Mud Diapirs Research Articles

The Cibarco anticline of the northernmost San Jacinto fold belt: Possible influence of mud diapirism on the Neogene to the recent evolution of the structure where the first oil and gas wells were drilled in Colombia

The Cibarco anticline, located in the northwestern South American convergent margin, is a long (approximately 40 km) and narrow (2.5 km wide), south-southwest–north-northeast-trending structure that separates two much wider depocenters, the Tubará-Juan de Acosta depocenter (approximately 20 km wide) to the west, and the Sabanalarga syncline (approximately 11 km wide) to the east. Detailed geologic surface mapping and subsurface seismic interpretation suggest that the formation and evolution of the Cibarco anticline have been strongly influenced by mud diapirism, which has been focused along a west-southwest–east-northeast-trending, inverted pre-Oligocene extensional fault. Seismic interpretation and outcrop analyses also confirmed that the source of mobile shales is the Upper Oligocene marlstones of the Lower Ciénaga de Oro Formation. We suggest that the main mechanism that caused the overpressures that triggered and controlled shale mobilization was disequilibrium compaction related to the sedimentary loading of impermeable seals and the shortening and inversion of pre-Oligocene extensional faults. Growth strata indicate that the Upper Oligocene mud started moving in Early Miocene times during the deposition of the thick Porquero mudstones, and it stopped migrating in Latest Miocene times. After an uplift and erosion event, mud diapirism remained inactive in the Early Miocene, and it was then reactivated in Late Pliocene times. Slight mud migration focused on the inverted fault continued throughout the Pleistocene and to the present. Today, the slight mud migration to the surface is observed in volcanoes located in the northern strand of the Cibarco anticline, although the rest of the anticline has become welded. Our new interpretations, carried out more than a century after the first hydrocarbon exploration activities began in Colombia, will hopefully allow us to increase our understanding of shale tectonics, petroleum systems, and plays in this portion of the convergent margin.

Mud diapirs in a continental extensional basin: 3D seismic interpretation of the Central Recôncavo Basin (northeast Brazil)

Mud diapirs are present in different tectonic environments around the globe and are particularly prevalent in large deltas. The onshore Jurassic-Cretaceous Recôncavo Basin in northeast Brazil represents an atypical example of mud diapir occurrence in a rift basin. The intensity of mud diapirism is different in the three sectors of the basin, with the central sector exhibiting the best development. In the southern sector, diapirism is less significant, and it is practically nonexistent in the northeast sector. The 3D seismic, outcrop, and well data are used to geomorphologically characterize the onshore mud diapirs in the central sector of the Recôncavo Basin and correlate them with the structural and morphological aspects of the basin, in addition to elucidating the possible origins of their movement. After seismic interpretation, four mud diapirs are identified in the study area: Apraius-Miranga Norte, Pedra do Salgado, Biriba, and Carijó. Two internal seismic facies are identified as F1 and F2, with F1 having more disruptive features and F2 being more reflection-free. The eastern diapirs, close to the border fault conglomerates, are dominated by disrupted seismic facies (F1). The diapiric movement is associated with paleoseismicity and the rupture of an ancient delta front, together with the rapid basinward advancement of conglomerates during an active rifting phase. The Biriba diapir is possibly the first to arise, followed by Carijó and Apraius-Miranga Norte, and finally, Pedra do Salgado; this variable timing influences the location and migration of the depocenters in the area.

The Mesozoic Subduction Zone over the Dongsha Waters of the South China Sea and Its Significance in Gas Hydrate Accumulation

The Mesozoic subduction zone over the Dongsha Waters (DSWs) of the South China Sea (SCS) is a part of the westward subduction of the ancient Pacific plate. Based on the comprehensive interpretation of deep reflection seismic profile data and polar magnetic anomaly data, and the zircon dating results of igneous rocks drilled from well LF35-1-1, the Mesozoic subduction zone in the northeast SCS is accurately identified, and a Mesozoic subduction model is proposed. The accretion wedges, trenches, and igneous rock zones together form the Mesozoic subduction zone. The evolution of the Mesozoic subduction zone can be divided into two stages: continental subduction during the Late Jurassic and continental collision during the late Cretaceous. The Mesozoic subduction zone controlled the structural pattern and evolution of the Chaoshan depression (CSD) during the Mesozoic and Neogene eras. The gas source of the hydrate comes from thermogenic gas, which is accompanied by mud diapir activity and migrates along the fault. The gas accumulates to form gas hydrates at the bottom of the stable domain; BSR can be seen above the mud diapir structure; that is, hydrate deposits are formed under the influence of mud diapir structures, belonging to a typical leakage type genesis model.

