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Australia is an inexperienced player in field abandonments with early efforts proving complex, high cost, and with last minute approvals due to regulatory and social concerns. Whilst many companies are on top of the costs, they are often isolated from the latest innovations or focused on the next 2-3 years operations. Looking forward, abandonment expenditure will accelerate and be sustained with most companies active and more coming (e.g. Bass Strait, Rankin etc.). Between 2016 and 2030, the overall impact of decommissioning is estimated at $5 billion to $7 billion with the government exposed to up to 60% of this cost through taxes or higher if left with the liability. Considering uncertainty in the regulations, the industry, NOPSEMA and the Government need to deal with what can be left on the sea floor, NORM-related disposals, handling onshore and transfer of liability. Their duty is to protect the environment, provide the platform for safe operations, maximise value for stakeholders but also avoid the taxpayer bearing increased costs/rebates from inefficient programmes. On the cost side, many companies are looking to upgrade abandonment capabilities, and take advantage of new technologies and approaches. However, capabilities and experience are short and regulations unclear. Even so, not all will be equal in their diligence and provisions and hence we are likely to see missed opportunities as an industry. Looking at case studies in Gulf Coast, North Sea and Australia tells us there are many lessons learnt and successes that we should be employing from both environmental and cost angles – e.g. most abandonments struggle with unclear regulations and well/facility deterioration and barrier issues. With these challenges and risks, leadership from all stakeholders should come together to better define and select innovative concepts for decommissioning that moves to sustainable, acceptable and high-value solutions for all stakeholders in the coming years.
Jingwei, Bao (PetroChina Research Institute of Petroleum Exploration&Development) | Xinmin, Song (PetroChina Research Institute of Petroleum Exploration&Development) | Jigen, Ye (PetroChina Research Institute of Petroleum Exploration&Development) | Xiujuan, Fu (PetroChina Research Institute of Petroleum Exploration&Development) | Li, Li (PetroChina Coalbed Methane Company Limited) | Lixin, Meng (Research Institute of Exploration and Development, Dagang Oilfield Compay) | Hongyun, Zhu (Research Institute of Exploration and Development, Dagang Oilfield Compay) | Tianyu, Liu (PetroChina Research Institute of Petroleum Exploration&Development)
Mid-high-permeability multi-faults reservoirs are characterized by high oil rate of wells, mature production facilities and considerable economic benefits, and they have been becoming one of major development objectives in the period of low oil prices. Mid-high-permeability multi-faults reservoirs in China have huge reserves (23.4 billion barrels) and low average recovery (19%) with great development potential. The major challenges to develop these reservoirs are: main sand bodies with super high water cut, part of the reserves with no well control, high percentage of shut-down wells and faster production decline. So combination of IOR and EOR technology (shortly as "CIET") was proposed to promote economic development and further improve oil recovery.
This paper focuses on mid-high-permeability multi-faults reservoirs of Dagang Oilfield in China. The fundamental way of CIET for mid-high-permeability multi-faults reservoirs was explored based on previous experiences and lessons of water flooding to EOR in other oilfields and geological characteristics of Dagang Oilfield. Well pattern optimization was studied by combining the fuzzy cluster, F statistics and independence test method and mathematical model of well location optimization, and basic practice of CIET well pattern rebuilding was given. The effect of CIET pilot was evaluated based on dynamic analysis and field practice, then suggestions of improving CIET were put forward. The development potential of CIET in Dagang Oilfield was evaluated base on the results of field pilot.
The fundamental way of CIET was explored as follow: when oil production of water flooding redevelopment decreased continuously or implemented for 2 to 3 years after IOR, for main sand bodies, several infilled wells were increased and water injectors or flooded producers were converted to polymer injectors and injection-production pattern was optimized by well pattern rebuilding. For minor sand bodies, layer series and pattern were reorganized to improve control degree of reserves for further water flooding. The key point is that main sand bodies and minor sand bodies are controlled as a whole by injection-production pattern and polymer flooding and water flooding concerts in the different sand bodies. The major strategies for CIET in multi-faults reservoir were proposed and technology process of well pattern optimization and reorganization of CIET was made, and all these technology and strategies were applied in pilot test of CIET in Dagang Oilfield. The oil rate of pilot wells improved from 1204 BOPD to 1420 BOPD and the water cut declined from 91.4% to 88.7% and obvious downward trend in RF-WCUT plot was appeared after two years. There were 29 oilfield blocks with OOIP of 1.0 billion barrels in Dagang Oilfield were suitable for CIET and 4-7 percents of oil recovery were improved according to evaluation.
