Upper Formation Research Articles

Borehole-to-Surface Electrical Imaging Technology for Dynamic Monitoring of Underground Gas Storage and Case Study

Summary To solve the issue of seasonal gas peak shaving, building underground gas storage is an effective solution. Geophysical monitoring technology is necessary for dynamic gas storage management. However, as these technologies are not highly accurate in the lateral direction, new technologies need to be developed. In recent years, borehole-to-surface electrical imaging (BSEI) technology has been widely used in reservoir and fracturing monitoring. In the dynamic monitoring of gas storage, high-power direct current is applied to the borehole through the steel casing, and the potential is measured on the surface. Then, resistivity inversion is performed to analyze the transverse distribution of the injected gas. To prove the feasibility of monitoring injected gas, a 3D forward case is simulated using the finite difference method (FDM). The model-structure-constrained inversion approach is verified. Based on the forward simulation results and the formation pressure period, the gas storage observation scheme is designed. The case study shows that the gas storage inversion results constrained by the upper formation have a high resolution and clearly show the transverse boundary of the target reservoir, which is consistent with the fault boundary determined by seismic prospecting. Therefore, 3D resistivity imaging can clearly show the distribution of gas reservoirs during injection and production. This study shows that BSEI is an effective technique for dynamic monitoring of gas storage and has good application prospects.

Evaluation of Parent Well Depletion Effects on Fracture Geometry Based on Low-Frequency Distributed Acoustic Sensing in Hydraulic Fracture Test Site-2

Summary Low-frequency distributed acoustic sensing (LF-DAS) has recently received much attention for its ability to monitor fracture propagation at offset wells. Hydraulic Fracture Test Site-2 (HFTS-2), a Department of Energy–sponsored field-based research experiment, has acquired LF-DAS data sets during the stimulation of many horizontal wells in the Wolfcamp Formation of the Permian Basin. Over 100 stimulated stages with different completion designs in four horizontal wells were monitored by two horizontal offset wells and one vertical pilot hole with permanent fibers. The parent well depletion affected all four horizontal wells in almost half of their lateral section. Several studies have been performed on the acquired comprehensive data set. In this study, we apply our novel Green’s function-based inversion algorithm to calculate the fracture width of each stage and investigate the impact of parent well depletion on fracture geometry. The Green’s function-based inversion algorithm has been successfully applied to a few stages of field case studies. The Green’s function matrix was built based on linear elasticity theory (3D displacement discontinuity method) to relate the fracture openings with strain responses measured along the length of the fiber. This novel algorithm only relies on measured strain to solve fracture geometry at the monitoring well. Therefore, it is independent of the physics of the fracture propagation process and can be used to validate hydraulic fracture modeling results. Using our inversion algorithm, we can efficiently and quantitatively interpret LF-DAS data to provide information on fracture geometry and completion efficiency. We analyze more than 100 stages of the LF-DAS measurements obtained at the fiber wells B3H and B4H during B1H, B2H, and B4H stimulations. We apply our inversion algorithm for four data sets covering the stimulation of the abovementioned three wells. The fracture growth at stages in the parent well’s depleted zone is biased more toward upper formation and in the easterly direction. The fracture width at the stages in the parent well’s depletion zone is reduced compared to fracture widths at stages in the nondepleted zone irrespective of the monitoring well location relative to the treatment wells. This difference in fracture widths will affect the proppant distribution to a great extent, thereby affecting the effectiveness of the stimulation. We also illustrate the application of the inversion algorithm for stages that have both conventional fracture hits with “heart-shaped” signals as well as fracture reopening signals. Our inversion algorithm gives a reasonable estimate of the fracture width that aligns with the qualitative analysis of microseismic data sets and statistic summary of fracture hit numbers of HFTS-2. We believe that this quantitative study provides us with insights into the fracture geometry due to parent well depletion effects.

