Chen, Jie (University of Science and Technology of China) | Liu, He (Research Institute of Petroleum Exploration & Development) | Wang, Fengshan (Petrochina Daqing Oil Field Limited Company) | Shi, Guocheng (Petrochina Daqing Oil Field Limited Company) | Cao, Gang (Petrochina Daqing Oil Field Limited Company) | Sun, Yanan (Petrochina Daqing Oil Field Limited Company) | Sun, Chunlong (Petrochina Daqing Oil Field Limited Company) | Ge, Weitao (Petrochina Daqing Oil Field Limited Company) | Wu, Hengan (University of Science and Technology of China)
During the operation of Progressive Cavity Pumps (PCPs), the problem of internal slip which defines the pump performance in terms of volumetric efficiency and lifting capacity always occurs. However, due to the complex geometrical structure and coupling interactions between the stator and the oil lifted, it is difficult to solve the internal slip analytically.
In our study, a new finite element model of PCP with fluid-solid interaction is developed to investigate the internal slip. We established the simulation models of fluid and solid respectively, solved the control equations of them in different solvers and exchanged the results through the fluid-solid interface. Partitioned solution algorithm is employed to tackle the problem of two-way fluid-solid interaction.
Two leakage mechanisms, longitudinal slippage and transversal slippage, were found from our numerical simulation results. For specified design parameters, the fluid leakage can be computed with different hydraulic pressure, thus the volumetric efficiency of PCPs can be obtained. Our computed volumetric efficiency is consistent with experimental results of laboratory test, which can verify our model and simulation method. Furthermore, we studied the influence of different material and structure parameters on internal slip of PCP. The developed model could also be used to compare the volumetric efficiency of different PCPs and optimize the design of PCPs. Our work can be of great significance for the optimization design of new specified PCPs.
In Sakhalin Energy the oil and gas production from all the wells is monitored in real-time by data-driven models. These models are based on single-rate well test data, test-by-difference data and/or ‘synthetic' data generated by physical models. The system is technically easy to maintain, fast to simulate and reconcile with the fiscal meters. SEIC has two new facilities with good instrumentation that allowed for a successful deployment of FieldWare Production Universe for real-time production surveillance and allocation. This paper also highlights the key lessons learnt from the roll-out exercise and the key issues and risks involved during the implementation and execution process.
Aziz, Intan Azian Bt A (Petronas) | Mondali, _ (Petronas) | Mohammad, Mahzan B. (Petronas) | Tajuddin, M Taufiq B (Petronas) | Sapidih, M. Firdaus B (Petronas) | Amir, M. Syafeeq B. Ebining (Petronas) | Brahmanto, Edwin (Schlumberger) | Subroto, Bramanta (Schlumberger)
Enhanced Magnetic surveying technique was introduced to Field Q in Malaysia allowing the tight geological target
requirements to be achieved without impacting the operator's drive for drilling efficiency. Managing wellbore uncertainty is a significant challenge in Field Q, West Malaysia, where the Subsurface Team defines tight reservoir targets to accommodate the uncertainties that they have in a long step out well. Accurate well positioning
becomes crucial in this situation to allow the penetration of multiple small targets. Historical approaches would have involved either running gyro surveys (which introduce more risk and time to the drilling process), or having to "over engineer?? the wells (by creating tortuous well paths and drilling on the line to achieve the small drilling targets) due to the uncertainties of standard MWD surveys. Both of these approaches are against the drive to continually improve drilling efficiency while reducing risks. Magnetic surveying has become increasingly accurate and now provides a cost-effective alternative to gyroscopic surveys in real-time drilling applications. New techniques for identifying and compensating for these errors involve a better understanding of the natural variations in the earth's magnetic field, and new methods of mapping local variations improve magnetic modeling. The enhancement involves a multi-station analysis technique that provides compensation for drillstring magnetic interference and further improved when used in conjunction with geomagnetic referencing, which takes account of localized crustal effects in the earth's magnetic field. With a Geomagnetic Referencing System in Field Q, magnetic survey reduced uncertainty by 60% on average compared to a standard MWD error model. The benefits from this real-time drilling surveying process also means drilling is more accurate, with a reduced need for correction runs, or post-drilling changes to the planned well trajectory.
The Impressed Current Cathodic Protection (ICCP) System is a corrosion control method where there is a flow of electrons to a metal structure, thus protecting it. As a ship owner, the EMP Malacca Strait SA used a coating method combined with the ICCP system to control corrosion on the Ladinda FSO. However, nowadays, the Ladinda FSO is known to carry a decreased volume of oil cargo due to declining oil production. This results in a change in the wetted area on the tanker's hull in the design conditions of the ICCP system from early 1983 to the current conditions (2010) that affect the current magnitude of the protection given. This leads to an over-protection that destroys the coating layer.