This study explores a new approach of sustainable and economic development and further improving oil recovery after water flooding redevelopment for mid-high permeability multi-faults reservoirs. In addition, it provides a field example and references case for the development of other similar oilfields.
Given the heterogeneous nature of the carbonates, significant difficulties arise when attempting to determine productive intervals using only petrophysical evaluations and borehole image logs. This paper discusses how productive intervals are identified by integrating mobility from formation pressure testers. To determine the role exerted by diagenetic processes (mainly cementation and compaction) on the fluid storage and migration pathways within the slope to deepwater carbonates, permeability structures had to be appraised. Over the past several decades, wireline formation testers have proved to be an efficient method of assessing mobility and inferred productivity, in addition to gathering representative fluid samples for accurate pressure, volume, and temperature (PVT) analysis. Recent advancements have further improved the efficiency of wireline testers in such environments by combining the benefits of straddle packer systems with enhanced probes. In this paper, in-depth analysis is presented on the integration of a comprehensive pressure and productivity data set acquired using the latest-generation wireline tools with advanced formation evaluation and image logs. The revolutionary advances provided by a new multifrequency dielectric tool were also used to provide an Archie mn exponent log from continuous in-situ measurement of rock texture.
Uetani, Takaaki (INPEX Corporation) | Furuichi, Naoto (INPEX Corporation) | Yorozu, Hirokazu (INPEX Corporation) | Sasaya, Kazuyo (INPEX Corporation) | Shibuya, Takehiro (INPEX Corporation) | Kiminami, Narihito (INPEX Corporation) | Yonebayashi, Hideharu (INPEX Corporation)
An oil well, referred to in this paper as Well B, experienced a serious emulsion problem soon after the introduction of artificial lift using a hydraulic jet pump. This forced the operator to reduce the production rate to meet sales oil specifications. During its natural flow production period, this well experienced relatively emulsion-free operation. Consequently, the operator continued to use the same demulsifier, after the jet pump production began.
This paper presents results of a number of field trials that took place over 1.5-year period to control emulsions and to improve oil production. Initially, the operator raised the separator temperature but this was not effective. Next, the operator injected xylene into the formation. Although this was reasonably successful, the effect was short-term. It became necessary to open the separator dump valve to drain the emulsions, and reduce the basic sediment and water (BS&W). This expensive operation was only undertaken to maintain production. The operator then explored changing the demulsifier dosage rate and changing the location of the demulsifier injection port, but neither measure was effective. Finally, a series of bottle tests were conducted to find a better demulsifier to replace the original chemical, which was no longer effective. Soon after injection of the new demulsifier, the emulsions disappeared, and the operator regained the production rate.
Based on the field observations and the preliminary laboratory investigations, the emulsions that affected Well B over a period of 1.5 years were most likely caused by the introduction of artificial lift augmented by the continued used of the original demulsifier chemical, the increased production rate, and the presence of asphaltene and clay particles. An important lesson learned from this project was that emulsion treatment programs should be reviewed periodically, especially when operating conditions change.
Appraisal adds value to potential developments by changing key development decisions (well count, subsea infrastructure requirements, development sequence, etc.), and this value can be quantified using value of information (VOI). The value of perfect information is readily evaluated but, unfortunately, all real world data is imperfect. Quantifying the value of this imperfect information requires assessment of either (i) the likelihood of the appraisal activity correctly resolving the value of an uncertainty, or (ii) the impact of the activity on the post-appraisal uncertainty range, both of which can be problematic. Traditional value of imperfect information analyses tend to focus on resolving only a single uncertainty and becomes difficult to apply as the number of uncertainties addressed by a single appraisal activity increases.
This paper describes a fit-for-purpose probabilistic approach to enable the rapid evaluation of perfect and imperfect value of information for a range of appraisal alternatives. The workflow is demonstrated through its application to a recent deepwater appraisal well which included an extended well test selected as the preferred activity from amongst a range of alternatives (including conducting no further appraisal).
The workflow uses a Monte Carlo spreadsheet tool to generate gas in place (GIIP) and estimated ultimate recovery (EUR) estimates for individual reservoir elements, which are then aggregated to field level estimates. A large number of individual trial values are captured and interrogated in conjunction with a set of heuristics to allow the rapid generation of probabilistic development plans (without needing to rely on a small set of deterministic realisations). Distributions and dependencies defined in the spreadsheet can be readily altered, enabling robust evaluation of the impact on EUR and preferred development plan for each appraisal alternative and outcome (low/mid/high). The EUR and development plan are then used in an economic model to quantify the value added by each appraisal activity. The highest value appraisal activity, in this case the appraisal well with an extended well test, was executed and a post-appraisal lookback was completed to review the value of information analysis once the appraisal results were available.