PALYNOLOGICAL EVENTS OF THE TALANG AKAR FORMATION IN THE ON-SHORE AREA OF THE SOUTH SUMATRA BASIN

South Sumatra has been well known as the one of the largest hydrocarbon producers in Indonesia. Due to its potentiality, South Sumatra has been explored since the Dutch era. Million barrels of oil have been pumped out from this area and many unpublished reports and papers have been made regarding the remaining reserve of this area. This study focuses on Talang Akar Formation which is considered as the main reservoir in South Sumatra. Talang Akar Formation is interpreted to be formed in a deltaic environment (De Coster, 1974). The deltaic sediment must have contained excellent palynomorph assemblage as demonstrated by the previous authors (Hasjim, 1993, Morley, 1995 and LEMIGAS 2001a, b and c). On the other hand, marine microfossils show poor recovery including foraminifers and nannoplankton. This condition is understandable as marine microfossils are difficult to develop in the transition environment. For this reason, palynology is intensively studied as a powerful tool to comprehend the stratigraphy of the Talang Akar Formation.The deposition of Talang Akar Formation was influenced by the tectonic event during Late Cretaceous to Early Tertiary which caused the occurrence of Semangko Dextral Fault (Suwidiyanto, 2003). This fault resulted in the formation of horst and graben which allowed sedimentation of Lahat Formation and the Lower Talang Akar Formation in the low topography. Subsequently, sea level increased rapidly drowning up the deposition center which resulted in the sedimentation of the Upper Talang Akar Formation and limestone Baturaja Formation (Suwidiyanto, 2003). Based on lithological character, Talang Akar Formation is separated into Great Sand Member (GRM) occupying lower part of this formation and Transition Member (TRM) situating in the upper formation. GRM was formed in the fluvial to delta plain environment, whilst TRM was deposited in delta plain to pro-delta environment (De Coster, 1974). The environmental change from fluvial-delta plain of GRM (non-marine) to delta plain-prodelta of TRM (nonmarine to transition) suggests the occurrence of transgressive phase. Palynologically, this change must be reflected in the palynological assemblage. In fact, TRM yields more brackish palynomorphs than those of GRM. In contrary, GRM especially those of river channel deposits are characterised by regular occurrence of riparian (freshwater) pollen such as Marginipollis concinus and Pandaniidites sp. (LEMIGAS, 2001a, b and c).Although palynological investigations were frequently conducted within the Talang Akar Formation, the results of these investigations were restricted on age interpretation and paleoenvironment analysis. There are more information can be obtained from the palynological data. Therefore, it is required extra efforts to elaborate data becoming useful information such as palynological event, sea level changes and paleoclimate. This study intends to explore the stratigraphy of the Talang Akar Formation based on its palynological and other micro-fossil content which focuses on palynological characteristic of the Talang Akar Formation, palynological event and other biostratigraphic information (zones, age and depositional environment).

Analysis of the Limit Support Pressure of a Shallow Shield Tunnel in Sandy Soil Considering the Influence of Seepage

The objective was to optimize the existing solution for the limit support pressure of a tunnel face. Firstly, based on the numerical simulation results, the existing three-dimensional analytical solution for pore water pressure distribution is expanded to a three-dimensional solution considering the pore water pressure distribution in the upper formation behind the tunnel face. Then, according to the results of physical model tests, a failure model considering the failure range in the upper formation behind the tunnel face is established, and the newly established three-dimensional solution for pore water pressure is introduced into the model, and then the limit effective support pressure of the tunnel face considering seepage is obtained by the method of soil–water joint calculation. Finally, the calculation results in this paper are compared with the experimental results, numerical simulation results and existing theoretical solutions. The major findings are as follows. The distribution of pore water pressure in the front and back strata above the tunnel face is basically symmetrical. The limit effective support pressure of the tunnel face will increase linearly with an increase in the hydraulic head difference between the tunnel face and the ground surface. The calculated results of the new limit equilibrium theory are obviously larger than those of the existing theory and numerical simulation and closer to the results of the physical model tests. Therefore, the new limit equilibrium model can better predict the limit effective support pressure of the tunnel face considering seepage and provide a reference for actual projects.

Application of Seismic Attribute and Spectral Decomposition: Example of Fluvial System During Miocene in Field A, Malay Basin

