Oil and Gas Wells: Enhanced Wellbore Casing Integrity Management through Corrosion Rate Prediction Using an Augmented Intelligent Approach

Wellbore integrity management for oil and gas wells plays a vital role throughout the typical lifespan of a well. Downhole casing leaks in oil- and gas-producing wells significantly affect their shallow water horizon, the environment, and fresh water resources. Additionally, downhole casing leaks may cause seepage of toxic gases to fresh water zones and the surface, through the casing annuli. Forecasting of such leaks and proactive measures of prevention will help eliminate their consequences and, in turn, better protect the environment. The objective of this study is to formulate an effective, robust, and accurate model for predicting the corrosion rate of metal casing string using artificial intelligence (AI) techniques. The input parameters used to train AI models include casing leaks, the percentage of metal loss, casing age, and average remaining barrier ratio (ARBR). The target parameter is the corrosion rate of the metal casing string. The dataset from which the AI models were trained was comprised of 250 data points collected from 218 wells in a giant carbonate reservoir that covered a wide range of practically reasonable values. Two AI tools were used: artificial neural networks (ANNs) and adaptive network-based fuzzy inference systems (ANFISs). A prediction comparison was made between these two tools. Based on the minimum average absolute percentage error (AAPE) and the highest coefficient of determination (R2) between the measured and predicted corrosion rate values, the ANN model proposed here was determined to be best for predicting the corrosion rate. An ANN-based empirical model is also presented in this study. The proposed model is based on the associated weights and biases. After evaluating the new ANN equation using an unseen validation dataset, it was concluded that the ANN equation was able to make predictions with a significantly lower AAPE and higher R2. Use of the proposed new equation is very cost-effective in terms of reducing the number of sequential surveys and experiments conducted. The proposed equation can be utilized without an AI engine. The developed model and empirical correlation are very promising and can serve as a handy tool for corrosion engineers seeking to determine the corrosion rate without training an AI model.

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Risk-Based Approach to Evaluate Casing Integrity in Upstream Wells

Journal of Energy Resources Technology ◽

10.1115/1.4040237 ◽

2018 ◽

Vol 140 (12) ◽

Cited By ~ 1

Author(s):

Mohammed D. Al-Ajmi ◽

Dhafer Al-Shehri ◽

Mohamed Mahmoud ◽

Nasser M. Al-Hajri

Keyword(s):

Fresh Water ◽

Oil And Gas ◽

Probabilistic Approach ◽

Metal Loss ◽

Gas Wells ◽

Wrong Decision ◽

Average Value ◽

Oil And Gas Wells ◽

Proactive Measures ◽

Casing Failure

Downhole casing leaks in oil and gas wells will highly impact the shallow water horizons and this will affect the environment and fresh water resources. Proactive measures and forecasting of this leak will help eliminate the consequences of downhole casing leaks and, in turn, will protect the environment. Additionally, downhole casing leaks may also cause seepage of toxic gases to the fresh water zones and to the surface through the casing annuli. In this paper, we introduced a risk-based methodology to predict the downhole casing leaks in oil and gas wells using advanced casing corrosion logs such as electromagnetic logs. Downhole casing corrosion was observed to assess the remaining well life. Electromagnetic (EM) corrosion logs are the current practice for monitoring the casing corrosion. The corrosion assessment from EM logs is insufficient because these logs cannot read in multiple casings in the well. EM tool gives average reading for the corrosion in the casing at a specific depth and it does not indicate the orientation of the corrosion. EM log does not assess the 360 deg corrosion profile in the casing and it only provides average value and this may lead to wrong decision. All of this makes EM logs uncertain tools to assess the corrosion in the downhole casing. A unified criterion to assess the corrosion in the casing and to decide workover operations or not has been identified to minimize the field challenges related to this issue. A new approach was introduced in this paper to enhance the EM logs to detect the downhole casing corrosion. Corrosion data were collected from different fields (around 500 data points) to build a probabilistic approach to assess the casing failure based on the average metal loss from the EM corrosion log. The failure model was used to set the ranges for the casing failure and the probability of casing failure for different casings. The prediction of probability of failure (PF) will act as proactive maintenance which will help prevent further or future casing leaks.

