Reservoir Management Activities Research Articles

Plankton and macro-benthic invertebrate diversity of Apodu Reservoir in Malete, Nigeria

The present study investigated the physicochemical, phyto- and zoo-plankton, macro-invertebrate composition and abundance in Apodu Reservoir in Malete, Ilorin, Kwara state, Nigeria. Samples were collected twice a month in duplicate using standard techniques between February and July 2021. The physicochemical parameters of water: pH, electrical conductivity, water temperature and total dissolved solids were measured in situ using a portable water tester, and the other parameter were measured using standard methods. A sampling net with a mesh size of 0.5 mm were used for plankton collection while benthos were sampled using an Ekma grab sampler. The species richness and diversity were calculated using PAST 4.03 software. The result of the physicochemical parameters, phyto- and zoo-plankton and benthic macro-invertebrates showed significant differences between dry and rainy seasons. Nineteen species of phytoplankton and 13 species of zooplankton were identified in the reservoir. The Simpson index (1-D) values for dry and rainy seasons were 0.7654 and 0.8595, respectively, while the Margalef index values for dry and rainy seasons were 1.82 and 2.919, respectively. The study indicated that the reservoir water was slightly alkaline (pH 7.63 – 8.63) and had a low level of dissolved oxygen (4.9–5.8 mg/l). The occurrence of pollution-resistant phytoplankton species: Oscillatoria spp., Microcytis spp., and Microthamnion zooplankton species: Bosmina meridinalis, Keratella tropica, Branchionus calyciflorus and macro-invertebrates species: Namalycastis abiuma indicated the eutrophic status of the reservoir water indicating the reservoir is under anthropogenic pressure. Therefore, reservoir management activities such as protecting the reservoir areas and proper functioning of the reservoir to reduce, human activities are recommended.

Implementasi Kebijakan Peraturan Gubernur Daerah Istimewa Yogyakarta Nomor 9 Tahun 2009 Tentang Pengelolaan Kawasan Waduk Sermo Kabupaten Kulon Progo

This research was conducted to find out how the implementation of the special regional governor's policy of Yogyakarta Number 9 of 2009 concerning the management of the Waduk Sermo Area. The research was conducted in Kulon Progo Regency with qualitative techniques. Determination of information is done by purposive sampling technique then the data is analyzed by reducing the data, presenting the data and drawing conclusions. The results show that the Waduk Sermo management policy as a whole has been running effectively, but there needs to be an increase in management intensity such as the development of various aspects of resources, organizing socialization and useful activities to support reservoir management activities, and optimizing coordination between the public works and spatial planning (PUPR) Office of Kulon Progo Regency and Serayu Opak River Basin Great Hall (BBWSSO). Supporting Factors There is good coordination between the Waduk Sermo management and the surrounding community, there is awareness and commitment with various parties in the utilization and preservation of the Waduk Sermo, and the availability of supporting facilities for the operational activities of the Waduk Sermo, while the inhibiting factor is that various technical violations are still found in the utilization of the Waduk Sermo, BBWSSO has limited authority in taking direct action against violations that occur, and it is difficult for the surrounding community to obtain permits to open rides or tourist attractions in the reservoir area.

Slip behaviours and evaluation of interpretative model of oil/water two-phase flow in a large-diameter pipe

Mixtures of oil and water are common in oil-producing wells. When the oilfield has a mid-late exploitation status, the production of oil and water gradually decreases and the comprehensive water content sharply increases with time. An accurate evaluation of the volumetric flow rate of each phase in the pipe is of importance for diagnosing production problems, developing an engineering design, and guiding reservoir management activities. In this study, the slip behaviours we investigated based on the high-quality experimental data obtained from a multiphase flow loop with a large-diameter (inner diameter: 5.5 inch) vertical pipe with low flow rates (<30 m3/d). Furthermore, the interpretation accuracies of five interpretative models of vertical oil/water flow ware comprehensively evaluated. The results show that the slip trends to increase with decreasing flow rates. However, it was found that, when the flow rate is less than 7 m3/d, the flow rate minimally affects the slip. Additionally, the variation tendency of the slip velocity as a function of the water holdup is not stable, hence, a reasonable interpretative model should be selected according to the water holdup. The slip velocity gradually increased, and was found to be nearly linear, and the slip model proposed by Hasan and Kabir (1999) demonstrated the best adaptability under the conditions of the tested data and a water holdup of less than 0.9. The slip velocity exponentially increased with increasing water holdup and the modified drift-flux model proposed by Wu et al. (1992) was found to be more appropriate under the condition that the water holdup exceeds 0.9. Overall (i.e. for all of the test data), the Hasan model (1999) yielded better processing results for the vertical oil/water flow system under the condition of low flow rates. The analysis in this study provides better insight into the slip between the oil and water phases in a two-phase flow system with a low flow rate. In addition, the interpretative model with the best predictive capability is highlighted in this paper.

