New Perspective in Regional and Residual Separation of Gravity and Magnetic Data Processing

Separation between Regional and Residual anomaly in Gravity and Magnetic data processing is very important to get the best result in geological interpretation. Several method were used to solve this problem like upward continuation and polynomial fitting. With the same principle, 2D FFT is applied by make an interactive tools based on Matlab Language Programming, named “Oasis Ala-Ala”. It adopt the algorithm from software Oasis. It started with make visualization map or the original data, then the map divide into some grids. Each of grid contain gravity or magnetic data. Then it transformed from special to wavenumber domain. After that, it convolve with our own filter matrix. And the last step is inverse it to get the regional and residual anomaly map. However, Matlab is powerful in facilitate this process in the GUI Toolbox. One important thing is the size of gravity and magnetic data. It will improve to Filter matrix size before do inverse process.

Prestack Seismic Inversion via Nonconvex L1-2 Regularization

Using seismic data, logging information, geological interpretation data, and petrophysical data, it is possible to estimate the stratigraphic texture and elastic parameters of a study area via a seismic inversion. As such, a seismic inversion is an indispensable tool in the field of oil and gas exploration and development. However, due to unknown natural factors, seismic inversions are often ill-conditioned problems. One way to work around this unknowable information is to determine the solution to the seismic inversion using regularization methods after adding further a priori constraints. In this study, the nonconvex L1−2 regularization method is innovatively applied to the three-parameter prestack amplitude variation angle (AVA) inversion. A forward model is first derived based on the Fatti approximate formula and then low-frequency models for P impedance, S impedance, and density are established using logging and horizon data. In the Bayesian inversion framework, we derive the objective function of the prestack AVA inversion. To further improve the accuracy and stability of the inversion results, we remove the correlations between the elastic parameters that act as initial constraints in the inversion. Then, the objective function is solved by the nonconvex L1−2 regularization method. Finally, we validate our inversion method by applying it to synthetic and observational data sets. The results show that our nonconvex L1−2 regularization seismic inversion method yields results that are highly accurate, laterally continuous, and can be used to identify and locate reservoir formation boundaries. Overall, our method will be a useful tool in future work focused on predicting the location of reservoirs.

High Performance Computing on the Cloud Successfully Deployed for 3D Geosteering and Reservoir Mapping While Drilling

The successful drilling of horizontal wells targeting reservoir zones of interest can be challenged by uncertainties in geological interpretation, identification of structure, and properties of reservoirs and fluid distribution. Optimizing the well placement of high-angle wells in order to intercept the sweet spots is crucial for the total hydrocarbon recovery in any development field. Thus, the geosteering domain was implemented to provide in real time a reservoir mapping characterization together with directional control to achieve the key performance objectives. In the past, many innovative technologies have been introduced in geosteering discipline, among them lately the deep EM directional resistivity tool that provides 1D formation resistivity mapping while drilling. However, despite the fact of delivering a multilayer mapping of the reservoir structure up to tens of meters away from wellbore, the real-time interpretation can be limited by this type of inversion. Since it is a 1D approach, these inversions map resistive boundaries on the vertical axis and assume infinite extend in all other directions. Consequently, in a complex geological setting, 1D approximation may fall short of properly describing the reservoir structure. This communication describes how the introduction of the 2D azimuthal resistivity inversions while drilling was conducted and details the various innovations required in the domains of downhole logging while drilling (LWD) measurements transmission in addition to adaptation of inversion methodology for real-time deployment, mainly through the use of high-performance cloud computing. The final enablement was the execution of automated workflows to process and deliver these advanced inversions into an integrated 3D geomodelling software within the turnaround time of drilling operations. This novel technology provides, while drilling, a better understanding of the 3D geological environment and fluid distribution with a deep depth of investigation, as well as the required information to make support for geosteering decisions for optimal well positioning. Initial field deployments were successfully conducted in horizontal wells, and three examples are presented here. Those real cases, executed with wire-drilled-pipe or mud-pulse telemetries, demonstrated the benefits of integrating 2D azimuthal inversions into the current geosteering workflow to provide a complete 3D structural understanding of the reservoir while drilling. This communication documents in detail how such an approach led to operational efficiency improvements in the form of 3D reservoir mapping in real-time, supporting a strategic change in the original well to turn toward the sweet spot, which was located sideways from the planned trajectory.