Automatic mud diapir detection using ANFIS expert systems algorithm; a case study in the Gorgan plain, Iran

Automatic mud diapir detection using ANFIS expert systems algorithm; a case study in the Gorgan plain, Iran

Preliminary analysis of the indicators and accumulation models of gas hydrates in the central Zhongjiannan Basin, western South China sea

The Zhongjiannan Basin is located in the western continental margin of the South China Sea (SCS). It was recently reported that there are geophysical indicators of gas hydrates in the northern Zhongjiannan Basin. However, due to the lack of in-depth studies, it remains unknown whether geophysical indicators of gas hydrates are also available in the central and southern Zhongjiannan Basin. Based on the latest geophysical data, we have identified the seismic anomaly features of gas hydrates and observed an obvious bottom simulating reflector (BSR) in the seismic section in the central Zhongjiannan Basin. Based on a comprehensive analysis of seismic characteristics, geological structures (e.g., faults, diapirs and pockmarks) and regional sedimentary conditions, we propose three accumulation models of gas hydrates in the central Zhongjiannan Basin. The first model is that gas develops in deep depression areas, migrates upwards from deep source rocks along vertical faults and forms reservoirs in shallow formations. The second model is that gas also forms in deep depression areas and rises along mud diapirs or gas chimneys from source rocks to shallow formations, with reservoirs formed above diapirs and/or mud volcanoes. The third model is that gas is mainly generated in slope areas where strata are relatively thin and fault structures are well developed; gas migrates upwards from source rocks along vertical faults, and reservoirs are formed beneath pockmarks. The geophysical indicators of gas hydrates are found for the first time in the central Zhongjiannan Basin of the SCS, yielding an important reference for further exploration and development.

Dynamic accumulation of a high-grade gas hydrate system: insights from the trial production gas hydrate reservoir in the Shenhu area, northern South China Sea

The ultimate enrichment level and quantity of gas hydrate resources are influenced by the dynamic process of accumulation and preservation. High-resolution 3-D seismic data, logging while drilling (LWD), pressured coring, and in situ testing were used to characterize the dynamic accumulation and preservation of the trial production high-grade gas hydrate reservoir (HGGHR) in the Shenhu area. Through seismic variance analysis and ant-tracking, we found that newly identified mud diapir-associated faults with three development stages controlled the migration and accumulation of gas hydrate and shifted the base of the gas hydrate stability zone (BGHSZ), resulting in dynamic accumulation and dissociation of gas hydrates. The recognized double bottom simulating reflectors (BSRs) were concluded to have been formed due to the shift of the BGHSZ caused by the variational equilibrium conditions. The interval between the double BSRs was inferred to be a disequilibrium zone where gas recycling occurred, contributing to the coexistence of gas hydrates and free gas and the dynamic formation of the HGGHR. Multiple gliding faults formed within the GHSZ in the late period have altered the HGGHR and control the present thickness and distribution of the gas hydrates and free gas in the hanging wall and footwall. Under the influence of geothermal fluids and the fault system associated with the mud diapir, the HGGHR experienced dynamic accumulation with three stages, including early accumulation, medium-term adjustment, and late alteration and preservation. We conclude that four factors affected the formation, distribution, and occurrence of the HGGHR: the geothermal fluids accompanying the deep mud diapir below the reservoir, the dual supply of thermogenic gas and biogenic gas, the recycling of hydrate gas beneath the BGHSZ, and the post-gas hydrate faults developed within the GHSZ. A geological model illustrating the dynamic formation of the trial production HGGHR was proposed, providing a reference for future exploration of HGGHRs with a great production potential in deepwater settings.

