Chen, Xin (BGP) | Wang, Guihai (CNODC) | Wang, Zhaofeng (CNODC) | Liu, Zundou (CNODC) | Liu, Zhaowei (CNODC) | Cui, Yi (CNODC) | Tian, Wenyuan (CNODC) | Wei, Xiaodong (BGP) | Hou, Liugen (BGP) | Yang, Ke (BGP) | Chen, Gang (BGP) | Xia, Yaliang (BGP) | Yan, Xiaohuan (BGP) | Zhang, Zeren (BGP) | Liu, Jingluan (BGP)
To improve the accuracy of permeability prediction, seismic constraint and sedimentary facies has often been adopted in conventional methods. However, it is porosity that both of them constrain, rather than permeability, and different pore structure with different permeability, the accuracy of permeability prediction cannot be radically improved. To address the problem of permeability prediction in carbonate reservoir, new permeability prediction technique workflow were summarized based on pore structure analysis and multi-parameters seismic inversion: division reservoir types based on the pore structure, construction of the rock types identification curve, carry out a rock type inversion and a porosity inversion constrained by seismic impedance respectively, and then get a final permeability prediction volume according to the porosity-permeability relationship and pore structure of core samples. It breaks the bottleneck that is difficult for seismic impedance (continuous variable) to constrain rock type (discrete variable), then constrains pore structure (continuous variable) related to rock type instead, and converts it into rock type using multi-parameters seismic inversion. According to the certification of new wells, this workflow have been applied successfully in carbonate reservoir of H oilfield in Middle East, it not only improves the prediction of rock type in space, but also permeability prediction accuracy.
Chen, Xin (BGP) | Zhang, Suhong (BGP) | Ou, Jin (CNODC) | Ye, Yufeng (CNODC) | Xu, Lei (CNODC) | Ma, Yingze (CNODC) | Wei, Xiaodong (BGP) | Yang, Ke (BGP) | Chen, Gang (BGP) | Zhou, Guofeng (BGP) | Xia, Yaliang (BGP) | Yan, Xiaohuan (BGP) | Zhang, Zeren (BGP) | Liu, Jingluan (BGP) | Zhou, Xiaoming (BGP)
In order to improve the accuracy of reservoir prediction results, the conventional method usually include seismic inversion, and seismic attribute analysis. Due to the limitation of the vertical resolution of seismic data, it is hard to identify the thin reservoir by seismic attributes directly. In order to improve the prediction accuracy of reservoir, this paper show a new reservoir characterization technique based on geological seismic conditioning. The new method mainly includes five steps. The first step is sedimentary facies classification based on the geological seismic analysis, such as core data, thin section analysis, FMI logging, NMR logging and conventional logging. The second step is modern sedimentary model optimization and forward modelling. In order to establish a reasonable sedimentary facies model, a similar barrier island modern sedimentary model was chosen. To understand the geological significance of seismic data, two different dominant frequency were designed for forward modelling based on the sedimentary facies model and petrophysical analysis. The third step is seismic conditioning under the guide of sedimentary facies model forward modelling. The next step is seismic constraint stochastic inversion, and the last step is reservoir characterization and new well confirm. The application of this method in A oilfield shows that the techniques not only improved the identification ability of the reprocessing seismic data, but also improved the prediction accuracy of the reservoir characterization results. This new reservoir characterization technique can integrated multidisplinary information, such as modern sedimentary model, well data and seismic data, to establish a reasonable sedimentary model, to enhance the resolution of seismic data by conditioning, and get an reasonable reservoir characterization results based on the seismic inversion.
Static methods are commonly used to analyze the reservoir connectivity. However, the results are dubious. In this paper, an integrated method for validating results is proposed by using dynamic data and reservoir simulation. Static methods used to analyze the reservoir connectivity include seismic inversion, well to well correlations, pressure gradient, oil-water contacts, fluid property and so on. However, the study results by static data are dubious. In order to validate and improve the understanding of reservoir connectivity, dynamic data and reservoir simulation was used. First, the reservoir connectivity was investigated with the static methods mentioned above. Second, the static model was built on the basis of the geology integrated study result. Third, by combining both results stated above, a dynamic model was established. Finally, the understanding of reservoir connectivity was reasonably and effectively improved by conducting the production history matching and adjusting the static parameters. During this process, first, an unreasonable understanding on reservoir connectivity was recognized; then, a modified and improved static model was updated for the simulated results better matching production data, where the reservoirs connectivity was also updated.
