Maior, Caio B. S.Macedo, July B.Lins, Isis D.Moura, Marcio C....
10页
查看更多>>摘要：Reliability estimation is an essential task to ensure predictability on the life of equipment installed in oil wells, allowing forecasting costs, planning maintenance, and estimating system availability. However, data may be rather scarce and/or expensive to obtain, especially for technologies under development in the Oil and Gas (O&G) industry. The information is frequently available in generic databases and expert opinions. In the Bayesian framework, the prior knowledge about a system's reliability is updated as a new field and/or test data are gathered. This paper proposes an approach that does not require direct elicitation of parameters to define informative prior distributions for the reliability function using fault tree analysis, expert's opinions, and/or generic data at the system level of equipment under development. Specifically, the method-of-moments and maximum-entropy are adopted to propagate downward the uncertainty from the system level through the failure modes until the basic events of the fault tree, weighted by the expert knowledge of the failure behavior. Then, in possession of all prior distributions of the basic events, the information may be propagated upward based on Monte Carlo simulation to update the system reliability distribution. Finally, we present a case study of the proposed methodology applied to a novel open-hole expandable packer, a completion equipment recently installed in a Brazilian oil field. The failure modes and failure causes are discussed, and, after expert elicitation, the definition of the informative prior distribution is achieved. Therefore, we estimate the reliability for a given time and assess if the novel equipment attains the company's risk target, taking O&G standards as reference.
查看更多>>摘要：Directional drilling decision making is complicated by the presence of multiple objectives and constraints. Existing directional drilling advisory methods find a balanced solution through optimization over a weighted sum of the objectives, but the weights are often chosen arbitrarily or based on rough estimates. In addition, existing methods only return a single solution to a multi-objective problem that likely does not have a single, best solution. The work presented here overcomes these limitations by identifying a set of feasible, diversely performing (i.e., Pareto optimal) solutions for the directional driller to choose from. In this novel approach to directional drilling steering optimization, the directional drilling steering problem is framed as a constrained optimal control problem over a finite horizon. A wellbore propagation model that is calibrated at set interval using field data was used to estimate system responses for a bent-sub mud motor drilling assembly. Pareto front approximation was used to solve the problem and a multi-objective evolutionary search method was leveraged to solve this optimization problem and present the directional driller with a set of Pareto optimal solutions that satisfy the problem constraints. The proposed Pareto front approximation approach was validated against a set of field test cases. These demonstrate that the proposed method is capable of finding feasible, high-performing solutions to these real-world problems sufficiently fast to be of use for real-time directional drilling advisory in the field.
查看更多>>摘要：ABS T R A C T This study presents a theory describing surge and swab pressure when a drillstring is hanging in the slips of a heaving vessel. Downhole pressure measurement shows high pressure pulses in these instances, higher than can be explained with simple steady-state calculation. Several factors and parameters affect this pressure, such as annulus geometry, drillstring elasticity, wellbore friction, fluid compressibility, advanced fluid rheology, and fluid inertia. The advanced fluid rheology includes a flow-development phase and a simple fluid thixotropy model. The theoretical model is tested and compared with actual field data recorded at the surface and downhole, both pressure and string acceleration are measured. Key findings from this study are: (1) The annular flow is induced by the axial stick-slip motion of the bottomhole assembly; (2) The surge swab pressure consists of a pressure-loss term and an inertia term, where the latter is the dominating one in this case; (3) The short periods of the axial string motion call for a transient analysis to get an accurate estimate of the pressure amplitude.
Cartagena-Perez, D. F.Alzate-Espinosa, G. A.Arbelaez-Londono, A.
9页
查看更多>>摘要：This paper focuses on understanding the conceptual evolution and practice of sand management through six stages. The geomechanical mechanisms leading to sand production are presented at different scales for comprehensive conceptualization. The concept of "conservatism" is assumed when analyzing passive and active methods for sand control and in the models and approaches to the sanding risk. There is a strong relationship between oil prices and publications (papers) about sand management and sand control. At its core, sand management considers sand production not as a problem but as a phenomenon that demands an intensive study of the genesis and mechanism of sanding. However, the risk assessment must be considered instead of avoiding sand influx as sand control currently does. This paper illustrates how the focus of technical literature and practices has adjusted its questions about sand management through different stages of understanding. Therefore, this paper helps the technical community understand sand management from its historical conceptualization and its relationship with multiple external factors.
