Mitigation of Annulus Pressure Buildup in Offshore Gas Wells by Determination of Top of Cement

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Alex W. Mwang’ande ◽  
Hualin Liao ◽  
Long Zeng
Keyword(s):  
Field Data ◽  
Gas Wells ◽  
Gas Well ◽  
Pressure Buildup ◽  
Cheap Method ◽  
Calculation Results ◽  
Sustained Casing Pressure ◽  
Casing Pressure ◽  
Mitigation Methods

Annulus pressure buildup (APB) is still a serious problem in offshore gas wells, which threatens the safety of wells for the entire phases of drilling, completion, and production. The existing methods for mitigating APB are technically complex and highly costly. Setting top of cement (TOC) below the outer casing shoe to mitigate APB is easy to implement and can significantly reduce costs. However, there are no unified methods of determining TOC for this purpose. Nevertheless, existing petroleum standards give ambiguous regulations on the setting of TOC. This article brings a new and cheap method of mitigating APB by determining best TOC settings using a mathematical model for calculating APB from both annulus fluid expansion (AFE) and sustained casing pressure (SCP). Field data from gas well X are inputted to the model to describe how it serves this purpose. Calculation results for well X show that setting TOC's above and below the upper casing shoes for production and intermediate casings annuli, respectively, can greatly avoid the problem of APB and the costs associated with the existing mitigation methods. This technique can be used to other wells following the same procedures. The developed model reduced greatly the ambiguity of TOC determination as it helps to get the clear TOC combinations that control APB at the lowest cost of well construction while maintaining good and safe well operation.

Avoiding Sustained Casing Pressure in Gas wells using Self Healing Cement

2011 ◽  
Author(s):  
Salim Taoutaou ◽  
Jorge Andres Vargas Bermea ◽  
Pietro Bonomi ◽  
Bassam Elatrache ◽  
Christian Pasturel ◽  
...  
Keyword(s):  
Self Healing ◽  
Gas Wells ◽  
Sustained Casing Pressure ◽  
Casing Pressure

Sustained Casing Pressure Calculation of A Annulus Induced by Downhole Operation Load

2012 ◽  
Vol 430-432 ◽  
pp. 2067-2070
Author(s):  
Zhang Zhi ◽  
Tai Ping Xiao ◽  
Zheng Mao Chen ◽  
Tai He Shi
Keyword(s):  
Internal Pressure ◽  
Safety Evaluation ◽  
Calculation Model ◽  
Extrusion Force ◽  
External Diameter ◽  
Gas Well ◽  
Seal Failure ◽  
Theoretical Support ◽  
Sustained Casing Pressure ◽  
Casing Pressure

Currently the annulus pressure of gas well becomes more common, so the safe production of several wells has been seriously affected. The annulus pressure mechanism is relatively complex, and it can be approximately classified into annulus pressure induced by temperature effect, by ballooning effect and by leakage or seal failure etc. The article mainly focuses on the annulus pressure mechanism induced by ballooning effect and the corresponding calculation model. For the tubing column with two ends fixed and closed, when tubing internal pressure is larger than the external extrusion force, the external diameter of the tubing column balloons (i.e. ballooning effect). It reduces the annular volume between the tubing and the casing, and consequentially induces annulus pressure. Based on the fundamental theory of elastic-plastic mechanics, the tubing column is simplified into the thin walled cylinder so as to deduce the relation models between the internal pressure and its swell capacity and A annulus pressure value, which provide theoretical support for safety evaluation on annulus pressure and the next treatment program.