Reservoir connectivity was successfully characterized with the proposed method in application field in Iraq. Results show that (1) reservoir connectivity characterization by static methods only is often not correct for local area in case field, which is validated by the simulated WTHP of some wells much lower than the actual measured data; and (2) an updated reservoir connectivity is more correct and reliable, which can improve the matching between reservoir simulation results and production data. Dynamic data and reservoir simulation is a effective method to study the reservoir connectivity incorporated with static methods. The integrated method should be trend for the reservoir connectivity characterization.
She, Bin (University of Electronic Science and Technology of China) | Yaojun, Wang (University of Electronic Science and Technology of China) | Cheng, San (University of Electronic Science and Technology of China) | Hu, Guangmin (University of Electronic Science and Technology of China) | Liu, Wei (BGP) | Zhang, Yusheng (BGP)
AVO inversion problem is high-dimensional and ill-posed. In order to improve the stability and performance of the inversion procedure, we introduce the total variation (TV) regularization into AVO inversion. The inverted result is blocked and has more advantageous for interpretation. Then we illustrate that the sampling in the seismic data procedure can lead to complex shapes of the models, while the conventional TV regularization is not applicable for these conditions. Therefore, the high-order TV regularization scheme is proposed for the non-block-structured models. Because it can make full use of the structural features of the models to be inverted, the inversion results of this scheme can match the real models better. After using the sparse theory to demonstrate the advantages of the proposed method, we apply it to synthetic and real data to present the performance.
Presentation Date: Tuesday, September 26, 2017
Start Time: 1:50 PM
Location: Exhibit Hall C/D
Presentation Type: POSTER
Conventional seismic survey follows the principle of “Production after trial”. The acquisition parameters are mainly chosen based on the previous test points. The number of folds is determined mainly by the test line. However, the point test cannot fully and intuitively reflect the subsurface geological conditions in the segment. To carry out a line test, not only a long spread needs to be laid, a lot of corresponding source points have to be laid as well. For complex surface area with obstacles, the greater the surface space occupied by the source points for the test, the more permitting problems it will take, which affects the progress of the test. In this paper, a new test method is proposed. Without moving the spread, a rectangular area is chosen in the spread. In this a rectangular area, source points are laid with smaller source point interval for shooting to acquire single-shot data, which is stacked after NMO processing to get the CSP domain stacked sections for different folds. Based on the analytic comparison to the effect of these stacked sections, the folds to be used in the production is determined. In the view of vibroseis survey, the quantitative relationship among the number of vibrators, the folds and the S/N ratio can also be studied to provide a reliable basis for the optimization of the acquisition parameters.
Presentation Date: Thursday, September 28, 2017
Start Time: 8:30 AM
Presentation Type: ORAL
Complex structure, fault development and thin reservoirs are three main characteristics of LH oilfield in Eastern China. And the development is difficult due to the low resolution of surface seismic data in this area. To accurately evaluate and predict the reservoir, identify small faults and implement the micro structure, as well as predict the distribution range of the oil sand body, a 3D VSP survey was conducted. In this paper, the 3D VSP project in LH oilfield is taken as an example to demonstrate the 3D VSP technology and its application in structural imaging. After interpretation and fault recognition, small faults which were not seen on surface seismic data are shown up on VSP image. Analysis shows that the 3D VSP has a good impact on oil and gas exploration and development.
Presentation Date: Tuesday, September 26, 2017
Start Time: 1:50 PM
Presentation Type: ORAL
Wang, Yaojun (Center for Information Geoscience, University of Electronic Science and Technology of China (UESTC)) | Cheng, San (Center for Information Geoscience, University of Electronic Science and Technology of China (UESTC)) | She, Bin (Center for Information Geoscience, University of Electronic Science and Technology of China (UESTC)) | Li, Wenhao (Center for Information Geoscience, University of Electronic Science and Technology of China (UESTC)) | Hu, Guangmin (Center for Information Geoscience, University of Electronic Science and Technology of China (UESTC)) | Liu, Wei (BGP) | Wang, Ximing (BGP)
The laterally constrained multitrace impedance inversion (LCI) is superior to trace-by-trace inversion, because it can explore spatial coherence among traces and produce a more realistic image of geological structures. However, when the traces are numerous, we have to deal with a large-scale matrix in the multitrace inversion. As usual, this processing has expensive computational cost and high storage requirement, which makes the effectiveness and applicability of the existing multitrace inversion algorithm to be restricted. Here, we introduce a computationally well-behaved algorithm called blocky coordinate descent (BCD), to solve the equation of laterally constrained multitrace impedance inversion. The new method is fast and can be implemented without considering the size of the seismic data. In addition, in order to improve the fidelity of formation boundaries and obtain a more focused solution, we introduce a minimum gradient support (MGS) regularization into the BCD-based laterally constrained inversion (BCD-based LCI) and propose a new method called BCD-based sharp LCI. The new approach can resolve sharp layer boundaries and keep the spatial coherence. At last, we illustrate the capability of the proposed approach on synthetic data and field seismic data.