To avoid over-protection on the hull of the Ladinda FSO, an analysis and redesign of the ICCP system has been conducted. In the redesign of the cathodic protection system on the Ladinda FSO, the NACE Standard RP 0176-2003 "Corrosion Control of Steel Fixed Offshore Structures Associated with Petroleum Production?? was used as a basic reference in the design. The first step was to make the initial ICCP system design and then rebuild the initial ICCP system design for cathodic protection according to recent conditions. Next, the new design was analyzed and the results are the recommendations. The monitoring system was also redesigned to maintain proper control at a range of -1100 mV to -800 mV vs. Ag/AgCl/seawater.
The new design will needs two transformer rectifier units as the power supply, which will give sufficient voltage to drive six titanium anodes coated with mixed metal oxide (MMO). The capacity of each transformer rectifier is 236.25 kV.A with a DC current of 21 A and DC voltage of 9 V. Four potential test boxes featuring Ag/AgCl reference electrodes and the "Protection Current Control Program?? as the control system and monitoring system are added in this new ICCP system design.
Feng, Yang (China University of Petroleum, Beijing) | Zhengfu, Ning (China University of Petroleum, Beijing) | Qing, Wang (China University of Petroleum, Beijing) | Huiqing, Liu (China University of Petroleum, Beijing) | Shidong, Zhang (Xinjiang Oilfield Company, PetroChina) | Hongmei, Liao (Changqing Oilfield Company, PetroChina)
The Lower Cambrian Niutitang Formation is an organic-rich siliceous mudrocks which is widely considered to be a potential shale gas reservoir in Sichuan Basin of southwest China. An integrated study was performed to characterize the reservoir characteristics. A series of tests were conducted on core samples including organic geochemistry, mineralogical, petrophysical and mechanical properties. A deep insight into the characterization of pore structure in shale reservoir was analyzed by field emission scanning electron microscope, gas adsorption and high-pressure mercury injection.
The results show that Niutitang Formation shale reservoir has the potential for gas exploration and production due to organic matter rich, moderate porosity and high brittleness. The Niutitang formation is of great thickness and the total organic carbon content ranges from 0.16% to 9.15% with average of 3.56%. The porosity of shale samples is from 1.26% to 9.85% with average of 5.78%, and the pulse permeability of matrix is from 320 nD to 890 nD. The total content of brittle minerals (quartz, feldspar and carbonate) is over 70%, and the formation is characterized as rigid and brittle for high elastic modulus and low Poisson's ratio. There are five types of pores in shale: organic nanopores, pores of clay minerals, intraparticle pores of matrix minerals, intragranular pores from microfossils, and microfractures, and the chief are organic nanopores and pores of clay minerals. Nanopores with pore diameter less than 50nm provide the main pore surface area and pore volume, which indicates they are the main place for hydrocarbon adsorption and storage. These results will provide a basis for further evaluation of the hydrocarbon potential of the Lower Cambrian Niutitang Formation shale in the Sichuan Basin.
Maintaining stable operations with high recovery requires routine checking of individual Well Health (WH). A well performing as expected is healthy. It is essential for efficient field operation to detect WH issues early that may reduce overall recovery. An early predictive and WH meta-monitoring tool is highly desirable. Our new approach is designed to provide early identification of existing or developing WH issues - precursors to WH problems if not addressed. ARTAM-WH utilizes in-situ monitoring systems coupled with static data, conducts preliminary analysis and proper cross checking and then notifies engineers/operators. Differentiating this approach is that it is not looking at small data sets but a large palate including both static (the well construct) and dynamic, current performance versus performance expectations. ARTAM-WH provides supporting evidence of WH Issue to the appropriate stakeholder. Notification includes the necessary and sufficient evidence derived from approximate reasoning algorithms combining multiple variables to identify possible issues and testing the WH hypotheses. ARTAM-WH aims to provide early warning signals, including substantiating evidence, to engineers/operators managing large volumes of data generated within monitoring systems; lowering operating costs and expediting the decision-making processes. Reducing time to action; improving operational effectiveness; increasing production due to reductions in unexpected downtime and previous lost profit opportunities being captured. This new approach frees up engineers/operators time to focus on higher priority activities such as developing solutions. Early identification of emerging problems also allows for the ability to handle those problems through normal planning rather than emergency fixes.
Limin , Zhao (Research Institute of Petroleum Exploration and Development, PetroChina) | Longxin, Mu (RIPED, Petrochina) | Haiying, Han (RIPED, Petrochina) | Guoliang, Zhao (RIPED, Petrochina) | Rui, Guo (RIPED, Petrochina) | Jun, Wang (RIPED, Petrochina)
Reservoir characterization is the most important in building robust geological and simulation models. The improvement in reservoir characterization enhances the understanding of the reservoir heterogeneity and reduces the uncertainties on field development. This can be achieved with better descriptions of reservoir frameworks and properties. D oilfield is located in northwest of Oman and it has been rejuvenated by water injection since 2001 using horizontal well line driving pattern. In this paper, comprehensive reservoir characterizations of thin Early Cretaceous Upper Shuaiba limestone reservoir of this oilfield were carried out based on the current data for guiding the further adjustment plan and achieving better development results.