Daqing Oilfield is a heterogeneous sandstone oilfield with multiple layers. In order to protect the environment, produced water is widely recycled to prepare polymer solution, leading to great polymer consumption and poor economic effectiveness. For this reason, an exploratory research on anti-salt polymers is carried out. Polymer LH2500 is screened out and applied in pilot test in No.3 Block of Xingbei development zone, Enhanced recovery factor reached 10.3%, 45% polymer consumption was saved for ordinary polymers.
However, as produced water is recycled to prepare polymer solution, anti-salt polymer pilot test is urgently needed. To further enhance the recovery factor, anti-salt polymers of low concentration should have high viscosity in the high underground salinity.
Buenrostro, Adrian (Saudi Aramco) | Arevalo, Alfredo (Saudi Aramco) | Alzaid, Mustafa (Saudi Aramco) | Abulhamayel, Nahr (Saudi Aramco) | Driweesh, Saad (Saudi Aramco) | Chacon, Alejandro (Halliburton) | Fadul, Jose Camilo Jimenez (Halliburton) | Noguera, Jose (Halliburton)
Drilling technologies are constantly being developed as operators push the envelope limits to maximize reservoir contact and increase hydrocarbon recovery. These advancements in well construction challenge the well intervention community to seek innovative solutions to successfully intervene in these wells. This paper discusses the successful combination of a slim OD measurement-while-drilling (MWD) tool run on coiled tubing (CT) for real-time survey of the open hole lateral wellbore, followed by a stimulation treatment at appropriate depths for all laterals in a single CT run.
Saudi Arabia has been in the forefront of maximum reservoir contact well construction with the drilling of multilateral open hole gas wells; thus, the need for CT operations to enhance current offerings and procedures. For this application, several tests were performed to determine the feasibility of the combination of necessary tools to be able to steer, identify, and pump the stimulation treatment in a single run. MWD tools were run on CT in this multilateral gas well, and the stimulation treatment was performed during the same CT run.
The common practice in the study area was to run in hole down to total depth (TD) and determine, only by depth difference, in which lateral the CT was located. The uncertainty level increased exponentially when TDs of the laterals were within hundreds of feet because the treatment could potentially be performed in an alternate lateral, rather than the one intended (
The MWD tool run on coiled tubing (CT), implemented a procedure explained in this paper to eliminate the uncertainty associated with previous technologies used for in real-time CT positioning inside the wellbore. The CT position is now reliable verified by survey match with real time readings from CT tip, allowing the certification of job placement in the desired wellbore path, to complete the intervention associated to the CT intervention; i.e.,: "a stimulation treatment" to be done specifically and independently for all laterals in a single run on each. This project open the doors for many other MWD-guided CT interventions to be applied in such conditions.
Transport of solid particles in oil and gas pipelines is a common occurrence in the oil-gas industry. Solid particle transport occurs at various phases of an oil-gas development project: transport of drill cuttings during exploration and completion, and transport of sand particle during production. Current research and development in this space focusses on the physical and numerical modelling of the phenomenon. The concentration of sand within a pipeline will determine the type of modelling required. The literature provides a suite of empirical models to study flows with sand concentration greater than 1% by volume, especially during wet drilling operations. Although suspended sand concentration in production pipelines is nominally much less than 1% when adequate sand control is deployed downhole, there are flow velocities below which result in sand deposition, accumulation and blockage in a pipeline. There are presently limited models to simulate sand transport and deposition in the dilute sand concentration regime as it applies to the production phase. This paper will present some preliminary results using Discrete Particle Modelling to predict the transport and deposition characteristics of low concentration solid particles flowing in a liquid medium. Simulations are also supplemented by physical experiments conducted in a 2″ pipeline systems with water as the carrier fluid.
