Shallow casing corrosion in onshore wells is a well-known phenomenon throughout the Arabian Peninsula. It happens when the carbon steel is exposed to corrosive environment (including moisture and oxygen) due to insufficient barrier protection and isolation. The issue requires periodical casing excavation and inspection which are time-consuming operations with different teams involved. This document describes successful field validation of the alternative cost-efficient method of casing inspection using corrosion logging technology. The method of individual electromagnetic metal loss logging for 3 barriers became recently available. It is electromagnetic-based technology which was modified to be able to provide multiple barrier evaluation. 3 wells were selected for trial logging and later were excavated to compare the logging results with actual findings (physical check). Results of the trial test confirmed applicability of this costefficient technology for Company Surface Casing Inspection. The new method allows extending casing inspection to unlimited depth with less time required and less risks associated. The opportunity to evaluate conditions of all three barriers without retrieving the tubing gives a lot of benefits for the entire Well Integrity Management process; it may include actual corrosion rate measurements of all effective barriers, SAP (Sustained Annulus Pressure) investigations, and risk assessments. Field validation of this technology had a positive impact on Operator's Well Integrity process, giving more options for proactive Well Integrity Management and resulting in total cost reduction and improved HSE (Health, Safety and Environment) performance. Additionally, it helped to identify a serious gap in the existing conventional process of Surface Casing Inspection. This document presents the results of technology validation performed in the third barrier of a producing well in real field conditions. Additionally, it contains specific recommendations for other areas of application of this technology for maximum benefits, like three-barrier evaluation prior to workover and multiple barrier time lapse corrosion monitoring.

During normal rig workover operations, once the old completion is retrieved, corrosion log is being executed to check the condition of the casing and/or liner as one of the means to establish a way forward. Decision can be made easily in case of pipe found completely corroded or absolutely intact. However, such clear scenarios are not always the case and the decision making takes significant time, specially if corrosion log results are received at night time or during the week end. It may become a subject of hot discussion between involved stakeholders, trying to find a right balance between safety and operations. Therefore Gas Development Operations Subsurface Team of ADNOC Onshore requested Technical Center Well Integrity Team to identify clear criteria in advance, to save rig time and improve business performance and decision making process. Based on this request Technical Center developed a strategy of predefined well integrity criteria's that are being successfully used now, saving rig time during workover and avoiding conflicts between teams in questionable situations. The method is based on several factors: Maximum Allowable Annulus Surface Pressure (MAASP) calculation as per Norsok D10 standard, application of Double Barrier concept for Secondary Well Barrier Envelope, sensitivity analysis based on MAASP degradation and remained wall thickness of casing and/or liner. This method has already been successfully implemented in several wells during workover operations saving time for decision making. It is planned to be included in the next release of corporate procedures. Method, explained in this paper can be used as a guideline by all petroleum engineers, drilling engineers, well integrity engineers and petrophysicists who are involved in workover operations, helping them to improve decision making process based on the results of the casing corrosion logs. In addition, the subject of well life prediction and well life extension in standard Company well design is covered, with focus on safety during workover operations.

Over the ages of the well drilling history, primary and remedial cementing remains one of the most challenging activities with direct effect on the well life and well integrity status. This paper is based on the actual lessons learned and latest best practices in zonal isolation of Company fields developed according to business requirements during drilling and workover operations. It covers the aspects of primary cementing in two main types of casing design, and describes major challenges associated. Authors tried to define a clear criteria on what can be considered as the minimum acceptable zonal isolation, what are the issues associated with its evaluation, what needs to be done in order to meet those criteria. Additionally, there is an analysis done on the direct impact of the cementing job on the well life. Particularly, the focus is made on well integrity related issues and remedial solutions to cure them based on successful case histories. The paper answers on many questions related to the consequences of the poor cement isolation (up to well control incidents), as an actual lessons learned collected over the 60 years of operation. The impact of the casing design on the well integrity status is analyzed based on the results of wellhead pressure monitoring of around 4,000 wells. It includes revision and analysis of cement evaluation logs of wells with behind casing communication (sustained pressure in "B" annulus) along with the challenges associated with the diagnostic investigations of the leak source. Various cementing remedial techniques are described with pros and cons analysis and actual case histories including results of post-job wellhead pressure monitoring. The subject of swelling phenomena of soft shale formations and its effect on acoustic based tools for cement bond evaluation is touched as well. Finally, the paper contains interesting results of the recent corrosion logging campaign that reveals a correlation between casing condition and casing design.

