Most Malaysian oil production is heavily reliant on gas lift. Aging assets experience declining lifting efficiencies due to depleting reservoir pressure and increase in water cut. This impact PETRONAS' capability to deliver national hydrocarbon production targets. New developments and further improvements to gas lift facilities are likely to erode the economic value of assets without even considering the potential time impact due to the complexity in delivering gas compression upgrades or gas import projects. PETRONAS' primary goal within Malaysia is to sustain production and maximize the remaining recoverable reserves. To realize this target it is widely acknowledged that the company must think differently. Alternatives to gas lift have been considered for rejuvenation of brownfield assets and development of marginal assets using a ‘fit for purpose' approach resulting in some relatively low Capital Expenditure (CAPEX)/Operating Expenditure (OPEX) solutions. One such method identified was Through Tubing Electrical Submersible Pumps - Cable Deployed (TTESP-CD). TTESP-CD technology is a game changer that can challenge the boundaries of traditional engineering with a truly rig-less deployment of an ESP system with full compliance to API/ISO requirements and demonstrating up to 70% cost savings over conventional offshore ESP installation methods. The TTESP-CD innovation helps in improving the asset value through gas prioritization, gas lift reallocation, flaring reduction and increase in lifting efficiency. TTESP-CD is also in line with the company digitalization concept due to the baseline data available from surface and downhole equipment. This technology has been declared a success through pilot deployment in an offshore field within the Sarawak Basin with an incremental gain of 250BOPD, 0.3MMSTB in reserves acceleration and 22 months run life as of Feb 2019. This has been a key step for building confidence in the wider application of the technology. Lessons learnt and best practices from the pilot implementation have been applied to ongoing and future projects and serve as a good foundation for further development of the technology. To date, approximately 20 candidates for the TTESP-CD application have been identified for replication in Malaysia within the next 2 years across 3 regions. There are various challenges faced when implementing this technology on aging offshore assets that was never designed for ESPs which include; space availability for deployment equipment and surface electrical equipment, power availability and distribution, instrumentation, data transmission, structural integrity and operational mind set. PETRONAS sees a bright future for TTESP-CD application and technology which includes layer to layer matrix dump flood, interim production and well unloading/DST well unloading.

Field D (offshore Sarawak, Malaysia) first production was in 2012 from three wells, with a second phase of development in 2017 with the drilling of four wells. Severe productivity decline was seen in five of the seven wells, and numerous studies were completed to narrow in on the root causes. Several production enhancement techniques were executed on Phase 1 and Phase 2 wells, where learnings and results will be further shared. Prior to the drilling of six additional wells in Phase 3 (2020), additional detailed lab studies were undertaken, and new strategies were implemeted based on this were applied with encouraging results. The majority of the wells have downhole pressure gauges (PDG), and coupled with frequent well test data, PTA, and Nodal Analysis modeling Productivity Index, permeability thickness (kH), and Skin are able to be tracked over time. By trending these different productivity indicators, it became clear that formation damage was occurring in several wells with varying degrees of severity based on the performance of the reservoir layer being produced. Various formation damage mechanisms were assessed (scale, wax, asphaltenes, drilling & completion damage, fines migration), and based on the initial study it was determined that fines migration was likely the major issue. Historically, no sand was observed on the surface where monthly sand count reported has always been <1 pound per thousand bbl (pptb) which was supported by geomechanics, and sand failure tendency studies completed during development phase of the field. Hence, six of the seven Phase 1 and 2 wells were completed with cased and perforated strategy with no downhole sand control, with the other well completed as a highly deviated open hole standalone completion. The productivity declines were only experienced in the cased and perforated completions, which had much lower gross completed interval and thus experienced higher velocities near the wellbore. The main production enhancement strategy applied to date has been re-perforation (8 re-perforation jobs), with varying degrees of productivity improvement and duration of sustainability. Solid propellant technology was applied in one of the well and clearing of the perforation tunnels via through-tubing dynamic underbalance technique in two wells was applied and no major improvement in sustained production impact was observed. An acid stimulation was recently pumped for the first time in one well and the assessment details will be shared, and results of the pumping will be shared in detail. At the time of the paper, no post production results were available. Prior to the drilling of six Phase 3 wells in 2020, detailed lab studies to look at the impact of various drilling muds were assessed, and learnings were incorporated in the mud program. Critical velocity studies were completed, and learnings from this work such as well ramp-up strategy and normalized maximum production rates have been added to the well-by-well production strategy. Based on Phase 3 production data to date, application of these new learnings has resulted in no major productivity decline seen. The learnings from D field would benefit other operators by sharing the lessons learned on assessment of formation damage mechanisms, the results of the different type of production enhancements applied, and the successful mitigation strategies for future wells (lab assessment, mud strategy change, and production strategies to prevent plugging due to fines migration).

Following the first pilot success of the truly rigless 3-1/2" tubing cable deployed ESP (TTESP-CD in offshore field of Sarawak Basin, PETRONAS has taken steps to further advance in the technology development and application through more replications within Sarawak and Malay Basin. PETRONAS had been looking into a strong business case for the TTESP-CD technology for a wider application throughout Malaysia region by looking at fields with strong/moderate water drive and low bubble point pressure besides having other limitations on the platform including the facilities reliability issues. TTESP-CD are to be applied widely in Malaysia with more flexibilities in design and improvement towards the subsurface equipment, installation equipment and procedures. With the challenges in the existing completion and production requirement for replications, based on the lesson learnt from the pilot implementation, multiple improvements to the system have been done including; 1) A High Rate Slim Pump with Flexible Application 2) Alignment Tool for Cable Hanger Orientation. With this in place, more opportunities identified for the candidate selection which improve the installation philosophy specifically in dual string applications and enhance the efficiency in installation procedures. Case studies of TTESP-CD replications in Malay & Sarawak Basin for Field T, Field B and Field P presenting the best case for TTESP-CD application with improvement to design, equipment and application. These will bring additional value to PETRONAS with estimated production gain of ∼1.5 KBD and up to 1.2 MMSTB reserves to be monetized with additional value saving of up to RM 6 Mill. Besides the subsurface challenges, aging offshore assets brings a lot of challenges, especially on the space availability, structural integrity, power availability and distribution, instrumentation and data transmission. This requires an integrated approach from multiple disciplines in delivering the studies as per required within the targeted timeframe.

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