A New LWD Dual Imager with Incorporated Feedback Improves Image Quality in OBM: Some Learnings form Abu Dhabi Offshore Carbonates

Recent developments in Logging-While-Drilling (LWD) technology have enabled high-resolution borehole imaging in oil-base mud that used to be a long-standing challenge. New applications to enhance image interpretation and maintain feature-integrity were developed with feedback from Abu Dhabi field examples of recently deployed LWD dual imager where hostile drilling conditions impacted the high-resolution ultrasonic image quality. The new dual imager has 4 ultrasonic sensors and 2 electromagnetic sensors (for resistivity image) mounted on a 15-ft sub in the drilling bottom-hole assembly (BHA). It provides ultrasonic amplitude and travel-time images at two central frequencies in addition to apparent resistivity images composed of four operating frequency measurements. A long lateral of around 8000-ft was drilled with this new imager through challenging heterogeneous carbonates and data was analyzed for geological interpretation. Based on the feedback for data quality improvement in certain intervals, the impact of shock & vibration on high-resolution (0.2") ultrasonic images was analyzed in time domain with simulated data first to understand the behavior of causative factors independently. Afterwards, the new algorithms were developed and deployed to maintain feature integrity of the data. The validation on field-data provided much-needed validation for the results in hostile drilling conditions. Resistivity images provided all the bedding and textural information (vugs, stylolites) with high confidence images at around 0.8" resolution. Higher resolution (0.2") ultrasonic images provided concrete information about vugs distribution for secondary porosity with quantitative interpretation on vug-indices. In addition, feedback provided from real time data was incorporated in subsequent processing and development of an image processing app that effectively fixes the depth-filtering related to drilling-induced events and stick-slip. Re-processing of the data provided high quality images that were used for high-resolution geological interpretation. Confident feature recognition was input into interpretation application hitherto available only in water-base mud while drilling. Results of this study with feedback incorporated to field-data from Abu Dhabi helped better the geological interpretation in hostile drilling condition as well, minimizing the need for e-line imaging.

Rapid Reservoir Modelling: Sketch-Based Geological Modelling with Fast Flow Diagnostics

Rapid Reservoir Modelling (RRM) is a software tool that combines geological operators and a flow diagnostics module with sketch-based interface and modelling technology. The geological operators account for all interactions of stratigraphic surfaces and ensure that the resulting 3D models are stratigraphically valid. The geological operators allow users to sketch in any order, from oldest to youngest, from large to small, or free of any prescribed order, depending on data-driven or concept-driven uncertainty in interpretation. Flow diagnostics assessment of the sketched models enforces the link between geological interpretation and flow behaviour without using time-consuming and computationally expensive workflows. Output of RRM models includes static measures of facies architecture, flow diagnostics and model elements that can be exported to industry-standard software. A deep-water case is presented to show how assessing the impact of different scenarios at a prototyping stage allows users to make informed decisions about subsequent modelling efforts and approaches. Furthermore, RRM provides a valuable method for training or to develop geological interpretation skills, in front of an outcrop or directly on subsurface data.

