Generating Value from Mature Gas Fields by Quantifying Well Integrity Assurance with a Critical Analysis of Multiple Logs & Retrieved Tubular Surface Inspection

Sharjah National Oil Corporation (SNOC) operates 4 onshore gas condensate reservoirs of which 3 are very mature consisting of 50+ wells producing corrosive hydrocarbons for over 30 years. The integrity of these legacy wells is frequently questioned before any development is conceptualized, thus making it critical to evaluate the well integrity. The cost associated with pulling completions for their evaluation and running logs in all wells is significant and the availability of various emerging technologies for corrosion analysis in the market makes it challenging to choose the most reliable one. This paper focuses on the detailed analysis and comparison of electromagnetic thickness logs run in 10% of the well stock from 2016 to post-workover surface inspection of the downhole recovered tubing's in 2020/21. It also quantifies how correlating different logging technologies for well integrity increases the reliability of the electromagnetic technology applied on offset wells. The paper also showcases a comparison between mechanical and electromagnetic thickness evaluation of the production casing in-situ. Data from all the available logs from past 5 years was compiled for 6 wells. On recovery of the downhole completion tubings via a hydraulic workover, an ultrasonic (UT) inspection was performed on them at surface. Both sets of results (logs and surface inspection) were analyzed on the same logging track to give a comprehensive comparison of actual observation on surface vs the measurement by in-situ logging. Another multi-barrier corrosion and caliper log were run in the production casing to analyze their outcomes alongside older results. The final step was a comparison of all available data to create a broad well integrity profile. It was observed that the remaining production tubing metal thickness detected by electromagnetic tool (logs) and surface ultrasonic measurements were in good conformance (+/-10%). In the corrosion evaluation of the production casing, the electromagnetic tool matched extremely well with the caliper log results. This shows a large reliability of this technology to quantify corrosion in offset wells. The correlation of logs with surface inspection results across wells in the same reservoir did not indicate a strong presence of external corrosion. The study enables the management to make critical business decisions on utilizing the well stock for the future. This work is the first time a comprehensive and critical analysis on the electromagnetic thickness logging technology has been done, comparing their results of remaining wall thickness to various technologies in-situ and on surface. The analysis not only compares technology from various providers, but also mechanical vs electromagnetic measurements along with their respective advantages in quantifying well integrity assurance. The paper also gives an idea on the condition of L-80 tubulars under service for 30+ years.

External Corrosion Behavior of Steel/GFRP Composite Pipes in Harsh Conditions

In this study, we report on the corrosion behavior of hybrid steel/glass fiber-reinforced polymer (GFRP) composite pipes under harsh corrosive conditions for prolonged durations. Specimens were immersed in highly concentrated solutions of hydrochloric acid, sodium chloride, and sulfuric acid for durations up to one year. Detailed qualitative analysis using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and energy-dispersive X-ray spectroscopy (EDX) is presented. It is shown that the hybrid pipes have excellent corrosion resistance with a corrosion rate of less than 1% of the corrosion rate for conventional steel pipes. That low corrosion rate can be attributed to the formation of pores in the GFRP layer due to increased absorption and saturation moisture in the material with increased soaking time. This can be reduced or even prevented through a more controlled process for fabricating the protective layers. These promising results call for more utilization of GFRP protective layers in novel design concepts to control corrosion.

Fatigue detection and analysis of drilling tools based on metal magnetic memory method

With the vigorous development of offshore oil and gas resources in the world, underwater extended reach horizontal wells have been widely used. However, due to the complicated stress and serious corrosion of drill pipes in horizontal wells, drill pipes are vulnerable to damage. After a period of service at sea, some drill tools will be placed in coastal areas for a long time. The cumulative fatigue of drilling tools is not easy to master. In the past year or two, drilling tool failure has become more and more frequent. In order to evaluate the fatigue of drilling tools in different periods and master the quantitative fatigue of drilling tools, the metal magnetic memory method has its unique advantages in detecting the stress concentration and early damage of ferromagnetic materials. The self-developed metal magnetic memory detection device is used to detect the drilling tools in the drilling tool base. The results show that the gradient peak value and ladder are used to detect the drilling tools in the drilling tool base. The average degree can be used to classify the fatigue of drilling tools, and the metal magnetic memory method is more than sensitive to various defects of drilling tools, such as penetration, internal corrosion, external corrosion, wall thickness thinning, etc.