Stratigraphic channels in field A Malay Basin including those with reservoir potential have been defined seismically. There were two exploration wells in field a however, the wells were abandoned due to low structural relief and volume were below economic criteria. This study discusses how seismic attribute and spectral decomposition give geomorphological information in different stratigraphic levels of Miocene age at Top F, H, I, Group I-50 and I-60. Facies analysis, seismic attribute, spectral decomposition and colour blending were implemented to identify hydrocarbon potential in stratigraphic traps and to enhance seismic resolution. Channel anomalies can be identified in seismic reflections characterized by high-amplitude events with chaotic reflections. Numerous sub-parallel reflection with high amplitude is observed in the upper formation. Several seismic attributes were used from the 3D seismic dataset to identify the geomorphologic features, potential reservoir variations, besides distribution and to extract the anomalies. Physical attributes which are related to amplitude, frequency, phase and their derivative were used including variance, instantaneous frequency, sweetness and spectral decomposition. Sweetness is the combination of lateral continuity and reflection strength. High reflection strength indicates maximum amplitude of the largest peak or through of real trace. This is especially, true when an event is a composite reflection. Amplitude attribute provides better spatial definition of events and bright spots could be enhanced. Instantaneous frequency shows composite frequency of the individual reflections contributing to a particular reflector. This composite is a useful correlation tool. Rapid changes in frequency are sometimes indicator of pinchouts such as oil/gas and water contacts. Low frequency anomalies are observed in zones below hydrocarbon reservoirs. Meanwhile, instantaneous phase is useful in stratigraphic analysis of certain sections because the sharp zero crossings that results may emphasize lateral discontinuities, pinchouts and angularities. The combination of attribute analysis and spectral decomposition aids the interpretation and identification of some channel patterns and channel distribution. Two methods of spectral decomposition are used Short Time Fourier Transform (STFT) and S-transform which focus on spatial and temporal range, respectively. Red Green Blue (RGB) colour blending represents different frequency ranges of low, mid and high frequency bands and display as a single image. This method reveals additional information such as depositional elements, anomaly identification, bed thickness, presence of fluids and help to resolve petrophysical heterogeneity. This study reveals that there are strong evidences of hydrocarbon potential in stratigraphic traps for further exploration within the study area. © Medwell Journals, 2019.

Does Neoproterozoic Nam Co formation in Northwest Vietnam belong to South China or Indochina?

The Nam Co belt is located to the northeast of Song Ma fault in Northwestern Vietnam. The nature of the Precambrian basement rocks in this area and its tectonic attribute have still been controversial. In this study, zircon U-Pb-Hf isotopic compositions and whole rock geochemical compositions of meta-sedimentary rocks from the Nam Co Formation in this belt have been integrated to reveal the components and tectonic setting of the formation of the basement rocks in the Nam Co belt. Zircon U-Pb dating results show that the Nam Co Formation is of middle-late Neoproterozoic age. The lower Nam Co Formation probably formed between 821 and 726 Ma, and the upper Formation was deposited later than 726–721 Ma. The sedimentary rocks from the lower and upper Nam Co formations are characterized by numerous Neoproterozoic (900–800 Ma) detrital materials, but the upper part contains more Meso- to Paleoproterozoic sediments than the lower part. Detrital zircon age distribution and Hf-isotope compositions of the Nam Co Formation are similar to those of Neoproterozoic sedimentary rocks in the southern Yangtze Block. Both zircon U-Pb-Hf isotopic and whole rock geochemical data suggest that the source materials of the Neoproterozoic Nam Co Formation were dominated by felsic rocks with minor mafic materials, and the detrital materials were mainly derived from the Jiangnan Orogenic Belt in the southern Yangtze Block, with minor contribution from the Panxi belt in the western Yangtze Block, Ailaoshan-Song Hong and Phan Si Pan belts. The lower Nam Co Formation contains more sediments derived from the Panxi belt than the upper part. The middle-late Neoproterozoic Nam Co Formation probably was deposited in a continental extensional basin, and the sedimentation environment in later period (<726–721 Ma) was more stable. Integration of our data with other lines of evidence suggests that the Nam Co Formation belongs to the basement of the Yangtze Block, and the Nam Co belt was originally located in the southwest corner of the Yangtze Block. This further suggests that the Song Ma fault probably is the boundary between the South China and Indochina blocks.

Failure mechanism of a mudstone slope embedded with steep anti-dip layered sandstones: case of the 2016 Yanchao catastrophic landslide in Taiwan

On September 28, 2016, the torrential rainfall carried by Typhoon Megi induced a catastrophic mudstone landslide in the Yanchao District of Kaohsiung City, Taiwan. The total volume of the sliding mass was approximately 8700 m3, which blocked an industrial road and displaced a duplex house in the downslope, leading to three deaths. Unprecedentedly, the 2016 Yanchao landslide was large and quickly raised public awareness regarding the possibility of large landslides that could occur in the nearby mudstone areas. Based on field surveys, topographic and geological maps, unmanned aerial vehicle (UAV) photography, and remote-sensing imagery, the failure mechanism of the 2016 Yanchao landslide is described in this study. The results revealed that steep anti-dip layered sandstones embedded with the mudstones play a critical role in large, rainfall-induced landslides. In the case of Yanchao landslide, the bedding joint between two formations was associated with the runoff infiltrating the low permeability mudstone. The kinematic process of the landslide consisted of two phases: a circular failure in the lower formation (alternation of mudstone and sandstone) and the subsequent regressive failure in upper formation (thick sandstone interbedded with mudstone). This study discloses the role of steep anti-dip layered sandstone influencing mudstone slope failure behaviors and presents a preliminary guide for assessing large, rainfall-induced landslides in mudstones. The results could also provide useful information for calibrating the numerical modeling of large landslides that may occur in the mudstone area in the future.

