This paper demonstrate a unique combination of techniques and equipment that enabled dynamic reservoir evaluation process using simplified Drill Stem Test (DST) string and completion accessories. The well testing was conducted on a shallow slanted offshore well, drilled into faulted reservoirs with multilayer and complex fluids environment. Key technical challenges to perform well testing includes designing a custom DST string to cater for the multilayer reservoir and articulating a surface well testing equipment that capable of efficient separation to ensure safe and environmental friendly disposal while having accurate flowrate measurements, to deliver good interpretable data given that the uncertainty and complexity of the formation and the well itself. During drilling campaign, contingency plan to mitigate against losses was implemented which had a significant impact on the well testing program. As such, uncertainty-based well test design and interpretation methodology was used to address this and to achieve well objectives. This involved numerical model analysis considering reservoir uncertainties and their interaction with each other, to identify which parameters can be interpret confidently and to indicate the test duration for the well testing program. Since the area is nearby to producing fields, several cases model based on reservoir pressure regime was also constructed during the design stage to tolerate flexibilities for the decision tree. The well testing was successfully conducted result from integrated approach to well test design and realtime data support throughout the operation along with innovative DST string design, customize completion accessories for multiple zones testing and adaptive intervention tools for highly deviated well. Matching with nearby wells were also conducted during monitoring to predict future pressure behaviour which allow for the duration of final build-up to be optimized. Given that Health, Safety and Environment (HSE) is the top of priority, an important aspect of the surface well testing package was the water treatment equipment to treat the produced water from reservoir before being discharge in order to guarantee safe environmental disposal. The well was successfully test at maximum flowrate 2,000bpd of oil and 20MMscf/d of gas with traces of produced water. Data gathered thru the Tubing Stem Test (TST) can used to interpret reservoir parameters and all the well testing objectives were successfully achieved despite the many challenges encountered during the drilling campaign and design stage. The end results may contradict traditional testing methods for pressure transient analysis, but hopefully this paper might create the opportunity to replicate TST as quick and effective reservoir evaluation in other parts of the world.
As part of well cost reduction initiative, screenless fracpack has been successfully applied in Field D in which gravelpack or fracpack have been the prevalent sand control completion methods. This paper discusses the first application of screenless fracpack in Malaysia with description on design process, implementation method, challenges in design and execution, production performance, and the recommended way forward. Typical gravel pack or fracpack would require installation of downhole screen and packer assemblies, followed by gravel pack or fracpack pumping. The associated cost ranges from USD 1 million to USD 2 million for a multi-zone well. However, screenless fracpack application eliminates the high-cost screen and packer assemblies. Perforations are made with vertically oriented 0-180 degree phasing (up and down) to maximize fracture alignment with perforations as well as to minimize potential sand production from the perforations without fracture. Subsequently, perforations and near wellbore matrix are treated with resin injection to consolidate near wellbore formation in ensuring good sand/fines control in formation that is not fractured. Hydraulic fracturing utilizes tip screen out method to create short fracture length and wide fracture width to maximize dimensionless fracture conductivity. Proppant can be resin coated or treated with network of fibers to control proppant flowback in absence of downhole screen assemblies. All planned procedures have been successfully conducted. Perforations were made in a short interval i.e. about 2m in length with limited entry 4 SPF/ 0-180 degree phasing. Dynamic underbalance technique was incorporated to maximize open perforations effectively. Resin injection plan was dropped due to low permeability and low injectivity. Resin squeeze into a tight formation can end with either incomplete resin and overflush injection, or fracturing with the viscous resin, either of which would damage the formation. A highly conductive fracture has been created with tip screen out. Nolte Smith log-log plot showed a unit slope, an indication of tip screen out. Proppant flowback control was obtained with resin coated proppant. Post screenless fracturing, the well was carefully unloaded and cleaned. Well production showed good productivity and effective sand control. Currently, other fields are being studied and considered for the same application. Screenless fracpack is applied for the first time in a field offshore Malaysia. It is a bold step change whereby gravelpack or fracpack are commonly used as sand control. The application was driven by well cost reduction effort and the application is currently considered for replication in other fields. The benefit of the new method is not only the well cost savings by elimination of screen and packer assemblies, but it also provides full bore access and simpler well interventions. This application helps in brownfield and marginal field development whereby small reserves may negatively project economics due to high cost for gravelpack or fracpack installation.
This paper presents the organic and inorganic scale depositional issues in Field P, a marginal oilfield located offshore Peninsular Malaysia. Routine well interventions such as running pressure surveys, performing zone-switches and gaslift valve change-outs is not a straight-forward affair in Field P. The field not only experiences severe wax-buildups downhole - as field water production continues to increase, calcium carbonate scale has in recent years been precipitating along the tubing wall of most wells, forming an organic plus inorganic agglomeration which is a rare occurrence and not as easily removed as with a conventional solvent or acid soaking job; thus preventing wireline entry for production surveillance and enhancement activities. Several mechanical, chemical and even combination techniques have been deployed with varied levels of success at Field P, which produces waxy crude from a small and unmanned platform. Facilities constraints (i.e. small deckspace and limited crane lifting capacity), a low oil price environment and high cost for effective wax and scale removal all contribute to the list of challenges in arresting production decline and maintaining a healthy cashflow for an asset which is nearing the end of its economic life. This paper describes the different wax and scale removal and inhibition methods tested in Field P, challenges in implementation, treatment effectiveness, and lessons learnt which can be used as reference for asset teams facing similar issues. The study and recommendation to implement an optimal scale management plan is shared.
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