Dealing with mature offshore oilfield has complicated problems both surface and subsurface. In the reservoir condition high water cut wells make some bad impact in the production stages. Liquid handling facilities, tubing pipeline erosion, broken sand control, and high power consumption are several problem caused by high water cut wells. WW is an offshore oil field which has developed since 1990s with OOIP 758 MMBO. This reservoir was divided into several layer, 33 series is depleted reservoir with water injection since year 2000s (RF 23%) and 35 Series has strong water drive as its driving mechanism (RF 56%). Almost 85% of the oil wells is producing with water cut more than 97%. Increasing water cut or even watered out phenomenon was frequently happen during production stage, some of this problem was happen after well intervention such as after pump replacement. This paper will show the successful case of decreasing water cut significantly from WW D-29, WW H-12, II A-22. Laboratory test was firstly done to check the compatibility test of the rock with modified completion fluid. This chemical was mainly works as phase change water control and oil stabilize well for completion fluid. It was pumped simultaneously with regular completion fluid (filtered drill water and additives). Killing well was mandatory procedure when shut in wells will be repaired. GGR team supported by Production and Workover Team did integrated study to choose the chemical and well selection based on some criteria. WW D-29, WW H-12, and II A-22 are wells which have implemented modified completion fluid treatment. Those wells are produced from sandstone reservoir and drilled more than 10 years ago. During production period, water cut was significantly jumped due to several reason, such as pump replacement job, re-start up after the well trip off, etc. The result of the project were very excellent, WW D-29 (from 98% to 86%, gain +/− 180 bopd), WW H-12 (from 80% to 40%, gain +/− 250 bopd) and II A-22 (96% to 75%, gain +/− 130 bopd). These result give a lot of impact of increasing oil production in WW Field. This paper will elaborate how to solve the problem in offshore mature oil field special case for high water cut wells using modification of completion fluid treatment. We have succeeded increasing oil reserves.
In recent years the Industry are busy talking about the subject of mature field development, lots of opportunity and approaches has been applied to enhanced reserves and production, in the other hand efficiency and technology also can be the answer of the subject, big volume of data at high frequency produced every second, searching relevant information from those data are quite complex and time consuming, not to mention processing huge data volume for many particular solution, it is complicating the decision making process. The objective of this paper is addressing the process and technical challenges in building digital oil field platform at offshore mature asset to speed up the decision making and make operation activities more efficient. The design of the workflows and business processes are tailored to accommodate any kind of input across all the disciplines from reservoir, production, drilling and completion to produce output as desired. The early stage process of building digital oil field system starts from data utilization that produced by downhole sensors, it is attached with Electric Submersible Pump that installed at all wells. The data transformed into information for real-time production monitoring & optimization, these workflows allow production enhancement by continuous monitoring of production parameters such as pressure, temperature, flow rates, choke settings and target. Analysis of these parameters carried out using trend, in case of anomalies happens in the process, the system will provide the information and possible solution. Digital Oil Field technology can be a game changer for the mature field development in the future. Integration of technology, process and people together to achieve financial objective is the major initiative of digital project, but applying digital technology is easier said than done as our companies are finding out, in our case we faced several difficulties that need time and complex algorithm to find the solution. But this early stage of digital oil field will answer the challenges in managing offshore mature asset efficiently, because it will reduce downtime, optimize production, and reduce cost. The future development of digital oil field in SES Block will allow all parties to grab the information in present time and also the forecast prediction of asset performance in the future. SES Block is a mature oil field that has produced for more than 50 years, peak production rate almost reached 250,000 BOPD in 1991, while current production rate around 30,000 BOPD. One of the major problems in this asset is the excessive use of Electric Submersible Pump that generates high operating cost, this is the reason why efficiency during daily operation process using digital oil field application is smart answer to reduce cost and optimize company profit.
Located offshore South East Sumatera Indonesia, C-SY field is a structural trap with 4-ways dip closure and multiple reservoir targets with excellent rock properties, considered a marginal field and currently idle for 8 years. Challenges faced in reactivating C-SY field are high investments compare to other well service proposal and have limited reserves. The objective of this paper is to revive idle marginal offshore brownfield C-SY by increasing value of reserves and economics value. In order to do so, all prospects within C-SY area need to be assesed, including exploration prospects with high geological chance factor. The evaluation process worked simultaneously by exploitation and exploration team. The exploitation team worked on re-estimate OOIP and reserves of existing reservoir by structural interpretation, reservoir characterization analysis using attributes, Decline Curve Analysis & Material Balance Analysis. While the exploration team worked on finding other reservoir prospects by doing prospect identification from 3D seismic analysis, structural play analysis, closure identification and migration pathway from kitchen to prospect area, calculate OOIP. Result from both teams were combined to estimate reservoir behavior and production forecast. The next step of evaluation was to create multiple cases of possibilities and calculate the economics to find the best and possible case with minimum calculated risk. Collaboration between Exploitation and Exploration has lifted the value of C-SY idle marginal brown field, new structure has been found with promising reserves and initial production. Initial production C-SY field after the collaboration is 1,200 BOPD from previously 150 BOPD, while remaining reserves increase 3 times higher up to block expiration contract in 2038. Developing marginal offshore mature asset is a risky business, especially considering high volatility in oil prices. Collaboration and technology are vital to escalate the economic value and achieve higher recovery factors. Application of the multidisciplinary methods was considered as an appropriate way to approach and manage a complex marginal mature field redevelopment.