Sustainable management of water potabilization sludge by means of geopolymers production

Alumina-containing water potabilization sludge (WPS) is one of the main wastes produced by reservoir management activities. This kind of residues, deriving from treatment processes for water potabilization, recently attracted great attention as starting raw material in the production of innovative building materials. In this study, the use of WPS as aluminosilicate source for the synthesis of geopolymers has been investigated. In particular, two different potabilization sludge deriving from the water treatment plants of two artificial water reservoirs have been selected. For both of the WPS, mineralogical (XRD analysis), physical-chemical (FTIR analysis), thermal (TGA-DSC analysis), porosimetric (BET analysis) and morphological (SEM analysis) properties have been evaluated. A thermal treatment at 650 °C has been performed on the two raw sludge in order to increase their reactivity. Geopolymeric samples have been produced by the hardening of the calcined WPS in two sodium silicate solutions, differing only by concentration, and using two curing temperatures. Obtained specimens have been widely characterized from chemical, mechanical and microstructural points of view. SEM, FTIR and XRD analyses confirmed that the geopolymeric reaction effectively took place for the samples produced by using the more concentrated solution and the higher curing temperature. In general, the mechanical performances reached by the specimens, suggest the possibility of a promising reuse of WPS as raw materials for the synthesis of geopolymer based building precast components.

An assessment of the Upper Succession and the related secondary reservoirs in the Welton Field, onshore UK

Abstract The Welton oil field has produced nearly 20 MMBO (million barrels of oil) since discovery in 1981. Now in post-plateau decline, there is increasing reliance on a series of secondary reservoirs. Production has been from a suite of stacked reservoirs deposited by large-scale prograding delta-plain systems of early Westphalian age. Whilst the bulk of production has been from the Basal Succession, a considerable upside is considered to exist in the less well-studied Upper Succession that comprises predominantly distributary channel and crevasse splay deposits which have produced in excess of 3 MMBO. These accumulations occur within the Deep Soft Rock, Deep Hard Rock and Tupton reservoirs. This paper focuses on a sedimentological analysis of cored intervals, integrated with petrophysical logs and detailed production data to enable further recommendations to identify areas of undrained pay, along with identifying additional reservoir management activities that could optimize future offtake from the field. These reservoirs consist predominantly of very fine-grained sandstone, with permeability values rarely attaining 100 mD and average porosity values of 10–12%. Recommendations include executing tracer communication tests and building a detailed field model, as well as a pilot water-injection scheme to increase production from some of Welton's secondary reservoirs. Supplementary material: A full set of detailed sedimentological logs for each of the cored wells in this study is available at https://doi.org/10.6084/m9.figshare.c.3593984

Application of Integrated Reservoir Studies and Techniques To Estimate Oil Volumes and Recovery—Tengiz Field, Republic of Kazakhstan

Summary Recent technical studies and probabilistic techniques have been integrated to build reservoir models for Tengiz field. Tengiz is one of the deepest supergiant oil fields in the world and is on the shore of the Caspian Sea within the Republic of Kazakhstan. Knowledge of the uncertainties inherent in oil recovery is a key to proper reservoir management of this important oil field. Probabilistic techniques gave insights into the importance and ranking of key reservoir uncertainties. This ranking is used to reduce reservoir uncertainties and to guide reservoir management activities. A structured Monte Carlo Technique has been used to construct several thousand static models of Tengiz field. Construction of Monte-Carlo models is fast and allows the impact of key uncertainties to be explored. Static reservoir uncertainties investigated include wireline log calibration, structural elevation, geostatistical parameters (such as variogram length), water saturation, and location of the boundary between facies intervals. Investigating the uncertainty in the dynamic performance of the model is computationally intensive. Experimental design techniques were used to minimize the number of computationally expensive simulation runs. Key dynamic variables investigated include: oil in place (OIP), gas/oil relative permeability, permeability enhancements, vertical-to-horizontal permeability ratio, well productivity, the water/oil contact (WOC) depth, and production capacity. The methodology for generating the range of possible outcomes for some development scenarios in Tengiz is discussed here. The application of Monte Carlo and experimental design techniques to identify the high impact static and dynamic parameters is reviewed. The construction of a probabilistic distribution of OIP and recoveries is demonstrated for one development alternative for Tengiz field. This study found that for this development alternative, the OIP, gas/oil relative permeability, and ratio of vertical to horizontal permeability have the greatest impact on the estimated oil recoveries.