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Development and Improvement of Organic Salt Solutions of Potassium Citrate As An Environmentally Friendly Completion Fluids for Oil and Gas Wells

10.29118/ipa21-e-279 ◽

2021 ◽

Keyword(s):

Corrosion Rate ◽

Oil And Gas ◽

Fluid Pressure ◽

Environmentally Friendly ◽

Potassium Citrate ◽

Organic Salt ◽

Salt Solutions ◽

Gas Wells ◽

Oil And Gas Wells ◽

Swelling Rate

This article provides information on the utilization and development of colloidal formulations based on organic potassium citrate, an alternative, environmentally friendly composite fluid that can support the drilling and production of oil and gas wells. The activity started with a laboratory-scale literature study, the formulation and modification of organic potassium citrate, testing the characteristics and performance of liquids, and improving advanced formulations. This completion fluid based on organic potassium citrate has high solubility and good stability to other pollutant particles. The colloidal organic salt system based on potassium citrate is an alternative function of the replenishment fluid (pressure holding fluid) for cleaning/deepening oil and gas wells. Currently, widely used composite fluids are chloride (Cl-), bromide (Br-), nitrate (NO3-), phosphate (PO4-), and cesium formate. However, these salt solutions are highly corrosive and are not environmentally friendly. The swelling test and the corrosion rate test are carried out using different fluids (i.e., KCl slurry, NaCl polymer, and colloidal organic citrate). The test results show that when the test is performed at room temperature for 16 hours, the organic citrate fluid's swelling rate is lower than 10%, and the KCl and NaCl sludge is higher than 20%. The result of a seven days corrosion test at 350oF is that the citric acid organic liquid is lower than 10 mpy, while KCl and NaCl are higher than 50 mpy. This completion fluid formulation based on organic citrate salts is a new type of completion fluid that has the following specifications: density up to (1.80), corrosion rate (3.19 mpy) @ 248-350oF, pH (6-8), resistance to extreme temperature, turbidity (7 NTU), a swelling rate below 10%, and has good compatibility with formation water. Also, potassium citrate organic salts can be degraded efficiently, making them safe for the environment.

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Designing, Making, and Testing Syntactic Foam of Precisely Controlled Hydrostatic Strength

Volume 3: Materials Technology; Ocean Engineering; Polar and Arctic Sciences and Technology; Workshops ◽

10.1115/omae2003-37199 ◽

2003 ◽

Cited By ~ 5

Author(s):

Wen-Tsuen Wang ◽

Lou Watkins

Keyword(s):

Oil And Gas ◽

Syntactic Foam ◽

Confined Space ◽

Foam Material ◽

Gas Wells ◽

Wide Range ◽

Oil And Gas Wells ◽

Temperature And Pressure ◽

Offshore Oil And Gas ◽

Offshore Oil

This paper describes a recently developed syntactic foam material designed to collapse under precisely defined conditions of temperature and pressure to protect ultra-deep high pressure offshore oil and gas wells. Each grade of syntactic foam is engineered to have a specific set of characteristics, tailored for the region of the well it occupies. In the startup phase, the materials remain intact, with no significant volume change. As pressure and temperature in the well rise during operations, the materials begin to compress and relieve pressure in the narrow, confined space of the annulus. Finally, when conditions reach preset limits, the syntactic foam undergoes a sudden and dramatic collapse, preventing excessive overpressure, and protecting the steel casing. An important advantage of this material is that it is passive, requiring no controls or active intervention. It responds automatically to protect the well casing from overpressures and temperature spikes. The properties of the material can be adjusted to suit a wide range of conditions inside a given well, or from one well to another.