Numerical Study of a Flow Field Near the Bit for a Coiled-Tubing Partial Underbalanced Drilling Method

A new drilling method called coiled-tubing partial underbalanced drilling (CT-PUBD) was proposed in this paper. The method is not only able to enhance rate of penetration (ROP) just like the conventional underbalanced drilling technology but can also maintain borehole stability in the upper formation. In the new method, the wellbore pressure system is divided into two parts by a packer: (1) normal pressure system in the upper formation used to balance formation pressure and maintain borehole stability and (2) an underbalanced pressure system in the annulus near the bit used to enhance ROP. Because the pressure system and the circulation system are different, the cuttings transportation process of the method is different from the conventional way. Therefore, it is essential to study how to carry cuttings away efficiently. The flow field and cuttings distribution in the annulus near the bit were analyzed by computational fluid dynamic (CFD) methods. Cuttings transportation trajectory, velocity distribution, and cuttings concentration distribution were obtained under different holes’ parameters of the backflow device (including holes number, diameter, distance, and angle) and different drilling fluid viscosities. The results show that these parameters all have influence on cuttings carrying efficiency, and the most influential parameters are viscosity, angle, and diameter. According to the result of an orthogonal test, a suitable combination of the holes’ parameters was obtained. In the combination, the value of holes number, diameter, distance, and angle is 4, 50 mm, 300 mm, and 120 deg, respectively. This paper provides a theoretical basis for an optimization design of the new method.

Peri-Laurentian, Pinwarian-age oceanic arc crust preserved in the Grenville Province: Insights from the Escoumins supracrustal belt

The remnants of an island arc system of Pinwarian age, the Escoumins supracrustal belt (ESB), are exposed for over 100 km in the Low-pressure belt of the Central Grenville Province (Canada), and are part of the Quebecia terrane. The ESB mainly consists of amphibolite-facies supracrustal rocks with well preserved primary textures (Saint-Siméon Group; SSG), and their plutonic counterpart (Tadoussac Intrusive Suite; TIS) that provide a record of the evolution of a Mesoproterozoic arc system. Granodiorite (1502 ± 6 Ma) and tonalite of the TIS have calc-alkalic oceanic arc signatures, positive εNd (+2.66) with old model age (1672 Ma) consistent with remelting of previously formed juvenile mafic crust and interaction with an older crustal component, and are crosscut by younger within-plate granitoids. Tectonically above the TIS, the lowest formation of the SSG (Saint-Paul-du-Nord) consists of sedimentary, and minor basalt, intruded by syn-volcanic juvenile (εNd = +5.21) tholeiitic gabbro and is interpreted to represent the remnants of an oceanic basin adjacent to an arc. The middle formation (Moulin-à-Baude) records an evolution from: (a) subalkaline tholeiitic to transitional arc basaltic andesite, basalt, and minor calc-alkalic volcanic arc 1492 ± 3 Ma dacite with crustal-derived signature (εNd = −0.77, model age of 1936 Ma), to (b) transitional to tholeiitic dacite–rhyodacite and 1464 + 38/−32 Ma rhyolite, and (c) subalkaline juvenile (εNd = +3.91–+4.92) tholeiitic basalts and FeTi basalts of arc rift and back-arc affinities. This formation is interpreted to represent an oceanic arc undergoing rifting. Finally, the upper formation (Port-aux-Quilles) is composed of epiclastic sedimentary rocks with detrital zircon of Laurentian affinities, indicating proximity of the arc to Laurentia, but dominated by 1.5–1.47 Ga ages, showing a maximum age of deposition of 1476 ± 10 Ma. The εNd and Nd-model ages indicate an association of mixed crustal and mantle-derived signatures typical of Quebecia crust combined with younger depleted mantle-derived basaltic magma. The data provide new insights on the organisation of Quebecia, and show that crust formed in an oceanic arc setting during late Geon 15 to Geon 14 constitutes a significant component of the central Grenville Province.

