A previous attempt to drill an exploration well in ultra-deepwater in the GoM did not reach its objective due to an inability to maintain a Water Based Mud system light enough to maintain circulation. For the next round of exploration drilling, a system that allowed dynamic management of Annular Friction Loss (AFL) was required in order to stay within the narrow margin between pore and fracture pressure gradients.Conventional Rotating Control Device (RCD) based Constant Bottom Hole Pressure (CBHP) management systems were not suitable, as no drilling fluid light enough to manage the AFL with an added backpressure could be applied for this campaign.A "Controlled Annular Mud Level" type DGD system was successfully applied on this well in 2260 m water depth. This method compensates for the annular friction pressure by reducing the riser level according to the circulation pump rate. The system was also used to manage downhole pressure for cementing operations to mitigate losses and ensure good cement integrity with full returns during the cementing operation.The riser level was decided in the drilling program and adjusted according to PressureWhileDrilling (PWD) Readings. It could also be demonstrated that lowering the riser level increased ROP, whilst raising it again decreased ROP. The sensitivity for kick detection was greatly improved as the effect of rig motion on surface volumes was eliminated.The paper presents the project approach to deliver results and the technology applied. Results achieved on this well will be discussed, and how to further enhance the technology to other projects and increase the operational envelope of the system.

The Main Sultanat of Oman Gas Field is comprised of two deep tight gas clastic reservoirs, separated by thick shale layer, and has been on production since 1999. These reservoirs are encountered at depth ranges of 14,000 - 17,000 ft and the top reservoir is a rich gas condensate followed by a lean gas for the lower reservoir. Permeability is in the range of 0.01 to 10 mD, porosities of 1 % to 14% and this field being a swing producer, actual production is in the range of 700 - 1,000 MMsfcd. To ensure achieving a maximum value, from such complex reservoirs, the field has gone through several development stages. The first stage has focused mainly on appraisal and development wells to obtain better understanding of well and reservoir performance and further data acquisition for better reservoir characterisation. The second stage of the Field Development Plan (FDP), in 2005, was an update of the FDP reflecting all the information that have become available since the commission of the field as well as the production performance gained from the previous 5 years of production. Further optimization of total number of wells, better prediction of the field performance and firming up the first stage of depletion compression were the key elements of the FDP update. Hence, first stage depletion compression plant was pursued and commissioned in 2010. In addition, velocity strings from 51/2" to 27/8", for maximum utilisation of low producing wells, were evaluated and more appraisals activities, for further scope maturation, were assigned. The third stage of the FDP update has been completed. The key objectives were to validate the previous FDP, in particular, wells and reservoir performance as a result of stage-1 depletion compression. Besides, phase-2 depletion compression was proposed and the remaining development drilling were re-evaluated, optimised and confirmed. Furthermore, a plan to mature contingency reserves, from poor reservoir intervals, was initiated and associated studies, such as geomechanical models and fracturing optimisation were performed. In this paper, a case study of developing a complex and tight deep gas reservoir will be discussed. The experience of applying phase approach and associated value will be shared and how the multidisciplinary team came up with the best Field Development Plan taking into consideration the different challenges and options taken by every discipline to put the best development strategy to get the optimum ultimate recovery from the field.

Straits of Malacca Exploration Campaign marks PETRONAS' first oil/gas well drilling in the region of West Coast of Peninsular Malaysia. Three (3) exploration wells were drilled in a period of four (4) months. This paper will highlight the challenges, lessons learnt and key to success of this fast track drilling campaign in a new region of operation.The team which was entrusted with the mission to drive PETRONAS' quest of oil and gas in this new region were then given six (6) months to deliver the first well out of three (3) exploration wells. Apart from the uphill task to set up staging base and logistics support in the West Coast of Peninsular Malaysia, the team faced challenges of drilling in one of the world's busiest shipping lane. Navigational safety is one of the main concern here. Besides, two (2) of the three (3) wells were located close area where sea robberies and hijacking were rampant. In terms of drilling operation, two (2) of the wells were exposed to the risk of total losses. This paper will share the approaches taken by the project team in overcoming challenges in three (3) main areas -(1) logistics; (2) navigational and offshore safety and security; and (3) well engineering.Although faced with numerous challenges together with limitation of time and resources, the project team has managed to deliver all the three (3) wells successfully, meeting all the geological objectives within Authorisation For Expenditure (AFE) cost. On top of that, the drilling campaign was completed with zero Lost Time Incident (LTI) and zero accident. Another notable success in this project is setting up the modus operandi in a new region of drilling within six (6) months. Due to the fast track nature of this campaign, first of the three (3) wells was spudded concurrently with 3D seismic interpretation by taking the risk of relying on 2D seismic data. Halfway through the well construction, Well #1 (Well A) was re-sanctioned based on the findings while drilling and latest 3D seismic data received. Target depth of the well was revised to 3130m TVDSS from initial 2100m TVDSS. Despite all the challenges, the drilling team managed to complete drilling operation of three (3) wells ahead of time by 11 days in total.Apart from engineering and logistics challenges, this paper will share the experience of drilling in one of the busiest shipping lanes in the world. Lessons learnt and key success factors of this fast track exploration drilling campaign will be beneficial to all oil and gas (O&G) operators, especially to those planning to operate in the Straits of Malacca or any other similar regions in the world.

Condensate stabilizers at PDO Saih Rawl Central Processing Plant experienced severe pre-mature flooding causing process upsets and Operational difficulties. Conventional steady state simulations and tray hydraulics could not suggest actual causes. The purpose of the proposed paper is to present the methods followed in analyzing the flooding issue and identified solutions. Initially, the flooding issue was analyzed by carrying out steady state process simulation with latest feed composition and tray adequacy checks in consultation with the tray supplier. The study concluded the existing hardware is adequate, jet flooding limit and down comer flooding levels well within acceptable limits. The study recommended only few adjustments in Operating conditions to resolve the issue. As part of verification, alternate tray suppliers were also approached to carry out tray hydraulic checks and found no concerns. Subsequently, the column was subjected to gamma ray scan during normal operation and a scanning was repeated after simulating a flooding inside the column. Coupled with gamma ray scanning results, a tray by tray by simulation was carried out to ascertain the flooding the phenomena. Gamma ray scan revealed the condition of the column internals, liquid heights and froth level during normal operation as well as during simulated upset conditions. Even though the trays were in good conditions, bottom few trays showed higher liquid height during normal operation itself. Along with the results from Gamma ray scanning, process simulation results and investigation of Operating conditions revealed the possible reasons for the flooding issue. The study predicted a temperature dip in few trays and further rise somewhere near the column top, which is unusual for a distillation column. This is the resultant of different feed ratios from the original design and one of the feed to the column is estimated to be below 5 °C, which is too cold compared to column profile. Based on the results, options were developed to alleviate the flooding issue without compromising the production capabilities of the column profile. The nature of flooding experienced inside the column handling different feeds and large variation in temperatures is unique with the condensate stabilizers. Conventional full column steady state simulation and tray sizing were not adequate for investigating problem. It needed, gamma ray scanning while the column is in normal operation and during simulated flooding condition.