results suggest that the length of the casing–liner overlap should not be less than 300 ft to maintain the integrity of the well in the case of gas influx. Further details are highlighted in the results section. In practice, the current rationale behind the selection of a casing–liner overlap length is not sustainable. Thus, the major advantage of this study is that with field data, it provides both scientific and research-based evidence that can be used to inform the decision behind the selection of the casing–liner overlap length, especially in gas migration-prone zones.

scholarly journals Securing Annulus Abnormal Pressure Build-up (APB) with Polymer Plug; a Case Study

2020 ◽  
Vol 1 (2) ◽  
pp. 62
Author(s):  
Ganesha R Darmawan
Keyword(s):  
Operating Pressure ◽  
Gas Migration ◽  
Well Control ◽  
Well Integrity ◽  
Abnormal Pressure ◽  
Additional Challenge ◽  
Cement Plug ◽  
Planning And Operation ◽  
Integrity Issue

The life cycle of a production well was facing challenges related to well integrity issue where A-Annulus pressure tracking the tubing pressure and increased repeatedly above the Maximum Allowable Wellhead Operating Pressure (MAWOP). Several well control operations were executed to reduce A-Annulus abnormal pressure build-up (APB) with no success.Literature and well historical studies were performed in order to secure this well, normal bleed and lube was ruled out owing to several attempts already performed for more than a year, but the APB keep on appearing after 2-4 months. Bullheading is not a viable option to kill the well. Well securing planned and prepared with some options such as, mechanical barriers/plugs, cement plug or polymer plugs as temporary plug to avoid APB re-occurrence. There were some constrains in operation planning that need to be addressed carefully, with additional challenge of tight injectivity as if it was a closed system.The polymer plug successfully stops the gas migration to surface, and secured the well from any reoccurrences of APB. The details of well control histories, operation design and planning and operation execution with the complete results and evaluation will be presented in this paper.

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