Geology of Wadi Ka'am and Ka'am Dam Area, North Western of Libya

This research is an attempt to investigate the different geological features of Wadi Ka'am area located along the Mediterranean coast about 25 km west of Khoms City. Geomorphologic, stratigraphic, and structural investigations were carried out. The most important geomorphologic features of the study area include the Wadi Ka'am tributaries, Targhlat, and Al-chusaiha as well as another minor wadi transect of Wadi Ka'am. The wadi is characterized by steep sides due to structural effects. Wadi Ka'am is surrounded by rocky cliffs and saddle areas. The conjunction area of Wadi Ka'am tributaries forms Ka'am Lake where the Wadi Ka'am Dam was built. Terrace areas in the form of steps were formed as a result of water erosion action and may remark water level fluctuations of the lake. A number of internal lakes were formed in low laying areas due to confinement of water in the direction of discharge areas of the wadi. Sand bars (spites) were formed parallel to Wadi stream as a result of decreasing flow of water and hence deposition. Mud cracks were formed in places where muddy areas of the wadi become dried. The highly curved stream meanders of Wadi Al-Chusaiha may indicate the maturity stage of the wadi. Field observations conclude that the stratigraphic succession of the area is represented by the Triassic rocks (Abu Shaybah Formation) made up of continental horizontal-bedded sandstone intercalated with siltstone and mudstone. This is followed by Cretaceous rocks which are separated by an unconformity from the underlying Abu Shaybah sandstone. Cretaceous rocks may have distinguished into two formations: the lower is Sidi As Said Formation which is distinguished into Ain Tobi Member at the base (Dolomitic Limestone) and Yefren Marl Member on the top (Marl with claystone and gypsum crystals as well as Oyster bearing horizons), and the upper Formation is Nalut Formation (Dolomitic Limestone to Dolomite with chert layers and nodules). The two Cretaceous Formations were separated by a distinct para-conformity. The structural investigation was focused on measurements of joint and fault directions in the entire area of study and may conclude that the western stratigraphic succession of Wadi Ka'am is represented by Sidi As Said Formation (Yefren Marl Member) followed up by the dolomitic Limestone of Nalut Formation, while the eastern stratigraphic succession is represented by the Triassic Abu Shaybah continental sandstones at the base followed up by the lower part of Cretaceous rocks of Ain Tobi Dolomite. This distribution may indicate the presence of a N58E- S58W directed fault (the fault is thrown to NW). The prevailing direction of faults affecting the western Wadi Ka'am area is generally parallel to the prevailing extent of joints (N32W-S32E). In general, the study area is affected by two prevailing fault directions, the first which is the older and extended (N32W-S32E) where the fault is thrown toward NE and appears in the form of a step fault. The second is relatively younger and represents the Wadi Ka'am stream directed (N58E-S58W) where the fault is thrown toward NE. As a result of structural effects, the flow direction of Wadi Ka'am is N58E.

Microstructural investigation of gas shale in Longmaxi Formation, Lower Silurian, NE Sichuan Basin, China

The purpose of this paper is to probe into the nature and variability in vertical microstructure within Longmaxi gas shales of well WX2, Lower Silurian, located in the NE Sichuan Basin of China. To understand the pore system of these rocks, the total porosity, pore size distribution (PSD), surface area, organic geochemistry, and mineralogy, some image analyses by electron microscopy are performed. The obtained results indicated the following. (1) Gas shales have a complex pore structure. Total porosity from helium pycnometry ranges between 0.75% and 4.62%. Total organic content ranges between 3.4 wt.% and 11 wt.%, and vitrinite reflectance measured between 2.5% and 3.1%. The gas shales are quartz and clay rich. (2) Focused ion beam milling and field emission scanning electron microscopy provide high-resolution images of pores distribution and types. Three primary types of pores, organic matter (OM)-hosted pores, mineral-hosted pores, and micro-fractures, and 11 subgroups have been recognized. (3) The N2 isotherm curves are grouped into two types, II b as well as IV a, with the hysteresis loop belonging to Type B, reflecting the morphology of slits pores, and Type A, presenting cylinder pores. Combination of N2 and CO2 isotherm curve shows bimodal in two diameter sections, 0.3–1 nm and 2–5 nm, revealing meso-pores play important role in pore volume, whereas the micro-pores have great influence on pore specific surface area. (4) Total organic carbon (TOC) is considered to be the dominant contributor to total porosity and pore types, with the proportion of OM-hosted pores following the upward decreasing tendency of TOC. In plane, pore types are controlled by sedimentary facies. The OM-hosted pores are more prevalent in deep shelf facies within lower part of shale other than upper formation, instead of shallow shelf facies.