Managing Risks Using Integrated Production Models: Process Description

Technology Today Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering. Summary This paper describes an asset-management-analysis process that helps to quantify and manage uncertainty associated with field-development design, implementation, and operation. The risk-based integrated production model (RIPM) process is based on the principles of integration, quantification, and validation to define uncertainty in total-system performance and the associated economic impact of each delineated scenario. This process provides a more robust understanding of the risks and potential value of the prospective enterprise on an ongoing basis. Introduction Complex producing systems are often divided into subsystems (reservoir, well, and surface facilities) that typically are treated independently in both design and operations. Historically, each engineering function models and optimizes its component of the system on the basis of "local" instead of "global," or system, criteria and hands off the results for successive downstream functional analysis. The results from deterministic technical analyses that address specific problems in the different subsystems are then weakly linked (if linked at all) manually by the user (Fig. 1). Sometimes, because of timing constraints or lack of information, a component of the system is skipped or addressed superficially. This "linear" process is cumbersome and slow, limiting both evaluation of alternative options during the design phase of a project and the ability to react to new information during the implementation and operation phases. The system's design and subsequent performance suffer because optimization is managed at the subsystem level only and one subsystem's design may constrain the overall system unnecessarily. Recent advances in integration have enhanced production optimization and asset-management-analysis processes. Analysis with "dynamically" linked tools (i.e., without user interface) increased field productivity by an estimated 15% over base decline in a mature optimized field.1 Integration in reservoir-management analysis also increased reserves recovered, productivity, and cost savings.2 Previous approaches to managing day-to-day operations and production-optimization activities, however, relied on a deterministic approach, which tends to overlook uncertainty in data, model, and/or assumptions. An improved process also is needed to link production-optimization and reservoir-management activities to achieve real-time reservoir management (i.e., to process data generated in a subsystem, analyze its impact on the global system, and enact appropriate changes to the depletion plan, all in a short time). The RIPM analysis process was developed to address the disadvantages associated with the linear approach. RIPM encompasses both the process and the tools that facilitate making optimal and strategic decisions in design, implementation, and operation phases of a project to enhance the value of an asset over its life. Three key principles of integration, quantification, and validation are applied throughout the process. Integration evaluates the impact of an option on the entire system; quantification compares different options on a consistent, absolute basis; and validation identifies gaps in data and deficiencies in technical models to define uncertainty and subsequent avenues for improvement. The tools used to develop the quantitative models vary from application to application, depending on problem complexity, solution detail, and time required for solution. Tools are selected on the basis of their ability to provide quantitative solutions while adhering to the process principles. The approach uses dynamically linked models of the reservoir, well, and surface-facility subsystems [i.e., integrated production model (IPM)] to evaluate system performance quickly (Fig. 2). Risk caused by uncertainty in assumptions, data (e.g., physical parameters, economic data), or model predictions is also quantified when appropriate and integrated with the IPM to give an RIPM. For example, input variables may have a range of possible values rather than a single point, resulting in a probable distribution of outcomes. The result is an iterative process to evaluate alternative options for design quickly and to react to new data during implementation or operation phases of a project over the life of an asset. The following sections describe the process and the available analytical tools. Ref. 3 will describe example applications. Process Description The process consists of six fundamental building blocks:identify alternative options/scenarios,collect data,construct models,analyze performance on subsystem and system levels,analyze options with associated uncertainty, anddecide on a strategic path. Because of the iterative nature of the process, the sequencing of the building blocks can differ, depending on the problem. In one application, the process might start with the identification of options, in another, with analysis of data uncertainty. In either case, the process is customized to the problem so that the solution is not restricted.

