Platforms with limited crane capacities and restricted space in which to set up the necessary well intervention equipment are challenges that the industry is facing increasingly in offshore environments. Operators are having to either compromise on operational efficiency and certainty through the use of memory based slickline conveyance applications (e.g. slickline perforating without real time correlation) or are having to rely on more costly solutions utilizing a multitude of equipment and leveraging workover rigs in order to accomplish their intervention campaigns. Real time slickline’s light, minimal foot print and modular make up coupled with its digital telemetry enablement allows operators to access wells and perform conventional slickline operations, plus perforating, plug setting and production logging, all with downhole in-situ information available on surface in real time, bringing huge operational efficiencies as well as reducing considerably the risks and uncertainties of the intervention programs being undertaken. Interventions executed using real time slickline have proven to be a safer, more efficient and more cost effective way to conduct operations by having full realtime control of its downhole tools and periphery sensors. It reduces the associated risks of having to mobilize and switch between electric line and slickline units, equipment and personnel in the cases where the scope of the intervention programs can be fully covered by real time slickline’s capabilities. Furthermore, its minimal weight and footprint enables intervention operations where space and crane capacities make slickline the only choice of conveyance.

Angsi X06L was a firm candidate for a workover targeted to be re-completed in April 2010. This well was diagnosed with a severe downhole control line leak, causing the well to be shut in and led to Angsi field deferment of 800 barrels oil per day. PETRONAS Carigali Sdn Bhd (PCSB) had already attempted to rectify this problem by injecting pressure activated sealant a few times but failed in its efforts. Based on the diagnostic done, the leak rate was more than 1.5L/min, way beyond the selected activated sealant capability. The next possible option was to install a storm choke or ambient valve but unfortunately this method was prohibited by PETRONAS. Late April 2009, PCSB embarked on a technical feasibility study using high strength duplex alloy to permanently replace current surface control sub-surface safety valve's (SCSSV) control line. A complex operation that involves multiple services was designed and executed which comprised permanent abandonment of the old hydraulic control line, SCSSV flapper locked open and many more multifarious steps. With the use of this new innovative application, savings of about USD 7 million from the procurement cost of well completion, rig, barge and associated services was realized. This paper will discuss project background, technical feasibility study, work designs, jobs execution and lessons learnt for such an operation in West Malaysia.

Objectives/Scope: When drilling a micro fractured formation, the fluid differential pressure for wellbore support can be lost and the unsupported formation may fail, causing losses, pack-off and instability. This may be minimized or resolved if the zones of pre-existing fractures are known and the trajectory is optimized to avoid them. In the Malay Basin, one structure of interest has undergone several periods of stress and faulting, at times, strike-slip in nature. Wrench faults in the area are causing compression and extension. This strain causes micro fractures and voids to be generated. The formation has a secondary porosity but seismic resolution does not allow the pre-existing fractures to be seen. By using a technique known as Geomechanical Forward Modelling (GFM), it is possible to determine natural fracture distribution and avoid these zones, thereby decreasing the risk of encountering instability caused by secondary porosity. The problems of borehole instability encountered in the area are demonstrated in wells, A1, A2 and A3. The most problematic well was A3. It had many incidents of pack off causing side tracks. In each case, the hole condition was better on side-tracks made higher up the well. It was considered that there is a 3 dimensional extent to the presence of micro fractures. The fracture intensity may have a vertical as well as areal extent. Sometimes wells crossing above or below a zone are not as difficult as through it. On wells that experienced pack off, cavings at the shaker had an abundance of linear breaks oblique to shale bedding surfaces and suggests the probability of pre-existing fractures. Pre-existing fractures were also seen on image logs. During planning for an appraisal well, zones with lower plastic shear strain were identified to the North and West of the planned well trajectory by applying GFM. The plastic shear strain profile along the planned trajectory suggested that the target depth will intersect a potential fractured zone. By moving the surface location by only 500 meters, the chances of encountering pre-existing fractures was significantly diminished. By applying Geomechanical Forward Modelling, (GFM), it is possible to determine distribution and possible locations of secondary fractures, too small to be determined from seismic. This allows for the selection of well trajectories to avoid these naturally fractured zones, thereby decreasing the risk of encountering instability from secondary porosity (pre-existing shear fractures).

BNX field is a mature oil field with complex wells targeting multiple reservoirs across the field. The introduction of an Enhanced Oil Recovery (EOR) project has set a new challenge on determining the integrity of aging wells. In the past, comprehensive downhole casing integrity testing was rarely done with the exception of conventional pressure integrity checks. Such methods may have limited effectiveness in analyzing wells with multiple strings and complex completion configuration, and cannot precisely locate or quantify the magnitude of metal loss. Convention is to run a Multi-fingered caliper inspection tool to evaluate the single tubing inner metal loss, but again this has limited value as it could not measure tubing thickness or more importantly the condition of the casing behind the tubing. A solution was needed that could allow the evaluation of tubing and casing to be done offline and simutaniously. An innovative approach with a combination of slim-hole ultrasonic borehole imaging tool and electromagnetic imaging tool is deployed to provide a new insight in the casing integrity evaluation in the field of study. The idea being that the borehole imager would accurately describe the tubing string while the electromagnetic tool would describe the total metal, both tubing and casing, subtracting the tubing thickness from the total metal measured would then leave an accurate measurement of the casing thickness. Three well candidates were identified, each well was planned for a sidetrack, but before moving a rig onto these old wells the team wanted to know if the 9 5/8? casing was in good enough condition to use. And for the first time, the thickness of multiples strings up to 13.375 inch casing was evaluated simultaneously utilizing a low frequency electromagnetic and a high resolution ultrasonic measurement. The ultrasonic tool provides comprehensive metal loss evaluation for inner most string while the electromagnetic tool provided the total metal thickness of both strings. The combined interpretation of these two through-tubing evaluation outputs provides a viable technique to evaluate metal loss profile for first two strings under study without the need to pull the inner most string. The overall casing evaluation operation is further optimized by the maiden deployment of an e-line light weight unit. The successful application of this newly integrated casing integrity evaluation technology has greatly reduced the intervention related risks, costs and time. The case study presented will serve as the critical pilot to extend the same workflow to other wells across the field. In addition it paves the way for the next generaltion of EM and slim ultrasonic tools discussed at the end of the paper.