Research on Residual Strength of Corroded Tubing of Gas Well With Sustained Casing Pressure

2015 ◽  
Author(s):  
Li Sun ◽  
Jianchun Fan ◽  
Xing Meng ◽  
Ximing Zhang ◽  
Yuting Sun ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Residual Strength ◽  
Equivalent Stress ◽  
External Pressure ◽  
Defect Depth ◽  
Gas Well ◽  
Sustained Casing Pressure ◽  
Von Mises Equivalent Stress ◽  
Von Mises ◽  
Casing Pressure

Corrosion and sustained casing pressure have serious threats to the integrity of tubing of gas well. Researching the residual strength of corroded tubing has great significance to ensure the safety of gas well. The finite element method was used to study the relationships between residual strength and corrosion defects size, internal pressure, external pressure, axial load. The results show that, for tubing with uniform corrosion, the defect depth, internal pressure and external pressure have greater impacts on the von Mises equivalent stress of tubing, and the defect width and defect length have little effects on it. For tubing with pitting corrosion, the defect depth, internal pressure and external pressure have greater impacts on the von Mises equivalent stress of tubing, while the defect radius has little effect on it. These simulation data were fitted into the functions of residual strength of corroded tubing according to different corrosion morphology types. Both of the verifications of the fitting results show that most of the error between the original calculation data and the fitting calculation data is less than 4%. The fitting formulas can be used conveniently to evaluate the safety of the tubing of gas well with sustained casing pressure.

Determination of Average Reservoir Pressure from Pressure Buildup Tests

1972 ◽  
Author(s):  
Hossein Kazemi
Keyword(s):  
Reservoir Pressure ◽  
Well Test ◽  
Well Test Analysis ◽  
Test Analysis ◽  
Gas Well ◽  
Pressure Buildup ◽  
Production History ◽  
Calculated Average

Abstract Two simple and equivalent procedures are suggested for improving the calculated average reservoir pressure from pressure buildup tests of liquid or gas wells in developed reservoirs. These procedures are particularly useful in gas well test analysis irrespective of gas composition, in reservoirs with pressure-dependent permeability and porosity, and in oil reservoirs where substantial gas saturation has been developed. Long-term production history need not be known. Introduction For analyzing pressure buildup data with constant flowrate before shut in, two plotting procedures are mostly used: The Miller-Dyes-Hutchinson (MDH) plot (1,8) and the Horner plot (2,8). The Miller-Dyes-Hutchinson plot is a plot of pws vs log Δt. The Horner plot consists of plotting the bottom hole shut-in pressure, pws vs log [(tp + Δt)/Δt]. Δt is the shut-in time and tp is a pseudo-production time equal to the ratio of total produced fluid and the last stabilized flowrate prior to shut in. This method was first used by Theis (3) in the water industry.

Plug and Abandonment for Gas Wells: A Case Study from Baghjan Oilfield, India

2021 ◽  
Author(s):  
Rishabh Bharadwaj ◽  
Bhavya Kumari ◽  
Astha Patel
Keyword(s):  
Capital Investment ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Sodium Formate ◽  
Environmental Damage ◽  
Fluid Loss ◽  
Cement Slurry ◽  
Gas Wells ◽  
Gas Well ◽  
Casing Pressure

Abstract The economic end of the life-cycle of a well is dynamic and it varies with the oil & gas market conditions and advances in extraction technologies. If production declines or the need for a workover arises, plugging and abandonment operations are followed. In case the wellsite has encountered accidental releases, systematic abandonment and remediation becomes even more crucial to avoid further environmental damage and capital investment. This paper analyzes the Baghjan oilfield blowout of the Assam-Arakan basin and provides abandonment practices for gas wells. The mobile workover rig was stationed at the Baghjan Well-5 with the aim to plug the lower producing zone at 3871 m and complete the well in the upper Lakadong+Therria sand at a depth of 3739 m. Baghjan Gas Well No.5 blew during the temporary abandonment which was planned to mitigate the leakage in the wellhead. Improper depth for the placement of cement plug, failure to check the plug integrity, and shortcomings in the regular inspection of annular casing pressure led to the well control situation at the Baghjan gas well. While pulling out the tubing conveyed perforation gun after perforating the Lakadong+Therria I+II sand, Shut-In Tubing Pressure of 4400 psi and 3900 psi Shut-In Casing Pressure was observed which indicated a leak in the Tubing Seal Assembly. The well was killed with a 9.76 lbm/gal sodium formate brine and in the middle of pulling the tubing, leakage in the W.F. Spool was identified which changed the priority of the operations. Therefore, a temporary abandonment operation was planned to mitigate the leakage problem in the primary and secondary seals, during which the well started flowing gas profusely after nipple-down of the blowout preventer. The shortcomings of the abandonment process can be conquered by the selection of an appropriate isolation material such as resin-based sealants or bismuth and thermite, which shall act as a primary barrier and provide enhanced zonal isolation. The isolation material should mitigate micro-fractures, minimize treatment volume and fluid loss, provide ample pumping time, and not degrade in the presence of wellbore fluids. The study discusses resin-based sealants, cement slurry designs, advances in conventional, unconventional, and rigless abandonment techniques, and suggests the most efficient method for the temporary and permanent abandonment operations to avoid further such incidents in the oil and gas industry.

