Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Malagon Nieto, Camilo
Abstract Geophysical Reservoir Monitoring GRM systems such 4D seismic are increasingly used in the oil and gas industry because they provide unique and useful information on fluid movement within the reservoir. This information is relevant for many reservoir management decisions; including new well placement, well intervention, and reservoir model updating. Unfortunately, it has been difficult to estimate the value creation of any data acquisition scheme due to the fact that a multidisciplinary approach is required to model the value that future measurements will imply in future decisions. This assessment requires a common decision making simulation frame work that can integrate the input from geo-modelers, geophysicist and reservoir engineers. This work presents an example of how a Close Loop Reservoir Management (CLRM) simplification can be used as a framework for simulating NPV changes due to assimilation of production and saturations in a simple toy model. It combines state-of-the-art data assimilation and uncertainty modeling methods with a robust optimization genetic algorithm to calculate NPV improvements due to model update and its relationship with the NPV obtained from the synthetic reservoir. In this context a simple synthetic model is presented. It recreates a segment of green field under a strong aquifer influence with two discovery wells. The reservoir development requires the selection of 4 well locations at fixed drilling times. The development strategy selection is obtained with the use of a genetic algorithm within the CLRM framework. Subsequently two cases are presented: one of assimilating only production after the first two wells have been drilled, just before deciding the locations of the last two wells; and a second case, in which production and saturation are assimilated at the same time. The saturation map assimilated is assumed to be output of a 4D seismic acquisition. The model update imposes the need of optimally relocate the last two wells which results in a NPV change. The results show how the obtained NPVs is incremented by the relocation of the last two wells in both cases. A bigger increment is obtained when both, production and saturation are assimilated. In addition, the ensemble improved its forecast capability the most, when saturation assimilation is included. Nevertheless, the ensemble expected NPV decreases after assimilation from the value obtained from the first development strategy optimization; this indicates an optimistic early NPV valuation due to the initial ensemble distributions spread. The study presents an asset simulation framework that could be used to evaluate data acquisition investments through the systematic modeling of reservoir uncertainties with in a decision oriented focus. This could include the inclusion of additional uncertain model parameters, the insertion of water injector and well conversions, the assimilation of saturations at different intervals, the change on the quality of the saturation maps assimilated, in addition to sensitivity studies of other economic constrains.
- North America > United States > Texas (0.94)
- Europe > Norway > North Sea > Central North Sea (0.28)
- Research Report > New Finding (0.34)
- Research Report > Experimental Study (0.34)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.46)
- North America > United States > Louisiana > Delhi Field (0.99)
- Europe > Norway > North Sea > Central North Sea > Utsira High > PL 501 > Block 16/5 > Johan Sverdrup Field > Zechstein Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > Utsira High > PL 501 > Block 16/5 > Johan Sverdrup Field > Viking Formation (0.99)
- (33 more...)
- Reservoir Description and Dynamics > Reservoir Simulation > History matching (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Four-dimensional and four-component seismic (1.00)
- (3 more...)
Small-Scale Fracture Conductivity Created by Modern Acid Fracture Fluids
Hill, Alfred Daniel (Texas A&M University) | Pournik, Maysam (Texas A&M University) | Zou, ChunLei (Schlumberger) | Malagon Nieto, Camilo (Texas A&M University) | Melendez, Maria Georgina (Texas A&M University) | Zhu, Ding (Texas A&M University) | Weng, Xiaowei (Schlumberger)
Abstract The effects of acid solutions injected into hydraulic fractures created in carbonate formations can be assessed at the laboratory scale in acid fracture conductivity tests that mimic the conditions in an actual acid fracture treatment. We conducted a series of acid fracture conductivity tests using a protocol that mimics the fluxes in a hydraulic fracture, both in the main flow direction along the fracture, and in the fluid loss direction. In our tests, the injection rate into the fracture is much higher than in many previous tests, and the fluid loss flux is controlled to match field fluid loss rates. We studied three commonly used acid fracturing fluids---an acid viscosified with polymer, an emulsified acid system, and an acid viscosified with surfactants---at elevated temperatures of 200ºF and 275ºF. The acid fracture conductivity apparatus is similar to a standard API fracture conductivity cell, but with a capacity to hold core samples that are 3 in. long in the leakoff direction. The long cores allow for better control of leakoff as the acid creates wormholes into the core samples. In these tests, acid was pumped through the fracture for contact times ranging from 15 to 60 minutes. After the fracture surfaces were carefully characterized with a surface profilometer, the fracture conductivity was measured at increments of closure stress, up to a maximum closure stress of 6,000 psi. In this paper, we present the results obtained from a series of experiments with these fluids using Indiana limestone and dolomite core samples. Among the findings: The fracture conductivity created did not show a general increase with acid contact time, and in fact decreased at higher contact times with some fluid systems. This suggests that optimal times of acid exposure in acid fracturing treatments exist. There were large differences in the conductivity created with the three acid systems tested. At 200ºF, the acids viscosified with polymer or surfactants created much higher conductivity than the emulsified acid system. The laboratory-scale acid fracture conductivities measured in these experiments do not agree with the predictions of the Nierode-Kruk correlation. Introduction Acid fracturing is a well stimulation process in which acid dissolution along the face of the hydraulically induced fracture is expected to create lasting conductivity after fracture closure. However, conductivity after fracture closure requires that the fracture face is non-uniformly etched by the acid while the strength of the rock is still maintained at high levels to withstand the closure stress. At low closure stress, the etched pattern of the fracture face should have a dominant influence on the resulting fracture conductivity as long as the strength of the rock can withstand the load. As the closure stress is increased, surface features along the fracture faces may be crushed and the fracture conductivity is more dependent on the rock strength than on the initial etching pattern. The success of the acid fracturing process depends highly on the resulting fracture conductivity which is very difficult to predict because it inherently depends on a stochastic process and is affected by a wide range of parameters. Most predictions of conductivity are made with the empirical correlation developed by Nierode and Kruk. This correlation was based on experiments using 1 inch diameter by 2 to 3 inch long fractured cores, with no fluid loss through the rock samples. The acid fluxes through the fracture in these experiments were much lower than expected in a field fracture. While there have been several other experimental studies done, they were either done at conditions that did not scale to field conditions or did not consider rock weakening or the etching pattern on resulting fracture conductivity while the effect of only a few parameters were studied in a limited number of experiments.
- Research Report > New Finding (0.88)
- Research Report > Experimental Study (0.88)