Computer technology for interpreting vector measurements of the magnetic field

Computer technology is presented to solve the inverse problem of magnetic field vector measurements using software and algorithmic support for an automated system to interpret potential fields. The technology includes constructing a numerical model of the magnetic field of the studied area, forming an initial approximation model, assessing the depth of the sources and their magnetization. An approximation structure is used to describe the sources of anomalies (a set of uniformly magnetized polygonal prisms). To solve the problem, we used real vector measurements of the magnetic field by the components Xа, Ya, Zа, Та in the sections of Gruzsko South and Gruzsko Severnaya. Geologically, the area belongs to the central part of the Ukrainian Shield — the Kirovograd tectonic megablock. The area of work is confined to the Subotsko-Moshorin latitudinal fault zone. The possibility of comparing the results of the interpretation of anomalies on each profile by the components of the anomalous magnetic field increases the reliability of the geological interpretation of magnetic prospecting data compared to the interpretation of modular surveys. The presence of vector measurements greatly facilitates the ability to determine the parameters of anomalous objects, which makes it possible to obtain more reliable solutions to the inverse problem. The use of vector information makes it possible to localize geological sources more successfully, thereby reducing the amount of work.

Local Dynamic Updating Method of Orebody Model Based on Mesh Reconstruction and Mesh Deformation

In this paper, to update the orebody model based on the given interpreted geological information, we present a local dynamic updating method of the orebody model that allows the interactive construction of the constraint deformation conditions and the dynamic updating of the mesh model. The rules for constructing deformation constraints based on the control polylines are discussed. Because only part of the model is updated, the updated mesh is effective and the overall quality is satisfactory. Our main contribution is that we propose a local dynamic updating method for the orebody model based on mesh reconstruction and mesh deformation. This method can automatically update a given 3D orebody model based on a set of unordered geological interpretation lines. Moreover, we implement a deformation neighborhood region search method based on the specified ring radius and a local constrained mesh deformation algorithm for the orebody model. Finally, we test the method and show the model update results with real geological datasets, which proves that this method is effective for the local updating of orebody models.

Integrated geological interpretation of remote sensing data (Boysun structural-tectonic zone)

In recent years, remote sensing data are increasingly used in the practice of oil and gas prospecting. This article discusses the main methodological aspects of identifying oil and gas promising structures by using materials for interpreting remote sensing data and a complex of geological and geophysical data. Remotely sensed data exhibit a regional review of the various geological formations and tectonic fracture zone and faults that are otherwise not possible detection by human eyes on the ground. The method of structural interpretation space image allows you to: detail the internal structure of oil and gas regions; to reveal the position and features of the tectonic blocks, structures of the second and third (anticlines, synclines, monoclines, etc.) orders; identify major disruptive violations; identify chains of local structures; fix the transverse structural elements that determine tectonic fragmentation. By deciphering the remote sensing data, the distribution and nature of the lineament network marking disjunctive dislocations and zones of increased fracturing are revealed and analyzed, as well as ring structures are detected, which in most cases indicate local structures of the sedimentary cover at different depth sections. The lithology and lineament interpreted from these multi-level data were integrated with data collected from the ground.

Structural and geological studies in the Naryn and Atbashi depressions (Tien Shan) and geological interpretation of magnetotelluric data

The article presents the results of complex geological and geophysical studies in the Naryn depression and Atbashi depression in the Middle Tien Shan. They included the geological interpretation of new magnetotelluric data along the detailed profile crossing the key segment of the Tien Shan, and the study of the morphology and spatial position of the sedimentary cover and basement structures. The compilation of the results of structural-geological and geophysical studies makes it possible to create a 2D model of the upper-crust geological structure, consistent with the structure of the electrical conductivity to depths of about 10 km and to analyze the structural features of deeper horizons. Two types of structural patterns of the electric conductivity, corresponding to the sedimentary complexes of the cover and the folded-metamorphic complexes of the basement, have been identified. Sedimentary rock complexes in depressions have a high electrical conductivity and subhorizontal structure. The upper crust above the K2 density layer is characterized by an alternation of rocks volumes with contrasting conductivity, elongated vertically. The recorded structure of the field confirms the presence of steep zones of fluid permeability and fragmentation, noted earlier in seismic profiles and probably corresponding to the Paleozoic structures of fragmentation of the Earth’s crust, activated during Alpine orogeny. Comprehensive research allow to characterize the deformations of the Cenozoic sedimentary complex and the surface of the Paleozoic basement associated with the Alpine activation of the key segment of the Tien Shan.