1300-m-High gas plume from pockmarks in the north Nansha waters, South China sea

The northeastern region of Nansha Waters, located in the southern margin of the South China Sea, is abundant in gas resources. However, it remains unclear if the central and northern areas of Nansha Waters possess gas resources and if there are any associated leaks. The Jiuzhang Basin is located in the northern Nansha Waters. Pre-stack depth migration, analysis of seismic attributes and multibeam data processing were conducted to image the seabed topography and backscatter intensity, as well as the seismic structure of the water and sedimentary layers in the Jiuzhang Basin. The result reveals a presence of large plumes, approximately 1500 m in width and up to 1300 m in height, from a pockmark. The plume is characterized by a strong seismic amplitude featuring chaotic reflections, a high instantaneous frequency (100–150 Hz), and a strong instantaneous amplitude. These seismic features commonly appear in hydrocarbon-bearing seawater, indicating that the plume is composed of gas. The relationship between the volume fraction of bubbles in the gas plumes and the amplitude of multi-channel seismic waves suggests that the volume fraction of bubbles within the gas plume can reach up to 5.0 × 10−3. Meanwhile, a new pockmark with a length of 248 m, a width of 90 m, and a depth of 20.4 m, and an abrupt 22 m drop in water depth of an existing pockmark are observed in the gas plume area. These observations, combined with the gas plume revealed by the multi-channel seismic collected in 2013 and multibeam collected in 2020, suggest a very strong and recently active gas leaks in the pockmark area of the northern Jiuzhang Basin. Furthermore, in the pockmark area, there are gas-bearing formations with weak reflections, and mud diapirs charactered by low seismic velocity, low amplitude chaotic reflections, and pulled up reflections on both sides, and faults extend to the seabed. These observations suggest that gas plume originate from deep strata of the northern Jiuzhang Basin. Large gas plumes and mud diapirs are often indicative of the existence of deep gas reservoirs. Therefore, the presence of such active gas plumes and mud diapirs in the northern region of the Jiuzhang Basin signifies the presence of abundant gas resources.

BSR Characteristics and Gas Hydrate Accumulation Mechanism in Qiongdongnan Basin

This paper makes full use of the high-precision three-dimensional seismic data in this area, combined with the differences in the source supply, migration and accumulation mode and occurrence characteristics of hydrate gas, analyzes and summarizes the gas hydrate migration and accumulation reservoir forming model in Qiongdongnan Basin. The hydrate migration and accumulation reservoir forming models in Qiongdongnan Basin are preliminarily divided into three categories: lower-generation and upper-storage type, self-generation and self-storage type and compound mixed type. The first two categories are further divided into five sub categories, of which the lower-generation and upper-storage types are divided into four sub categories: gas chimney dominated type, mud diapir dominated type, micro-fracture dominated type and fault dominated type. The self-generation and self-storage type can be regarded as: shallow in-situ migration and accumulation type.

A SYNTHESIS OF THE GEOLOGY AND PETROLEUM GEOLOGY OF THE IRANIAN PORTION OF THE SOUTH CASPIAN BASIN AND SURROUNDING AREAS

The South Caspian Basin, the northern Alborz Mountains, the Gorgan plain and the Moghan plain constitute the northernmost and youngest petroleum system in Iran. This region was part of the Paratethys realm from Oligocene to Pliocene time. The Oligocene – Miocene Maikop/Diatom Total Petroleum System of the South Caspian Basin produces major volumes of hydrocarbons in Azerbaijan and Turkmenistan, and the Iranian sector of the basin has consequently undergone exploration due to its generally similar geology. The 20 km thick, dominantly Cenozoic sedimentary cover in the basin is reduced to less than 3 km in the northern foothills of the Alborz Mountains, and scattered surface oil seepages in the latter region are believed to be generated by Cretaceous and Miocene source rocks. In the Moghan plain to the southwest of the South Caspian Basin, anticlinal folds of Oligo‐Miocene Zivar Formation sandstones may be prospective for hydrocarbon exploration. Mud volcanoes in the Gorgan plain and in adjacent offshore regions at the SE margin of the South Caspian Basin are associated with hydrocarbon seepages, and appear to be sourced by Cretaceous and Cenozoic shales and mudstones. Major structural features in the southern part of the South Caspian Basin include Cenozoic mud diapirs, folds and gravity structures.

