A review of the evaluation methods and control technologies for trapped annular pressure in deepwater oil and gas wells

This study is focused on the design of the subsea accumulators currently used to deliver a pressurized fluid whose function is to actuate safety operations on a subsea well. API 16D, whose specifications regulate the design method of a bank of accumulators, was revised, discussed, and resumed in terms of a nomogram whose engineering value is useful for designers. An additional nomogram was derived allowing to perform the verification process which is suggested by the norm, in order to verify the fulfillment of the actuations requested to the accumulators. This verification phase caught the interest of the Authors: API 16D assumes for the design that the Functional Volume Requirement (FVR)the sum of the quantities of pressurized fluid to be delivered for different sequenced-in-time functions -is delivered at the Minimum Operating Pressure (MOP) requested by the last actuation. This hypothesis simplifies the design, but the result cannot fulfill the previous functions because of the pressure lack (energy content in the pressurized propelling gas) which can happen. The use of the two nomograms proposed simplifies the application of the design procedure and allow to discuss main sensitivities of the variables involved (FVRs & MOPs), evidencing which variables deserve more attention and accuracy. In particular, the use of the second nomogram permits to verify that the right volumes of fluid during the actuations are delivered above a minimum pressure level, so guaranteeing the fulfillment of the function. It is based on a thermofluid-dynamic discharge modeling of the accumulators. The paper outlines a design direction which minimizes the number of accumulators and opens the way to a different design approach, based on a fully physical discharge process description. 240

Section: Modeling and Analysismentioning

confidence: 87%

On the rapid discharge of subsea accumulators: remarks on the normed design method and proposal of improvement

Cipollone

Fatigati

Battista

et al. 2018

“…The deficiency of nitrogen shrinking spacer is complex technology and expensive devices. 3 As analyzed above, most of the mitigations are reliable and easy to achieve the APB mitigation, while the disadvantage of these methods is quite expensive. 1 Insulating tubing and casing and insulating packer fluid are another two reliable methods to avoid APB induced by annular temperature mitigation.…”

Section: Comparison Of Pressure Relief Effect With Other Mitigationmentioning

confidence: 99%

“…16,29 However, the cost of these mitigation methods is high. 3 As analyzed above, most of the mitigations are reliable and easy to achieve the APB mitigation, while the disadvantage of these methods is quite expensive. The pressure relief method is economic but lack of reliability.…”

Section: Comparison Of Pressure Relief Effect With Other Mitigationmentioning

confidence: 99%

“…However, high temperature and high pressure (HTHP) is a common problem in exploration of offshore oil and gas resources. 3 The casing may be burst or collapsed when the APB is high enough, and it is a very complicated and expensive downhole problem for deepwater wells. 2 In the production process, high-temperature tubing fluids heating the sealed annulus result in annular fluids thermal expansion; this phenomenon is so-called annular pressure buildup (APB).…”

Section: Introductionmentioning

confidence: 99%

“…2 In the production process, high-temperature tubing fluids heating the sealed annulus result in annular fluids thermal expansion; this phenomenon is so-called annular pressure buildup (APB). 3 The casing may be burst or collapsed when the APB is high enough, and it is a very complicated and expensive downhole problem for deepwater wells. 4 Consequently, developing a reliable and economic mitigation method is important to exploit deepwater HTHP oil and gas resources safely and efficiently.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mitigation of annular pressure buildup for deepwater wells using a recovery relief method

Tang

Chen

et al. 2019

Self Cite

Annular pressure buildup (APB) is induced by high‐temperature tubing fluid heating the trapped annular fluid, which leads to liquid thermal expansion at the production stage in deepwater wells. Casing would be burst or collapsed without APB mitigation. A novel recovery relief method was adopted to mitigate APB through the principle of differential pressure. To assess the application effect of the method, APB prediction model and pressure relief threshold determination method were proposed, where the transient heat transfer and volume and pressure coupling were involved. The laboratory test of the principle prototype was conducted so that the feasibility of the recovery relief method was validated. The numerical APB mitigation effect was simulated by the field example. The production simulation results indicated that the high‐temperature‐induced APB caused casing failure. The simulation of APB mitigation with both inward and outward directions demonstrated that the casings using outward mitigation method were safer with lower safe factor. Besides, comparing the mitigating effect to the rupture disk, the recovery relief method had more maximum allowable APB of annulus A. Additionally, compared to other 11 ordinary mitigation methods with the qualities of engineering reliability, technology feasibility, and economy, the recovery relief method had best mitigation performance. Therefore, the recovery relief method was recommended for APB mitigating practice.

Study on annular pressure buildup phenomenon in subsea wells considering the effect of cement

Wang

Zhang

Jun

et al. 2021

Marine petroleum is important fossil energy that accounts for about 34% of the total global petroleum resource. With the improvement of the exploitation technology, the production of the marine fossil resource become one of the main sources of world oil and gas production growth. Studying the engineering problems in the production of marine petroleum is of great economic significance. In the development of marine oil and gas, annular pressure buildup (APB) is an important problem that has received extensive attention. 1 In the production of the offshore oil field, the wellbore structure is constructed with casings and cement. Annuli between the casings are isolated and sealed in most wells, as is shown in Figure 1. The fluid remaining in annuli is heated when the oil and steam