This paper describes an efficient approach to evaluate waterflood connectivity performance in complex compartmentalized reservoir, the objectives are to increase the oil production performance and manage mature fields effectively, and also to enhance ultimate recovery in the long run. It is also very useful to get better understanding of detail reservoir characterization, reservoir internal architecture, reservoir distribution, pressure monitoring and subsequent water flood sweep pattern efficiency. Multi-disciplinary methods applied to maximizing all of data and create strong analysis. The first phase is deep sub-surface analysis in property distribution, simultaneous inversion, 4D time lapse seismic and sweep pattern analysis, those analysis have been done to get comprehensive interpretation of reservoir characterization and waterflood monitoring. The second phase is tracer injection, we implement tracer in several wells to ensure connectivity from injector to several producers are efficient and optimal. These methods were performed for several regions of this area which contains a large number of well, nearly 200 wells consist of vertical, deviated and horizontal wells. Reservoir distribution in Windri area interpreted as stacking channel with high sinuosity geometry. This reservoir consists of predominantly of marginal marine claystone interbedded with deltaic sandstones, thin limestone and coal. Bio-stratigraphic analysis from cores shows that the reservoir was deposited in estuarine setting, interrupted by a brief shallow marine incursion. Seismic amplitude mapping at the upper base Gita horizon reveals a system of meandering channels. Compartmentalised reservoir in Windri area divided into 5 sweep pattern to make analysis more detail and accurate. Each of compartment have different characteristic, this is the challenging part in Windri area. East of windri area channel divided into 4 channels and it shows the evolution and movement of the channel that can control the property distribution and reservoir connectivity. Group two shows good result from tracer injection and it is supporting the interpretation of reservoir distribution and characterization within the area. Integrated 4D time lapse seismic generate pressure monitoring movement from each of waterflood phase. The results of this integrated study implementation are excellent, the ineffective water injection pattern now become effective, there is no unavailing injection well, every pattern is connected and link to each other, so that we can achieve our goal to enhanced recovery factor from 16% to 20%. Reservoir characterization using multi-discipline method reduce uncertainty of heteroginity sand and fluid prediction. Integrated waterflood analysis has been implemented for prospect generation, production optimization and overcome pressure degredation in this area.
A collaborative effort between subsurface, operation and commercial team has successfully escalated the value of idle marginal offshore brown field in south east Sumatera, Indonesia. Over the past several years Lidya field was idle due to wellbore and facility problem, big investment value are needed to reactivate Lidya field and it creates hesitation in management decision, also there is a security issue to be considered. This paper describes the methodology applied in evaluating all aspects considered to mitigate the investment risk, escalating economical value and to ensure all parameters perform as expected. The evaluation method divided into three major parts, the first part starts from subsurface study that involving geophysical processing, geologist re-interpretation, and reservoir engineering analysis, one of the most important factors to be taken into account is the necessity of a good understanding of the reservoir in order to increase the possibility of success. The second part is operation evaluation, it captures production engineering analysis from well integrity assessment to artificial lift selection, facilities observation from pipeline assessment to platform refurbishment option and also designing new security system to prevent cable thievery. The third part is the most crucial part to justify the value of Lidya marginal field reactivation project, challenges in this part also interesting, because production sharing contract term has changed from Cost Recovery to Gross Split mechanism, several cases was observed by commercial team to find the very best case with the least risk that might occur and affect the investment. As a result, the value of Lidya idle marginal field was escalated. It can be quantifed from oil rate that increase from 150 BOPD for the last five years before it went idle to 700 BOPD for full cycle project. Economic side also appealing, observation multiple cases led to optimum case that can give total contractor net cash flow at almost 19Million USD in new fiscal term Gross Split mechanism, this number is 4 times higher than Cost Recovery mechanism for contractor profitability. Developing marginal offshore mature asset is a risky business, especially considering high volatility in oil prices. Collaboration and technology are vital to escalating the value and achieving higher recovery factors. Application of the multidisciplinary methods was considered as an appropriate way to approach and manage a complex marginal mature field redevelopment.
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