Well double barrier envelope policy is a common industry practice and main philosophy of well integrity discipline. It is well-explained in well integrity related international standards: API RP90 (1 & 2), Norsok D10, ISO 16530 (1 & 2). It states that all wells with positive pressure at surface capable to flow naturally should have primary and secondary barrier envelope. Primary barrier envelope consists of well equipment which is continuously in direct contact with hydrocarbon and is pressurized. In case primary barrier failure (leak through the tubing, packer, or other completion equipment element), secondary barrier envelope is the one that holds the pressure and prevents further escalation of the incident outside of well boundaries. The content of this paper is related to such kind of wells that comply to the double barrier policy and are equipped with production packers. Conventional process of curing packer leak is to re-complete the well during rig intervention – the workover. During this process old completion is retrieved and new completion is installed. This operation can be repeated multiple times. Failure of any element of the primary barrier envelope results in the sustainable pressure in annulus "A" – SAP pressure. Such SAP wells is a violation from double well barrier policy and create a hazardous situation.

Objectives/Scope The development of Abu Dhabi's sour gas is not without its challenges. Deep drilling in some fields presents its own set of difficulties due to high temp and pressures coupled with +30% H2S and +10% CO2. Handling of these corrosive reservoir fluids both while drilling and then testing, requires deploying advanced technology to meet the specific requirements of these reservoirs, along with the infrastructure necessary to handle the toxic and corrosive products while testing in a brown field safely. Methods, Procedures, Process Developing local sour gas production is seen as the answer to resolve the ever growing energy needs for UAE but the technical requirements for the project is stretching the limits of the industry. Results, Observations, Conclusions What did we do different: Developed and implemented specific HSE procedures and SIMOPS due to close proximity with major populated facilities which could not be shut-down during the testing period. Conducted multiple audits and drills with the local authorities including Civil Defense and local Police. Additional 3rd part supervision was provided to ensure all personal are complying with the policy and procedures developed. Installed 2 green burners and 2 vertical 90 ft flare stacks at 180 degrees. This was to cater for the changing wind directions for continuous operations and as back ups. CCTV monitoring for green burners / flare stacks was conducted although this was a rigless operation 3 circles of H2S detectors and sensors were placed around the testing area and the flare stakes and green burners to detect any H2S gas. (Covering all 360° directions). Blowdown/Depressurization valve was installed at separator, storage tanks apart from Automatic and manual shutdown system upon H2S detection Installed Optic Fiber cable from wellhead to the main control room for monitoring purposes All piping connections used were flange-to-flange as welded joints could have caused stress cracking on the weak points For Sour well operation, used fully cladded X-mass tree & Inconel well completion Considered setting of compatible TTBP (Thru Tubing Bridge Plug) for staked reservoirs zonal isolation Instead of coil tubing cement plug for accurate depth calculations. Arranged Special chemical for any scale cleanout for handling of elemental Sulphur. Arab zones were stimulated with specialized acid recipe developed exclusively for this temperature, pressure and sour conditions downhole. Bottom hole measurements were recorded successfully and all the necessary data was acquired. Novel/Additive Information This paper highlights the major challenges identified and mitigated to test and produce the highly sour HPHT gas during the appraisal program complying with ADNOC 100% HSE in a brown field without disturbing the other major operations being performed in the vicinity.