Yixiang, Zhu (Research Institute of Petroleum Exploration and Development) | Xinmin, Song (Research Institute of Petroleum Exploration and Development) | Benbiao, Song (Research Institute of Petroleum Exploration and Development) | Changbin, Tian (Research Institute of Petroleum Exploration and Development) | Shunmin, Ma (China National Oil and Gas Exploration and Development Corporation) | Yan, Gao (Research Institute of Petroleum Exploration and Development) | Yong, Li (Research Institute of Petroleum Exploration and Development) | Weimin, Zhang (Research Institute of Petroleum Exploration and Development) | Zhuo, Liu (Research Institute of Petroleum Exploration and Development) | Xiaowu, Zhen (China National Oil and Gas Exploration and Development Corporation) | Baozhu, Li (Research Institute of Petroleum Exploration and Development) | Shuhong, Wu (Research Institute of Petroleum Exploration and Development) | Chengji, Wei (Research Institute of Petroleum Exploration and Development) | Bo, Liu (Peking University) | Qiulin, Yang (Research Institute of Petroleum Exploration and Development)
The Upper Cretaceous Mishrif Formation is widely distributed in the Middle East, and it is one of main reservoirs in the super-giant Rm Oilfield. However, since development in 1954, its Mishrif carbonates, accounted for 45% oil-reserves, are not largely developed with only 5.5% oil-recovery due to complicated reservoir architectures and elusive thief zones, the abnormal high-permeable strips that can cause water-injection breakthrough. Therefore, it is critical for the successful development of the Mishrif to make certain the different reservoir architectures and thief-zone distributions.
Based on the investigation of lithofacies sensibility and cluster analysis of logs, petrophysical interpretation models of lithofacies associations have been acquired calibrated by core facies. After studying rock characteristics, genesis and petrophysical-logging responses on high permeable layers, 2 kinds of petrophysical models have been extracted for thief-zone identification. In the framework of isochronal stratigraphy, the relationships between the depositional cycles, palaeogeomorphology, sedimentary differentiation, lithofacies associations, and thief-zone distributions were studied, and the reservoir architecture models of the Mishrif carbonates have been revealed in a typical section. Finally, the spacial distributions of coarse lithofacies associations and thief zones in the critical period were predicted integrating petrophysical interpretations and geology genesis.
Results reveal that, the Mishrif Formation, generally associated with two upward-shallowing sequences, MA and MB, can be further divided into 6 intervals, from the bottom up: Z1, Z2, Z3, Z4 of MB, and Z5, Z6 of MA. 9 lithofacies associations in depositional units can be determined by petrophysical interpretations, and the Mishrif reservoirs have varied structures of lithofacies associations in different periods: Z1 has upward-shallowing structures as from distal-mid ramp, DMR, bioclast-shoal complex, BShC, to rudist-reef-shoal complex, RRfShC, vertically, and has progradation laterally; Z2 and Z3 have distributions of lagoon-back-shoal complex, RRfShC, BShC and DMR; Z4 and Z6 are mostly barriers or buffers; Z5 could have permeable patch rudist/coral biostromes in palaeohighs. Thief zones,formed by marine waves erosion and leaching on tops of reef-flat buildups, being less-than 0.5m single thickness and distributed in clustering areas laterally, are often developed in RRfShC and BShC. Considering different structures of lithofacies associations and thief-zones, and their influences on injectors and producers, the Mishrif reservoirs architectures can be divided into 5 types: Type A, Type B, Type C, Type D and Type E, in which, Type A has thief-zones in whole intervals of injection-production wells, and Type B has parts of thief-zones in either injection or production wells, and they are very important in oilfield development.
The methodology and results in this paper are of great references for the Mishrif and similar carbonates.
Lei, Zhengdong (Research Inst. of Petroleum Exploration and Development) | Liu, Tong (Department of Engineering Mechanics, Tsinghua University) | Xie, Chiyu (Department of Engineering Mechanics, Tsinghua University) | Wang, Moran (Department of Engineering Mechanics, Tsinghua University) | Zhang, Zike
Nowadays, reservoirs with a low or extremely low permeability are of crucial importance for additional oil/gas recovery. Better understandings of multiphase displacement at pore scale in such unconventional reservoirs are necessary. Since the microscale interfacial transport plays a very important role in such processes, researchers were devoted to discover phenomenon at smaller and smaller resolution, and even further to nanoscale. However, this is extremely consuming on both experimental techniques and computation resources. Therefore, we are wondering whether there exists a cut-off resolution or not, below which the absolute and relative permeability are changeless.
In this study, the Navier-Stokes equation for fluid flow is directly solved through porous media. For two-phase flow, the volume-of-fluid method is applied. The numerical code is written within the framework of OpenFOAM, which is a widely used open source CFD solver recently.
The method is validated through several testing cases, which indicates the accuracy of capturing the interface action, wetting phenomenon, and permeability. After validations, we perform a series of modeling of single-phase and two-phase flow simulations in low permeability reservoirs, with special focus on the scale effect. The rock samples are taken from the low-permeability Changqing oil field in China. We reproduce the digital rock structures at various scales by using the micro-CT scanned data. The results indicate that the scanning scale has great impact on the predicted permeability, and the reservoir permeability increases with resolution due to the increasing of micro pore connectivity. However, this tendency is found to decline when reaching a higher resolution.