Managing Data Assets To Improve Business Performance

SUMMARY A project to improve integration of data and computer applications for exploration, appraisal, and field-development planning is ongoing at Sarawak Shell Bhd. An increased awareness of the importance of data as an asset has resulted in definition of a project aimed at improving the exploitation and management of this asset. This is expected to affect business through increased staff productivity and realization of new development opportunities through better subsurface interpretation and field management. INTRODUCTION During 1995-96, Sarawak Shell underwent an organizational review to transform itself into an asset-based organization. Integrated asset teams that encompass exploration, development, and reservoir-management activities were formed. During the review phase, subsurface- and surface-data management were identified as key areas that needed to be addressed and improved. Small teams were subsequently set up to define the scope and terms of reference for these projects. This paper describes the objectives and setup of the Subsurface Data Integration (SSDI) project. PROJECT MANAGEMENT AND LOGISTICS The goal of the SSDI project is to address the following main activities:data integration, project and corporate databases, applications- portfoliomanagement, data ownership, and procedures. Fig. 1 shows the data challenge, a key value driver for the initiative. The data challenge is from an in-house Shell study that suggested that technical professionals spend 60% of their time looking for data. The SSDI project team coordinates and drives the project and helps the business units implement the improvements. A companywide steering group makes key decisions with representatives from these business units and technical service groups. Fig. 2 illustrates the relationships between the project team, the steering group, and the asset teams. The activities carried out as part of the project are facilitated and supported by the project team but owned and driven by the asset teams through the steering group. This ensures that business requirements drive the tasks and priorities for the project team.

Measuring the Quality of a Reservoir Management Program

Good reservoir management is key to successful exploitation of hydrocarbon resources. Sustaining quality reservoir management programs can be a challenge in view of cross-functional, cross-group requirements plus personnel and priority changes. Reservoir management processes have been defined, and a set of questionnaires has been designed to review reservoir management practices comprehensively, to assess its strengths, to identify areas for improvement, and to provide a method to measure improvements over time.

Reservoir Management Practices

Summary This paper describes the reservoir management practices used at fieldsdeveloped and operated by Esso Production Malaysia Inc. (EPMI). The goal of EPMI's reservoir management activities is to maximize profitability andeconomical recovery of oil. Excellence in reservoir management is achieved withclearly defined and endorsed plans for management of each reservoir and acoordinated process to collect, analyze, validate, and integrate reservoirdescription and performance data into optimal development and depletion plans. Use of a multidisciplinary team to identify problems and to implement timely, innovative solutions is a key problems and to implement timely, innovativesolutions is a key ingredient. Through regular reports to management andfrequent discussions among functional groups, reservoir management objectivesand stewardship performance are communicated. Introduction Reservoir management is a significant component of EPMI's developmentplanning and production operations. Reservoir management planning, which beginsduring predevelopment phases, is emphasized throughout the productive lives ofthe reservoir and field to maximize profitability and economical oil recovery. As contractor to Petroleum Nasional Bhd. (PETRONAS), the Malaysian national oilcompany, EPMI currently operates 12 oil fields with 66 active reservoirs in the South China Sea. The fields are located within the 1976 production sharingcontract (PSC) areas (Fig. 1) about 130 to 260 km [80 to 160 miles] offshore Peninsular Malaysia. Production was initiated in 1978. By the end Peninsular Malaysia. Production was initiated in 1978. By the end of 1991, 28 platformshad been installed and developed with 755 completions. Five additionalplatforms are planned to complete development of the Seligi, Guntong, Tabu, and Dulang fields. The reservoirs in all fields except Seligi, Guntong, Tabu, and Dulang are mature, having produced more than 50% of their expected ultimaterecovery. Reservoir Types and Drive Mechanisms The major reservoirs operated by EPMI can be grouped into six types (see Fig. 2). Most major reservoirs have large associated gas caps where producedgas is reinjected for gas-cap expansion to displace oil downdip to productionwells, thereby avoiding oil losses to the gas cap. The major Groups E, J, and Ksandstones of the Bekok, Pulai, Tiong, Kepong, Semangkok, and Seligi fieldshave rim or pancake-type oil columns with large overlying gas caps and moderateto strong aquifer support. The Palas Group I sandstone is similar except thatthe aquifer support is weak because of poor rock quality and continuity in thesurrounding aquifer areas. At Irong Barat, gravity drainage with gas injectionfor pressure maintenance is the predominant drive mechanism because of the highdip angle, low solution GOR, and high permeability. Full voidage replacement bycrestal gas injection is required to avoid gas-cap shrinkage. The lower Group Jsandstone at Tinggi has strong aquifer support and no gas cap, so injection isnot required. The upper Group J sandstone, however, which is in communicationwith the lower group J sandstone, has a gas ca but weak aquifer support. Consequently, gas is reinjected. At the Tapis, Guntong, and Tabu fields, the Group I and J sandstones have weak aquifer support and long oil columns, soboth water and gas are injected to maximize recovery. Reservoir Management Goal and Key Objectives The company's reservoir management program is an ongoing, dynamic process ofcollecting, analyzing, validating, and integrating process of collecting, analyzing, validating, and integrating reservoir description data andperformance data into an optimal reservoir development and depletion plan. Thegoal of reservoir management is to maximize profitability and economicalrecovery of hydrocarbons. To achieve that goal, the following three keyobjectives were established.Mitigation of production decline in existingfields. With the mature fields exhibiting a decline in productive capacity ofmore than 15%/yr, capacity enhancement is a key requirement. Several programsimplemented to mitigate decline are discussed later.Aggressive pursuit ofnew field development. The recent work completed to confirm and implementdevelopment plans for the North Seligi resource potential illustrates theapproach used.Effective exploration and exploitation of new acreage. Withthe current exploration activities in the PM-5 and PM-8 PSC areas, new acreageis being exploited effectively, but these activities are not discussed in thispaper. Reservoir Management Process Reservoir management practices are initiated before development work beginsand continue throughout the life of the reservoir through the process shownschematically in Fig. 3. JPT P. 1296