Reservoir Potential Assessment of the Tortonian–Calabrian Sediments from Offshore Makran (Southwest Pakistan) through a Multidisciplinary Approach

AbstractThe Tortonian–Calabrian strata of Offshore Makran (Pakistan) is investigated for the purpose of reservoir assessment. The stratigraphy and petrophysics indicate that the Neogene sediments have tight reservoir potential with porosities in the range of 3%–9% and 40%–50% water saturation. The mineralogical cross plots indicate a mixed lithology with an abundance of dolomite and calcite, together with minor quartz content and shale. The seismic interpretation demonstrates medium–high amplitude reflection patterns, mud diapirs coupled with onlapping strata and the occurrence of bottom simulating reflectors (BSRs). The BSRs are characterized by diminished amplitude, low continuity and exhibiting acoustic blanking zones. The high formation pressure results indicate overpressure zones, suggesting the occurrence of overpressured shales in the Jal Pari‐1A. The presence of mud diapirs and gas chimneys are the result of tectonic forces acting at the junction of the Arabian, Indian and Eurasian plates, whereas, BSRs prove the existence of gas charged sediments supporting the formation of mud diapirism in the region. It is concluded that the high rates of sedimentation during the Neogene are likely to have contributed to the development of the high formation pressure. Revised mud weights, casing policies, pore pressure transients and geophysical inversion studies will help alleviate drilling risks in future exploration strategies.

Bouguer gravity anomalies and the three-dimensional density structure of a thick mudstone area: A case study of southwestern Taiwan

Gravity surveying is one of the best methods to deduce the subsurface structures in areas covered by thick mudstone in southwestern Taiwan where seismic data analysis is limited. We obtained regional and residual gravity anomalies from the Bouguer anomaly map using the wavelength filtering method to image the gravitational effects of subsurface sources at different depths. The distribution of the residual gravity anomalies corresponds well with the locations of faults and anticlines. Through the change of residual gravity anomalies due to sources at different depth, we estimated the inclination and extension of the anomalous bodies at different depths. Then, the three-dimensional density structure was inferred from inversion of the gravity data to reveal the distribution of mud diapirs and changes of depth to the basement. The positive residual gravity anomalies of approximately 1–2 mGal indicate that the material density of the diapirs is 0.1–0.2 g/cm3 higher than the surrounding rock. The origin of positive residual gravity anomalies can be roughly divided into three types corresponding to the possible subsurface structures. The depth of the positive gravity anomaly below the major anticlines is approximately 4–5 km, corresponding to the bottom of the mudstone formation, from which the mud diapirs may originate. The residual gravity anomaly pattern also indicates a connection of the Chegualin and Youchang faults and the nearly vertical Zuochen fault above 10 km depth. Finally, the low gravity in the Pingtung Plain results from the high-density contrasts on both sides of the two major faults and the deepening of the basement in the plain. The high-angle Chauchou fault, one of two major faults, was also identified at shallow depths based on analysis of the gravity data.

Quantitative Simulation of Gas Hydrate Formation and Accumulation with 3D Petroleum System Modeling in the Shenhu Area, Northern South China Sea