Lessons Learned and Case Studies of Overcoming Sustained Casing Pressure in Extended-Reach Wells

2021 ◽  
Author(s):  
Svetlana Nafikova ◽  
Yulia Ramazanova ◽  
Alexander Muslimov ◽  
Ilshat Akhmetzianov ◽  
Bipin Jain ◽  
...  
Keyword(s):  
Best Practices ◽  
Caspian Sea ◽  
The Self ◽  
Self Healing ◽  
Effective Solution ◽  
Pressure Buildup ◽  
Cement System ◽  
Sustained Casing Pressure ◽  
Zonal Isolation ◽  
Casing Pressure

Abstract Achieving zonal isolation for the lifetime of oil and gas wells is crucial for well integrity. Poor zonal isolation can detrimentally affect well economics and increase safety-related risks because of pressure buildup with unpredictable consequences. Additional local regulations prohibiting production of a well with positive pressure in the annulus made sustained casing pressure a major challenge for operators in the North Caspian Sea. An innovative cost-effective solution was required to resolve this challenge. Historical well analysis proved that previously applied cementing approaches were ineffective. Several modifications were required to define the effective solution. Implemented changes included revision of the casing setting depth, optimization of the drilling fluids and spacer formulations, and implementation of the self-healing expanding cement. Carefully engineered placement of the self-healing cement system was the key to success. If cracks or microannuli occur and hydrocarbons reach the cement and flow through the cracks, the system has the capability to repair itself, thus restoring integrity of the cement sheath without external intervention. This technology has been used in 11 extended reach wells in two fields with excellent results. The collaborative approach with drilling engineers eliminated the challenging sustained casing pressure issue in two major offshore fields in North Caspian Sea. In addition to the existing cementing best practices available in industry for mud removal efficiency enhancement and successful cement placement, the newly implemented methodology included potential requirements for well trajectory adjustments, implementation of the real-time control during cementing job execution, engineered placement and optimization of the self-healing expanding cement system formulation, and a specifically developed "initially required" bleedoff schedule that allows acceleration of the self-remediation cement capability. The self-healing cement was designed with low Young's modulus for maximum flexibility. Expanding additives were also incorporated into the design to minimize the risk of set cement integrity failure due to microdebonding from bulk shrinkage after setting. Adherence to the mutually developed flowchart for the drilling and cementing stages improved the zonal isolation of the critical hydrocarbon zones in the extended reach wells and increased the success ratio of the wells with no pressure buildup from 30% to almost 100% within the last 5 years. As a result, the self-healing cement technology and developed approach, which is discussed in this paper, have become the standard for both fields for all future wells. The complex engineering approach described in this paper expands the existing best practices in the industry for zonal isolation improvement of the extended reach wells and provides a new effective solution for eliminating sustained casing pressure problems. The design strategy, execution, evaluation, and results for two sample wells are discussed in detail to help to guide future engineering and operational activities around the world.

Avoiding Sustained Casing Pressure in Gas wells using Self Healing Cement

2011 ◽  
Author(s):  
Salim Taoutaou ◽  
Jorge Andres Vargas Bermea ◽  
Pietro Bonomi ◽  
Bassam Elatrache ◽  
Christian Pasturel ◽  
...  
Keyword(s):  
Self Healing ◽  
Gas Wells ◽  
Sustained Casing Pressure ◽  
Casing Pressure
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