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Geothermal Repurposing of Depleted Oil and Gas Wells in Italy

Proceedings ◽

10.3390/wef-06907 ◽

2020 ◽

Vol 58 (1) ◽

pp. 9

Author(s):

Elena Soldo ◽

Claudio Alimonti ◽

Davide Scrocca

Keyword(s):

Energy Demand ◽

Oil And Gas ◽

Preliminary Investigation ◽

Mature Stage ◽

Global Changes ◽

Gas Wells ◽

Oil And Gas Fields ◽

Wide Range ◽

Oil And Gas Wells ◽

Gas Fields

The decarbonisation of the energy sector is probably one of the main worldwide challenges of the future. Global changes urge a radical transformation and improvement of the energy-producing systems to meet the decarbonisation targets and a reduction of greenhouse gas emissions. The hydrocarbon industry also contributes to this transition path. In a mature stage of oil and gas fields, the production of hydrocarbons is associated with formation waters. The volume of produced water increases with the maturity of the assets and the geothermal repurposing of depleted oil and gas wells could be an alternative to the mining closure. In the described transition scenario, the geothermal energy seems very promising because of its wide range of applications depending on the temperature of extracted fluids. This flexibility enables us to propose projects inspired by a circular economic vision considering the integration in the territory and social acceptance issues. In Italy, since 1985, 7246 wells have been drilled for hydrocarbon, of which 898 are located onshore with a productive or potentially productive operational status. This paper presents a preliminary investigation of oil and gas fields located onshore in Italian territory based on the available information on temperature distribution at different depths. Then, taking into account the local energy demand, existing infrastructure, and land use of the territory, a conversion strategy for the producing wells is proposed for three case studies.

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Evaluation of High Dissolving-Power Retarded Acid Recipes for Carbonate Acidizing

10.2118/205542-ms ◽

2021 ◽

Author(s):

Norah Aljuryyed ◽

Abdullah Al Moajil ◽

Saeed Alghamdi ◽

Sajjad AlDarweesh

Keyword(s):

Hydrochloric Acid ◽

Corrosion Rate ◽

Carbonate Rock ◽

Reaction Rate ◽

Oil And Gas ◽

Gas Wells ◽

Low Viscosity ◽

Oil And Gas Wells ◽

Carbonate Acidizing ◽

Acid Retardation

Abstract Development of retarded acid recipes that can have both adequate dissolving power and controllable reaction rate is desired to maximize the effectiveness of matrix stimulation treatments for oil and gas wells. Hydrochloric acid (HCl) has high dissolving power, however, the reaction rate with carbonate rock is uncontrollable and can cause face dissolution. Organic acids have low dissolving power and controllable reaction rate. The objective of this paper was to compare the effectiveness of three low viscosity retarded acid recipes with dissolving powers of 15 wt% and >20 wt% HCl equivalent. The examined acid recipes were 15/28 wt% emulsified acids, retarded acid recipes #1, #2 and #3, and 15/26 wt% HCl. The emulsified acids were at 30:70 ratio of diesel to acid. The retarded acid recipes were prepared at different dissolving power. Retarded acid recipe #3 was equivalent to 15 wt% HCl while retarded acid recipes #1 and #2 were equivalent to >20 wt% HCl. The calcite disc dissolution rate with retarded acids #1 and #2 was significantly lower than 26 wt% HCl and comparable to 15 wt% HCl at 75°F. The solubility of calcite discs in the retarded acid recipe #3 showed acid retardation higher than retarded acid recipes #1 and #2. The corrosion rate of retarded acid recipes #1 and #2 were 0.003-0.015 lb/ft2 at 250°F and 6 hrs, lower than both examined 26-28 wt% HCl and emulsified acids. The pitting indices of retarded acid recipes #1, #2, and #3 were 4, 2, and 1 respectively at 300°F. The pore volumes to breakthrough (PVBT) of retarded acid recipes #1 and #2 were slightly higher than retarded acid recipes #3 at 200°F. The PVBT values for 15 wt% and 28 wt% emulsified acid was comparable to retarded acid recipes #1, #2, and #3, confirming their retardation was effective.

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