Carvalho dos Santos, Juliana MaiaRosa, Daiane RossiSchiozer, Denis JoseDavolio, Alessandra...
14页
查看更多>>摘要：In the last ten years, 4D seismic (4DS) data acquisition is evolving to permanent reservoir monitoring (PRM) systems where sensors are installed at the ocean-bottom, collecting seismic data according to the project's monitoring demand. Simultaneously, reservoir management workflows evolved to include uncertainties, where multiple reservoir models may be considered. Model-based approaches for developing and managing a field rely on error minimizations between modelled and measured data, traditionally from well production data, and eventually adapted to 4DS data. This study presents a fast, robust and unsupervised workflow to provide a comprehensive diagnosis of multiple reservoir simulation models using similarity indicators with observed 4DS. The methodology comprises a seismic forward modelling to convert hundreds of models from the reservoir engineering domain to the seismic domain. The diagnosis includes a novel region-by-region approach to compare the predicted synthetic seismic response with the observed 4DS anomalies using ternary maps generated from Gaussian mixture models (GMM), in addition to a magnitude metric. The methodology is tested in an ultra-deep turbidite field from the Campos basin in Brazil with a PRM system that captured various 4DS anomalies of different polarity, magnitude, shapes and sizes over several production and injection years. The contributions of this work are demonstrated in four applications: (1) feedback on various iterations of geomodelling, (2) feedback on well and seismic data assimilation, (3) quick evaluation of a new seismic monitor, and (4) ranking models for further decision-making studies. The workflow advantages are proved along the model-based reservoir management outline. For application (1), we successfully flagged which 4DS anomalies were being honored in the simulation models and quantified the impact of introducing features interpreted from seismic monitors in the geomodelling. For application (2), we quantified simulation model improvements provided by data assimilation. For application (3), we rapidly evaluated the quality of the seismic monitor against the existing simulation models as soon as the new seismic acquisition and processing was complete, validating the requirement to re-visit the simulation models. Finally, the workflow was crucial to select best models, out of hundreds, for the decisionmaking process, in application (4).
查看更多>>摘要：Dynamic data from oil and gas reservoirs (such as well-production or 4D seismic data) have been used often to reduce uncertainty in reservoir simulation models. These data are assimilated in the simulation models separately or jointly. Assimilation of 4D seismic data conventionally involves with a petro-elastic model (PEM) to transform outputs from the simulation models to elastic properties. The PEM is a set of different equations with uncertain parameters and its inclusion in assimilation algorithms calls on multidisciplinary teams of geoscientists and engineers. Moreover, PEM requires extraction of different outputs from the simulation models for the seismic forward model calculations. The extraction process can be costly for large-scale simulation models of giant reservoirs. This research presents a new petro-elastic proxy model (named DAI-Proxy) with a novel formulation to substitute the PEM and integrate 4D seismic data. DAI-Proxy relates time-lapse acoustic impedance to a summation of saturation and pressure changes with two coefficients which are functions of porosity. As the proxy is an approximation of the PEM, its application is affected by model error. We introduce two approaches to account for the proxy model error: (1) considering uncertain coefficients for the DAI-Proxy and (2) using fixed coefficients in the proxy while estimating model errors statistics from the prior ensemble of models. We incorporate these two approaches with a data assimilation algorithm to assimilate simultaneously 4D seismic and well-production data. A benchmark case is used with different cases of data assimilation to compare the DAIProxy and the PEM applications. Results show that data match quality for 4D seismic and well-production have similar responses for the PEM and DAI-Proxy implementations. In terms of production forecast, using fixed coefficients in the proxy with its model error treatment create a data assimilation framework comparable to the PEM case. Our results indicate that the traditional PEM application to integrate jointly 4D seismic and wellproduction data can be replaced with our new DAI-Proxy application. Given the degree of uncertainty in the PEM, related to the rock and fluid models, our proxy provides similar results with fewer uncertain inputs. The proxy offers further advantage as it needs less outputs from the simulation models for seismic forward model calculations. In addition, it helps petroleum engineers to use a computationally less expensive model (light model) as a substitute for the PEM to assimilate 4D seismic data.