Gas hydrates have been considered as a new energy that could replace conventional fossil resources in the future because of their high energy density, environmental friendliness, and enormous reserves. To further analyze the potential distribution of gas hydrate stability zones (GHSZ) and the formation of a gas hydrate system in the Shenhu area of the South China Sea (SCS), a 3D petroleum simulation model (PSM) was built from 3D seismic interpretations and all available geological data. Based on the thermal calibration of the 3D model, the evolution of the GHSZ, hydrocarbon generation and migration, and the formation and accumulation of gas hydrates were simulated for the first time in the area. Thermal simulation shows that the methane source of gas hydrate originated from shallow biogenic gas and deep thermogenic gas. Most areas are dominated by shallow biogenic gas, while, only about 3% of the deep thermogenic gas derived from Enping Formation source rock and contributed to the gas hydrate formation within a few areas in the southeast. The thermogenic gas migrated vertically into the GHSZ through connecting faults, mud diapir, and/or gas chimney to form gas hydrate. The source rocks of the Wenchang Formation, a deep thermogenic gas source, began to enter the main hydrocarbon generation window at 28.4 Ma. The Enping source rock began to generate oil from 25 Ma on and gas from 16 Ma on. Since 5.3 Ma, most areas of the source rocks have generated a gas window, and only the shallower parts in the east still in the oil window, which had lasted until now. The shallow biogenic gas source rocks from the Hanjiang, Yuehai, and Wanshan formations generated gas in different periods, respectively. The Qionghai Formation began to generate hydrocarbon from 0.3 Ma and until now. Other results show that the GHSZ developed mainly during the Quaternary and Neogene (Wanshan Formation) and the GHSZ is thicker in the southern area and thinner in the northern part with a positive correlation with water depth. Starting at 11.6 Ma, the GHSZ developed in the Hanjiang Formation in the south of the Shenhu area and gradually expanded to the north to cover most of the study area at 5.3 Ma during the Yuehai Formation. From 1.8 Ma on, the GHSZ covered the entire study area. At the same time, the GHSZ in the Hanjiang Formation disappeared because of the change in temperature and pressure. At present, the GHSZ in the Yuehai Formation has disappeared, while the Quaternary and Wanshan are the two main formations for GHSZ development. The formation and distribution of gas hydrates are fundamentally controlled by the space-time coupling between the hydrocarbon generation and expulsion time and distribution of the GHSZ. The simulation results of gas hydrate accumulation and distribution were verified by drilling results and the matching rate is 84%. This is the first time that 3D simulation was successfully conducted with PSM technology in the Shenhu area and it provides important guidance for gas hydrate study in other areas of the SCS.

Evaluation of Natural Gas Hydrate Fault System: A Case from a Sag in Deep-Water Slope Area of the Northern South China Sea

AbstractThe fault system is one of the structural carrier systems of gas hydrate accumulation, which plays a vital role in controlling the distribution of natural gas hydrate (NGH) accumulation. The previous studies mainly focus on summarizing the vertical migration mode of high flux fluid along the fault with obvious geophysical response characteristics on the seismic profile, such as “fault with gas chimney,” “fault with mud diapir,” and “fault with submarine collapse”, but lack of evaluation methods for the fault carrier system. We use the X sag in the deep-water continental margin slope area of the northern South China Sea as an example to study the fault systems closely related to NGH. This paper puts to use attribute technologies, such as coherence, curvature, and fusion, to analyze the characteristics and combination of the fault systems. We discussed migration patterns and evaluation methods of dominant fault carrier systems. This research proves that the strike-slip fault system in the platform area can directly connect the gas source bed with high-quality hydrocarbon generation to the gas hydrate stability zone (GHSZ). The activity of this fault system is more conducive to the accumulation of hydrocarbon in the GHSZ. This area has a good site for pore-filling gas hydrate prospecting and a preferential favorable fault carrier system. The composite fault system, consisting of a normal dip-slip fault system and a polygonal fault system, in the slope area can jointly communicate the biogenic gas-rich reservoir. Its activity and well-migration performance are the main reasons for the submarine gas leakage and collapse. It is a secondary favorable fault carrier system in the study area. There may be massive and vein natural gas hydrate formation in fractures in the leakage passage, and pore-filled gas hydrate may exist in the submarine nonleakage area. In this work, a three-factor evaluation method of the fault carrier system is proposed for the first time. This method is of great significance for the evaluation and exploration of NGH reservoirs in the continental margin slope area of the northern South China Sea.