Integrated Mainframe/PC Approach for Well-Data-Acquisition Selection

Summary This paper discusses Saudi Aramco's integration of the corporate mainframe database management system (DBMS), a commercial statistical analysis package (SAP), and a PC database program to facilitate the selection of dataacquisition candidates and to track the completion of their requirements. Data-acquisition candidate selection includes wells that require flowmeters, pulse-neutron logs (PNL's), PI tests, and bottomhole static PI tests, and bottomhole static pressure (BHSP) surveys for prudent pressure (BHSP) surveys for prudent reservoir management. Data are easily extracted from the DBMS with user-language programming techniques. Then a SAP uses predefined reservoir-management criteria to process the more than 100 logical process the more than 100 logical records extracted per well. Output from the mainframe program is then imported to a PC data base using batch files. Multiple tabular forms allow the engineer to preview the rulesbased selections, to edit the data-acquisition requirements, and to add comments. In urge fields with hundreds of wells, selection of the optimum data-acquisition candidates is extremely important. The PC database application helps novice computer users select and track dataacquisition candidates more systematically and allows users to have direct control of screen presentations. Other routine work, such as presentations. Other routine work, such as well producing priority, business development plans, and workover selection and tracking, has also been included in the PC data base. Introduction The Northern Area Reservoir Management (NARM) Div. of Saudi Aramco is responsible for reservoir-management activities in the company's offshore oil fields. Reservoir engineers specify the data-acquisition requirements necessary in their area of responsibility. Collecting reservoir-management data is expensive; typical costs are $25,000 for flowmeters, $10,000 for production/injection testing, $40,000 for PNL's, and $2,500 for BHSP surveys. For the purposes of this paper, PNL's, flowmeters, production/injection tests, and BHSP surveys are production/injection tests, and BHSP surveys are used to acquire the following types of data. 1. PNL's are used to monitor bottom- and edge-water encroachment throughout a field. Data are used to specify rate restrictions and well producing priority and to evaluate recovery efficiency. 2. Flowmeters are run to ascertain the contribution of each reservoir layer to the total flow rate and to identify the water entry point, plugged perforations, etc. point, plugged perforations, etc. 3. Production/injection tests are run at various intervals over the life of a well to determine the reservoir parameters that best define the reservoir and to identify workover opportunities. 4. BHSP surveys are run quarterly, semiannually, annually, or biennially at field locations that provide good area coverage for monitoring reservoir pressure, evaluating pressure support, and verifying pressure support, and verifying communication between layers. Previously, the selection of data-acquisition candidates required a time consuming well-by-well evaluation of hundreds of wells. The task was often delegated to entrylevel engineers, and well-defined guidelines on how to do the job best were not provided. The task required many trips to the files, many telephone calls to production engineers, and a great deal of wasted time. In 1988, this task was faciliated for one major field by using the DBMS and a commercial SAP. Standardized, simple criteria were applied to each well to determine whether it required a PNL, a flowmeter, etc. For example, if a producing well had not had a PNL for 3 years it would be identified as PNL for 3 years it would be identified as a PNL candidate. Improvements since 1988 include a menu-driven system that allows the DBMS information-extract program and the SAP to be submitted simultaneously. The SAP can also generate graphic files, if requested on the submission panel. Currently, each major field has a more sophisticated rules-based system stored in a macro library that the SAP accesses. Guidelines for lessexperienced engineers are now readily available and the selection is more systematic. Thus, this routine task is now completed much faster and documented better, and the time saved is used to analyze the data collected.