Complete Integrity Assessment of a Non-Piggable Multi-Diameter Cross Country Pipeline in a Network Shared by Multiple Electrically Continuous Parallel Pipelines

A complete Pipeline Integrity Management System is the need of the hour. Apart from keeping in mind the enormous environment concerns in this rapidly dwindling era of hydrocarbons, a successful pipeline owner always strives to profitably operate their precious assets. To operate a pipeline efficiently, a plan is required to maintain its health and increase the remaining life. Various types of pipelines pose various problems which the owner needs to resolve systematically and with a well-ordered approach. A similar challenge was faced by a refinery in India. The refinery has a design capacity to process 15 MMTPA of crude per annum. The imports and exports are carried out through the local Port Trust which is one of the deepest inner harbour on the west coast. Multiple pipelines run to and from the refinery and the port trust (approximate distance — 10 km). The subject pipeline in question currently transports Mixed Xylene (MX) from refinery to port. The pipeline has a diversified operating history with various other products being transferred in the past. However, the pipeline is used very scarcely. The problem posed by the subject pipeline was similar to what many other cross-country pipelines face — the pipeline was not piggable. Five (5) other parallel pipelines share the same right-of-way, all of which are piggable and have their integrity assessment performed via Intelligent Pigging on a planned basis. There was also a concern about collecting the most accurate data since the pipeline had not undergone an integrity assessment since its commissioning in 2001. However, it was yearly pressure tested to ensure integrity of the pipeline. Parallel pipelines pose a bigger challenge for obtaining accurate data for a particular pipeline amongst them. Keeping all this in mind, a complete integrity management was planned for the MX pipeline and thus concluded on performing a turnkey Direct Assessment (DA) program. The DA program included Internal Corrosion Direct Assessment (ICDA) to assess and manage the threats of internal corrosion, External Corrosion Direct Assessment (ECDA) for external corrosion threats and Stress Corrosion Cracking Direct Assessment (SCCDA) for determining susceptibility towards the threat of stress corrosion cracking on the pipeline. Utilization of latest technologies helped in adapting and overcoming the multiple problems faced by legacy technologies especially in difficult ROW conditions and complex pipeline networks, such as the MX pipeline. This paper provides an insight into how an operator can combine latest available technologies and deploy it in unison with the complete integrity management plan.

Predictive Maintenance Framework for Cathodic Protection Systems Using Data Analytics

In the quest to achieve sustainable pipeline operations and improve pipeline safety, effective corrosion control and improved maintenance paradigms are required. For underground pipelines, external corrosion prevention mechanisms include either a pipeline coating or impressed current cathodic protection (ICCP). For extensive pipeline networks, time-based preventative maintenance of ICCP units can degrade the CP system’s integrity between maintenance intervals since it can result in an undetected loss of CP (forced corrosion) or excessive supply of CP (pipeline wrapping disbondment). A conformance evaluation determines the CP system effectiveness to the CP pipe potentials criteria in the NACE SP0169-2013 CP standard for steel pipelines (as per intervals specified in the 49 CFR Part 192 statute). This paper presents a predictive maintenance framework based on the core function of the ICCP system (i.e., regulating the CP pipe potential according to the NACE SP0169-2013 operating window). The framework includes modeling and predicting the ICCP unit and the downstream test post (TP) state using historical CP data and machine learning techniques (regression and classification). The results are discussed for ICCP units operating either at steady state or with stray currents. This paper also presents a method to estimate the downstream TP’s CP pipe potential based on the multiple linear regression coefficients for the supplying ICCP unit. A maintenance matrix is presented to remedy the defined ICCP unit states, and the maintenance time suggestion is evaluated using survival analysis, cycle times, and time-series trend analysis.