Mud Diapir or Fault‐Related Fold? On the Development of an Active Mud‐Cored Anticline Offshore Southwestern Taiwan

AbstractThere has been a controversial debate about the roles of diapiric folding versus fault‐related folding in mud‐cored anticlines. This study tackles this debate by looking into the structural developments in southwestern Taiwan. Among all the structures, the Liuchiu anticline is the only active structure exposed above sea level and therefore offers a unique opportunity to integrate land and marine data sets. On Liuchiu Island, we obtained the fold core geometry at the surface and identified three terrace groups with age constraints. In the offshore area, we obtained the fold limb geometry from seismic profiles. Given the tight fold shape and the asymmetric terrace tilting, we found that a hybrid fault tip fold‐fault propagation fold model can best explain the geologic and geomorphic features. In this regard, mud diapirism should be a secondary process, possibly along discrete patches of mobile shales to enhance fold amplification. Our model yields decreasing shortening rates from 0.7 mm/yr during the Plio‐Pleistocene to 0.375 mm/yr since 120 ka. The uplift rate however increases since the mid‐Holocene, which we tentatively attribute to larger mobile shale deformation triggered by earthquakes along the fault after the near‐fault fluids are drained. At the regional scale, we further suggest that the remaining plate convergence is absorbed by a few major structures west of Liuchiu Island.

Seismic Characteristics and Hydrocarbon Accumulation Associated with Mud Diapir Structures in a Superimposed Basin in the Southern South China Sea Margin

Seismic Characteristics and Hydrocarbon Accumulation Associated with Mud Diapir Structures in a Superimposed Basin in the Southern South China Sea Margin

A full interpretation applying a metaheuristic particle swarm for gravity data of an active mud diapir, SW Taiwan

An interpretation for the gravity anomalies is essential to visualize the horizontal and vertical extension of the subsurface intrusion like mud diapirs resembling dike-like geologic bodies. Therefore, the use of simple-geometrical resembling models helps to validate the subsurface targets. A particle optimization algorithm is one of the recently established metaheuristic algorithms, which is utilized in various geophysical applications and allows discovering and explaining the parameters of the buried geologic targets. Here, we have interpreted gravity response profiles for mud diapir, which close an expected two-dimensional (2D) inclined dikes by calculating the following parameters; amplitude coefficient (A), depths to top (h) and bottom (H), width (2b), inclination angle (θ), origin (d), and length of the body (L) that represents the difference between two depths using the particle optimization algorithm. The stability and efficacy of this study were checked on numerical examples without noise and with numerous levels of random noise (10% and 20%). Also, it tested on a gravity response for mud diapir from the south-western (SW) Taiwan and validated by seismic interpretation. The obtained results declared that the suggested algorithm works well even in the existence of noises. Furthermore, the results of the real case model are found in a respectable agreement with available geological and borehole information and other results from the published literature.

Origin of coseismic anelastic deformation during the 2016 Mw 6.4 Meinong Earthquake, Taiwan

An unexpectedly large uplift of 91 mm was detected by geodetic observations during the rupture of 2016 Mw 6.4 Meinong earthquake, Taiwan, which has been attributed as either a triggered anelastic and hydrologic related deformation from a proposed duplex/mud diapir or a triggered aseismic slip on a proposed backthrust. Here, using both high-rate GNSS and free-field strong motion data, we first estimated the coseismic source model. The locations of high PGV were inferred to explain the unexpected distribution of damaged buildings approximately 25–30 km west of the epicenter. Then, the aseismic surface displacements during the earthquake was differentiated using the coseismic source model. The aseismic extension of 3.8 μstrain is inferred at the unexpectedly large uplift region. Combining with local geology, residual gravity anomaly, seismic tomography, interseismic leveling vertical velocities, coseismic leveling uplifts and proposed Coulomb stress changes, the accelerated mud diapirism during the earthquake triggered by slip on the deep seismogenic fault was identified as the cause of unexpectedly large coseismic uplift.