查看更多>>摘要：As a challenging engineering problem, the lost circulation in fractured formations seriously hinders the efficient development of oil and gas wells. Clarifying the weak layer is the key to improve lost circulation prevention and remediation. Nevertheless, due to the complexity, randomness, and interference of engineering factors, a mature lost circulation prediction method of fractured formation has not yet been formed. This work, based on geomechanical modeling, combining with logging and seismic data, constructs the three-dimensional fracture intensity spatial distribution, the three-dimensional minimum in-situ stress spatial distribution, and the threedimensional brittleness index spatial distribution of the target oilfield, respectively. At the same time, the analytic hierarchy process is used to establish a three-dimensional lost circulation risk index of the target oil field, and a classification evaluation standard for lost circulation risk is proposed. This method is applied in the Bohai A oilfield, the three-dimensional lost circulation risk index of the entire oilfield are established. Three hundred seventy-seven lost circulation sample points of drilled wells are selected, and a classification evaluation standard for lost circulation risk is established for the Bohai A oilfield. The research results show that the classification evaluation standard for lost circulation risk has good guiding significance for subsequent drilling in this area. It can scientifically guide the design of well trajectory and well structure of subsequent wells, and improve lost circulation prevention.
查看更多>>摘要：Steam-based huff-and-puff technology has gained a great deal of attention in heavy oil thermal recovery, which however suffered water invasion and steam channeling. In addition, the high-temperature and -salinity seriously restrict the implementation of conventional blocking agents. Here, an innovative composite foamed gel formula consisting of a novel toughening agent is developed to adapt such harsh conditions (175 degrees C, 20 x 104 mg/L). Specifically, orthogonal testing is carried out for formula evaluation and optimization, during which the influences of component concentration, temperature, pH and salinity on the gelling time and gel strength are determined experimentally. The formation and toughening mechanism are illustrated by infrared spectroscopy and scanning electron microscopy (SEM). Blocking performances of ordinary foam, gel and novel foamed gel are compared through sandpack floodings. It is shown that the optimal formula is composed of 4.3 wt% alkali lignin, 0.35 wt% toughening agent, 4 wt% phenolic resin and 0.5 wt% foaming agent. The gel strength reaches G level at 160 degrees C after 3.5 h. The gel is still stable at 175 degrees C under a dehydration rate of 10% after one month. Even under 20 x 104 mg/L salinity, the gel strength still reaches the G level after 22 h. Much higher resistance factor of the alkali lignin foamed gel have been achieved over ordinary foam and gel. The innovative foamed gel here could adapt the harsh conditions perfectly to mitigate the adverse impacts of water invasion and steam channeling, which in turn improves the steam-based puff-and-huff efficiency significantly.
查看更多>>摘要：This case study highlights that shale wells drilled with tight well spacing in the same landing zone using the same fracture treatment plan, commonly show large variance in well productivity. Searching for the root cause(s) of this variance in performance, we conclude that the factory model - which assumes wells can be engineered in reproducible and identical ways - is not yet feasible in practice. For each well, largely similar fracture treatment schedules result in different fracture half lengths. Also, a significant proportion of perforations may fail to create any hydraulic fractures at all. This new reality means that underperforming wells in otherwise promising acreage are more likely an indication of varying fracture treatment response, rather than a result of poor source rock. Research focusing on the reduction of fracture treatment variance therefore deserves priority and may help steady the performance of future wells.
查看更多>>摘要：The rheological properties of poly(ethylene glycol)(PEG)/Laponite (R) RD (Lap) and poly(pmpylene glycol)(PPG)/ Lap aqueous dispersions, with 2% polymer and different clay concentrations, were investigated at 25 degrees C in order to establish the optimal composition to formulate a system applicable as drilling fluid. Some of the most important parameters, such as low shear rate viscosity, plastic viscosity, yield stress and flow behavior index, were determined and discussed. The PEG/Lap and PPG/Lap dispersions containing more than 2.55% and 3.10% clay, respectively, could be considered in the formulation of drilling fluids. The yield point value of dispersions, which is suitable for drilling fluid applications, increased while their plastic viscosity decreased in the presence of NaCl. By addition of NaCl, the complex viscosity of these samples becomes independent of temperature in the range 10 degrees C - 65 degrees C. Zeta potential value decreases as the Lap concentration increases up to about 3% clay and, higher clay content no longer affects it.
NSTL
Elsevier