Most of PETRONAS fields in Malaysia have been producing for more than 20 years. At this advanced stage of depletion, reservoir driving forces are low. Organic deposition, particularly in the near-and-around well bore region and in production tubing, can further reduce the production of oil by restricting the flow passage from reservoir to wellbore. A study to address this issue with a view to rejuvenate the problem wells through laboratory analysis & pilot field implementation was conducted. A unique thermo-chemical system has been developed as an effective tool for 1:Removing the organic deposits near-and-around wellbore and production tubing, henceEnhancing the production from the treated wells. The two components of the system are injected simultaneously into the wellbore through production tubing. Upon mixing, both components will produce heat and reaction products. The heat generated capable to melt and dislodge the organic deposits. While, the reaction products will act as an effective solvents and surfactants for dispersion of organic species. The objective of this paper is to present the result of 4 wells treated by the thermo-chemical system. Well selection criteria based on production profile and well history is described. The implementation technique and a post treatment production gain are also highlighted. INTRODUCTION Crude oil is a complex mixture of various hydrocarbon components. Under reservoir conditions of high temperature and pressure, the crude oil components exist in two phases (liquid and gaseous) under thermodynamic equilibrium with connate water attained over geological times. Heavy hydrocarbon components such as asphaltenes, resins and waxes, which at normal surface conditions are solids, exist in solution, either colloidal or disperse form, in liquid hydrocarbons. Similarly, light hydrocarbons which are in gaseous form under normal surface conditions, exist in solution and vapour forms under equilibrium with each other. When a well is put on production, the produced liquid and gaseous phases (water, oil and gas) are subjected to lowering temperature and pressure along production pathway and as such pass through a continuum of dynamic phase equilibrium. As a result, oil soluble solids (asphaltenes, resins and waxes), water soluble solids (scales) and soluble gaseous start separating out from the produced oil. These separated/precipitated organic solids under favourable hydrodynamic conditions have the ability to agglomerate, grow in size and diffuse from bulk to interphases (rock surfaces and pipe walls) and form deposits. The produced formation fines (sand, silt, clay etc), water borne scales and fine corrosion product can get oil wetted and act as excellent nuclei for the initiation and growth of organic deposit particularly waxes. Therefore, the actual oilfield deposits are composed of organic solids, scales, formation fines and trapped oil. The organic deposit can be predominantly parrafinic or asphaltenic in nature depending upon the nature of crude oil, change of temperature and pressure equilibrium, production rate, etc. The deposition can take place at all locations along the production pathway viz-a-vis around wellbores, in production tubings, surface facilities, flowlines, pipelines and storage tanks. Deposits around wellbore (causes formation gdamage reflected by high skin for the well) and in production tubing, adversely effect the well productivity.
Optimization of mature fields in maximizing the hydrocarbon recovery has been a major concern for exploration and production companies including PETRONAS Carigali Sdn. Bhd (PCSB). CC is a brown field, situated in south central region of the DD Province of the Sarawak Basin.Since CC field has marginal reserves, an effort to enhance the production was initiated with the objective of economically boosting the remaining reserves.The proven Low Pressure System (LPS) that is widely implemented across Petronas operating fields has benefited CC in optimizing the production by lowering the existing surface back pressure. However, the challenges faced in implementing the system in CC are platform surface constraintand unmanned-operation-at-night philosophy.
BY, an offshore oil field discovered in 1976, has been in production since 1984. Several production enhancement activities were continuously conducted throughout the production life of the field. This includes surveillance works to arrest the production decline and enhance the oil recovery. A systematic investigation showed that a few wells were having anomalous high water production despite being located at the crestal area of the reservoir. Further investigations revealed that poor cement bonding behind the casing was the main cause of high water production in the up-dip wells. With this new information, an evaluation of the remaining reserves was carried to justify any remedial well work required to reactivate the wells. A coiled tubing cement squeeze job was identified at BY field to unlock the well potential of the watered out well located at the crest of the reservoir. The well, WELL-X has been idle for over 20 years due to high watercut. After a successful job execution, the well was able to flow with more than 1000 STB/D at 0% water cut. This has opened up more opportunities for idle well reactivation of other idle wells with similar high water cut due to cement channelling issues behind casing. This paper presents an established workflow and optimization cycle adopted in BY highlighting the methodologies/techniques used to identify potential production opportunities that may have been overlooked in a brownfield and a recommendation on the way forward. The systematic workflow applied displayed success in a well using rigless intervention and has achieved economic return in a short time.
As of early 2017, PETRONAS has approximately 40% of aging platforms & pipelines that aged more than 30 years. As a party to UNCLOS, Malaysia is legally bound to undertake Decommissioning of its asset. Internally, apart from PETRONAS’ existing Procedure and Guideline for Upstream Activities (PPGUA) that spell out the recommended decommissioning principles, PETRONAS has devised a new set of decommissioning review process, known as Abandonment Review (AR) to ensure PETRONAS get the optimum levels of assurance its require from the operator/contractor. The deliberation of every decom project application is according to the type of scope of works which covers wells plug & abandon, pipeline/floaters or integrated facilities. Following the downturn in crude oil prices and major decline in oil production for some of its fields, PETRONAS had to further evaluate and finally decided to decommission one of its Small Field Risk Service Contract (SFRSC) field, specifically Kapal Field. Upon PETRONAS’ review & approval process completed, execution phase commenced with the least complicated scope of work, which consist of Plug & Abandon (P&A) of 4 wells, detachment of wellbay support structure (WSS), retrieval of mooring chains, anchors and flexible pipeline, and relocation of MOPU for warm stack/cold stack purposes. However, during Project Risk Assessment exercise, relocation of MOPU was identified as one of the critical path as it involves integrity of the existing MOP and as such posed a high risk to the whole cost and schedule of the project. Since decommissioning of upstream facility consider as a niche subject in Malaysia, educating of various internal and external stakeholders was required in order to establish the key steps for the decommissioning execution. Liaising with related state agencies was done through Exclusive Economic Zone sitting, with Petroleum Safety Unit's (PSU) as the secretariat. PSU is one of the unit under Ministry of Domestic Trade, Cooperative and Consumerism (MDTCC) which responsible in coordinating the policies, licensing, regulations and activities related to the safety of petroleum, petrochemical and gas industry in Malaysia. There were plenty of great experiences and important lessons that PETRONAS learned in this project which PETRONAS thought worth to share with the industry. PETRONAS believes that through each successive failure in what we're doing, our values were reshaped. Even though this decommissioning activity was a schedule-driven project, cost optimization always becomes the key condition for making project management decisions. Not to mention on PETRONAS’ aspirations to contributes to sustainable development by delivering economic, social and environmental benefits for all stakeholders, collaboration and Memorandum of Understanding (MOU) achieved between PETRONAS and Department of Fisheries (DoF) in Rig-to-Reef Program had opened up a new perspective on how PETRONAS’ decommissioning activities can contribute towards its corporate social responsibility (CSR) program.
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