Presentation Date: Wednesday, September 27, 2017
Start Time: 3:55 PM
Presentation Type: ORAL
Absorption and attenuation properties, especially the attributes extracted from broadband seismic data acquired with low-frequency sources, have been widely used in reservoir prediction and hydrocarbon detection. An AVF (amplitude versus frequency) based technique is used to detect hydrocarbon in carbonate reservoirs in Block B at the eastern margin of the Precaspian Basin. We try to find the correlation between fluids and frequency-dependent amplitude by scanning the broadband seismic data (with the bandwidth of 1.5-96 Hz) in frequency domain and then determine the frequency band with the most significant hydrocarbon responses. The results of hydrocarbon detection have been verified by well drilling. Introduction Amplitude and frequency absorption and attenuation occurring in the process of seismic wave propagation in subsurface formations may be caused by seismic energy loss due to inter-solid, inter-fluid and solid-fluid friction or by scattering related to heterogeneity.
Shulu sag is located in southern Jizhong depression, which is one of the most important oil and gas exploration areas in Jizhong depression. According to the researches, the fractures developed extensively in the calcilutite reservoirs induce strong anisotropy and heterogeneity. The unclear mechanism of seismic wave propagation in fractured calcilutite reservoirs is an important factor of restricting exploration breakthrough. In this paper, we construct the fractured calcilutite reservoirs equivalent medium model based on the equivalent medium theory. Following this, we analysis calcilutite seismic response, P-wave anisotropy and S-wave splitting phenomenon in fractured calcilutite reservoirs in order to instruct oil and gas exploration of unconventional fractured calcilutite reservoirs.
Presentation Date: Wednesday, October 19, 2016
Start Time: 10:20:00 AM
Presentation Type: ORAL
The MH1 well on the western slopes in the northwestern margin of Mahu depression of Junggar Basin obtained high-yield industrial oil flow in the Triassic Baikouquan group, which reveals a good exploration prospect in this area. Studies have shown that the reservoir type is fractured-porous dual medium fault-lithologic reservoir. The use of post stack seismic data can just qualitatively predict the plane distribution of fractures, and the actual drilling condition and prediction results are on the contrary. In anisotropic in HTI medium, the presence of cracks can cause propagation characteristics differences in azimuth of seismic information, such as time difference and amplitude, which can be important information reflecting the presence of cracks from the seismic section. Through high-density wide-azimuth 3D seismic data, this paper analyzes the relationship among the azimuth angle, offset and anisotropic characteristics, predicts the intensity and direction of fractures in the study area, achieves the quantitative characterization of fracture , which correlate well with the drilling result. This study is funded by the research of “Xinjiang-Daqing” and “highdensity and wide-azimuth seismic exploration supporting technology research”.
As Guan Baowen and Su Peidong said that fractures can lead to changes in seismic wave energy, amplitude, frequency, phase and the absorption coefficient when seismic wave passes through the reservoir medium, which causes a change in the reflection characteristics and forms important information reflecting the presence of cracks on the seismic section. Currently ways to carry out pre-stack crack detection through seismic data is mainly based on the property that seismic attributes (time difference, amplitude, etc.) change with azimuth and P-wave azimuthal AVO to detect anisotropic of medium, as Qi Qing (2014) and Wang Peng (2014) discussed. These methods are mostly limited by original data with narrow azimuth, low fold and short offset question so that the reliability of the results of fracture detection is reduced.
The study area is located on the western slopes in the northwestern margin of Mahu depression of Junggar Basin, and it appears south to east monoclinic structure. The depth of target stratum is about 2900-3800m where strike-slip faults were widely developed which extend nearly EW with steep sections and vertical throw ranging from 5-20m. (figure1). The MH1 well have obtained high-yield industrial oil flow in the Triassic Baikouquan group with high reservoir pressure that the pressure coefficient achieved 1.53. The effective porosity of the reservoir was 3-9%, with an average permeability of 0.1-8mD. The comprehensive log interpretation result of MH1 well indicates that relatively developed fractures of the interest interval are the main controlling factor of the high-yield well. According to a general mechanism of fracture formation, it can be speculated that fractures may be more developed as close to the strike-slip faults.