Horizontal well correlation modes were defined based on the reservoir boundary encountered by the horizontal trajectory to construct the reservoir framework. The interpretation and identification of small faults and fractures were identified based on seismic data, FMI logging, core data and production data. Under the guidance of depositional model, data from horizontal wells has been fully used in combination of pseudo-wells to build the 3D geological model to accurately delineate small faults, reservoir boundaries and property distributions. Based on fracture parameters derived from static and dynamic data, fracture network model and equivalent permeability model have been built constrained by fracture density. The intelligent reservoir characterization provides a reliable geological guidance to ensure the reasonable placements of infill horizontal well trajectories through the reservoir. The real horizontal drilling indicates that the oil reservoir accounts for 90% of the total horizontal section for D oilfield.
Under the conditions of injecting pure CO2, the corrosion rate of strings in CO2 injection wells is very low, while in WAG process, because CO2 is mixed with water, corrosion rate of downhole strings is high. Hence, we need to take some anticorrosion measures. Because of the fluctuations in pressure and the changes in temperature due to frequent changes of gas injection and water injection, both of these two processes will cause load changes of the tubing, as well as reduce the tubing seal behavior. WAG technology should be optimized.
According to affecting factors of corrosion of WAG process in CO2 flooding, studies of corrosion prevention measures of wellhead equipment, downhole strings and casing are carried out. Based on different conditions of string mechanics in the WAG process, considering different working conditions, the CO2 WAG process is optimized to reduce fatigue failure due to the fluctuations of pressure and temperature on the strings.
The safety control technology of CO2 WAG is widely used in CO2 flooding test in Daqingzi oilfield. In the CO2 WAG process, the technology optimizes injection strategy and corrosion prevention measures in CO2 WAG injection process, protects wellhead equipment and downhole strings of the CO2 injection effectively, as well as ensures safe and smooth operation of CO2 injecting wells.
Keywords: CO2 flooding, WAG, Anticorrosion, String mechanics, Safety control
In low permeability oilfield, normally fracturing is applied for production and the water injecting pressure is quite high. As most of the major oil reservoirs are flooded by water after fractured, the production rate is very low. With the oilfields further developed, the number of high water cut wells increased. How to further tap the remaining oil and enhance the oil recovery is becoming a big challenge to us currently. In Daqing low permeability oilfield, a pilot test of pressure plugging, water control and oil recovery of high water cut wells was conducted and achieved a good result. The test was including: 1) Further verified the understanding of well and reservoir selection and established the selection standard of the pressure block, water control and oil recovery technique for fractured reservoirs in low permeability oilfield. 2) Optimized field operation process of pressure block, water control and oil recovery. Compensator + K341-114 packer + fixed pressure valve + K341-114packer + ball seat was designed as the plugging string. Small diameter string was studied to repair casing damaged wells. 3) Optimized the chemical plugging agent and developed the fracturing technique of plugging the water cracks through compound water plugging. Production enhancement and water drop were observed through large scale field application.
Li, Qiaoyun (Research Institute of Petroleum Exploration and Development) | Wu, Shuhong (Research Inst. Petr. Expl/Dev) | Wang, Baohua (Research Institute of Petroleum Exploration and Development) | Li, Xiaobo (Research Institute of Petroleum Exploration and Development) | Li, Hua (Research Institute of Petroleum Exploration and Development) | Zhang, Jiqun (Research Institute of Petroleum Exploration and Development) | Meng, Lixin (Research Institute of Dagang Oilfield, PetroChina)
Reservoir numerical simulation, which interests a large amount of reservoir engineers, is an important tool in oilfield development researches. This paper introduces a new generation simulator, which can be used to simulate the traditional and pseudo-compositional reservoirs. This simulator adopts finite volume method, completely implicit time discretization technology (CITDT) and dynamic space discretization technology (DSDT). The multilevel preconditioner solver, which is applied in the simulator, can enhance the computation speed. In this paper, a mature heterogeneous water-flooding oilfield with 30a's development history is simulated by this simulator. In the course of development, there are 242 producers and injectors drilled, and the exploitation strata-series are adjusted frequently. Currently the reservoir has entered the "double high?? stage, more than 79% of recoverable reserves have been produced and the water-cut reaches to 90%. After history-matching and production prediction by this simulator, the results shows that this reservoir numerical simulator can be used to simulate the complex reservoirs with long development history and mounts of wells, and it can describe the production performance precisely. Moreover, the case study indicated that the new generation simulator is a fast and adaptable tool to simulate the complex reservoirs with large scale, which shows its high potentiality in industrial application.