Distribution and geological controls of the seabed fluid flow system, the central‐western Bohai Sea: A general overview

AbstractThorough understanding of seabed fluid flow system is of great significance to geohazard identification and hydrocarbon exploration as it can reshape the seabed and act as an indicator of subsurface hydrocarbon resources. For the first time, an integrated study of side‐scan sonar, single‐ and multi‐channel seismic data and magnetic data reveals a complex fluid flow system composed of various seafloor expressions (i.e. pockmarks and mounds) and shallow fluid migration pathways in the central‐west Bohai Sea off northeast China. Gas chimneys, mud diapirs and a dense network of Quaternary faults are the main fluid migration pathways in the shallow subsurface. The gas chimneys can be classified into three categories (Type A formed by relatively rapid gas escape, Type B formed by episodic fluid expulsion and Type C formed by fluid escape from mud diapirs), based on their distribution and seismic character, implying variability in the formation processes. Sediment remobilization and basement‐involved faults contribute to deep fluid migration into shallow depths. As a seal for up‐moving fluids, the nature and thickness of Holocene marine sediments generally decide the permeability and overburden pressure that may control the distribution of pockmarks and mounds since they are almost distributed above relatively thin Holocene deposits (thickness <20 m) and localized coarse surface sediments. The results of the interpretation gain an improved understanding of the geological processes controlling the genesis and spatial distribution of gas chimney formation and show the significance of gas chimney classification. The distribution pattern of different types of gas chimneys may signify the difference of geological background and fluid flow process, like fluid migration through faults or flow of mobilized sediments, that is crucial for the evaluation of global petroleum systems and Carbon Capture and Storage studies.

Automatic seismic image segmentation by introducing a novel strategy in histogram of oriented gradients

Automatic seismic image segmentation and further geological interpretation, requires accurate detection of the target's boundary through applying image analysis techniques. Various types of image segmentation and analysis methods are available for this purpose, using the texture attributes, the machine learning methods or the computer vision tools. The histogram of oriented gradients (HOG) as an advanced image analysis tool is frequently used in the pattern recognition investigations. Here a novel strategy in the extraction of the texture attributes based on using the concept of the HOG is introduced for automatic seismic image segmentation and properties extraction. The proposed strategy consists of extracting the HOG features, deriving statistical parameters related to the texture attributes and separating the target by integrating the selected images. To increase efficiency of the proposed strategy, a new parameter as the hybrid texture attribute is also introduced. The proposed method is applied on two geometrically simple and complex synthetic models and two field seismic data examples, containing saltbody and mud diapirs. The saltbody in the first selected field data example demonstrate a chaotic pattern with the unsharp boundary. The mud diapirs in the second field data example illustrate the mild chaotic pattern with interdigitated boundary and thin marginal flows. The result of applying the presented strategy on the both seismic images, compared to the result of the conventional interpretation methods, texture of attributes (TOG) and other textural attributes, revealed that it can be considered as an alternative for conventional image interpretation. However, it should be noted that at this stage, the presented method can be used for separating geological objects with any shape, different seismic patterns and sufficient contrast with surrounding media. However, it is not yet developed for fault detection and horizon auto tracking.

Seismic Signature Analysis for Clarification of Mud Volcanoes from the New Mud Diapirs Discovered at the NE-SW Moroccan Atlantic Margin

Our aim is to clarify mud volcanoes from the new mud diapirs resulting from the seismic attributes analysis applied to the low resolution Burmah oil “1973-1974” seismic data. The latter was carried out on the Larache and Tanger-Larache offshores from the NE-SW Atlantic margin. The high resolution seismic data was essential for this evaluation. In this case, we applied seismic signature analysis to four seismic profiles from the map of the seismic data set, which includes all new mud diapirs. This helped us to classify different types of mud diapirs within the seismic profiles. And as a result, six deep mud diapirs from the Prerifaine Nappe of Morocco, a shallow mud diapir, and four seafloor-piercing mud diapirs have been observed. Furthermore, the seafloor-piercing mud diapirs show a mushroom-shaped and conical-shaped cone. As they break through the seafloor, these kinds of cones characterize mud volcanoes. In this case, we may conclude that the resultant seafloor-piercing mud diapirs are likely to be mud volcanoes. However, more geological sampling and seafloor observation are still required.