On identifying the formation pressure and filtration coefficients of two gaz-bearing formations

In the practice of gas field exploitation, there arises a problem of the production rates calculation for two gas-bearing formations opened by a single well. Its solution requires knowledge of the formation pressures and flow coefficients. While solving the problem, an important concept of the turning points has been introduced. They play a key role in developing a system of equations. In practice, no information on the formation flow coefficients and pressures is available; therefore, a question now arises of how they can be determined. It is possible to use downhole measurements, although doing this appears to be technically challenging. Wellhead measurements are simpler, but they provide only total production rate values under a fixed wellhead pressure. In [9], the authors are of the opinion that “measuring the flow coefficients of two gas-bearing formations opened by a single well without downhole measurements is currently impossible.” The problem under studying may have 13 different variants of setting up, depending on the placement of the wellhead pressure that is measured with respect to the turning points. It is unknown in advance which of the aforementioned variants is the case while measuring; therefore, it is necessary to study each of them individually. One of the most difficult cases is considered in the present article. Mathematically, the problem is reduced to solving a system of equations with 30 unknown quantities, and only 6 out of these equations are linear. Among the unknowns, there are the formation pressure and flow coefficients 3+3=6 of the upper and lower formations as well as 24 unknowns at each formation flow rate measuring: 6+6=12 and 6+6=12 wellbore pressures. It is reasonable to take the upper formation flow rates as the main unknowns in 1, 3, and 5 measurements, in which case the unknown formation pressures and flow coefficients are determined: they turn out to be the functions of the main unknowns, which in their turn satisfy a system of a three nonlinear equations’ polynomial over the first unknown of the seventh degree. Therewith, it is shown that two other main parameters are changed within the bounded domain, the boundary of which is explicitly described. This fact significantly simplifies solving the problem, whereas the desired formation pressures and filtration coefficients are a priori unbounded.

Drilling Engineering Design and Construction of Well Dong 11

The planned depth of well Dong 11 is 5,780 m, many complicated conditions may exist in the drilling process of this well, such as loose cementation and high risk of hole collapse in the upper formation, leakage of Cretaceous strata, caving mudstone in Jurassic, possible high-pressured saltwater zone and hydrocarbon zone in Sangonghe formation. In addition, this block is located in fault ruptured zone. Based on the above problems, casing program design, BHA design, drill bit selection, drilling fluid design and the cementing design was optimized and the drilling engineering design and site construction of the well was introduced. No complicated condition occurred during the whole well construction. PDC bit was used in the upper well section and PDC bit combined with screw drilling technology was used in lower well section, the average rate of penetration is 4.77 m/h, compared with the offset wells, the drilling speed increased obviously and the good hole diameter validates the serviceability of a strong inhibitive heat-resisting plugging polymer anti-collapse drilling fluid system in this area.

Morphological features of Delphinium sergii Wissjul. leaves in ontogeny

There are represented results of the study on leaf shape and its morphological diversity of the Delphinium sergii Wissjul. which is an endemic species of Eastern Black Sea Coast and was introduced in the culture at the M.M. Gryshko National Botanical Garden NAS of Ukraine. It is found that D. sergii is characterized by heterophylly and morphological variability of leaf blades which is manifested during ontogeny, in process of formation of its vegetative and generative shoots. The correlation of the dissection degree of the leaf blades with their formation and age has been established. More deeply dissected leaves are «older» while with complete laminas are more «younger». During the ontogenesis firstly occurs the complication of a simple lamina in seedlings by its division into segments. And, as a result, along the shoot the complication from lower to middle formations and further simplification of leaf structure in upper formation in generative individuals is observed. Formation of different by shape leaves in individuals of the same age stage as well as of the same age depends from conditions of lighting, soil moisture, crop density, and genetic heterogeneity, and therefore – from morphological plasticity of individuals in different conditions of growth.

Stratigraphic evidence for development of Aptian intrashelf basin in the Zagros area, eastern Fars Province, SW Iran

?The Lower Cretaceous of the Arabian Platform is renowned for the development of intrashelf basins. The study area is located in eastern Fars Province on the northeast Arabian plate and has experienced this environmental condition. The present study investigated two surface sections (Genau and Anguru) of the Dariyan Formation and compared the results with three neighboring wells in eastern Fars (eastern Zagros Fold Belt) in southern Iran to determine the development of rudist-bearing carbonates and intrashelf basin sediments. The Dariyan Formation was deposited in the Aptian as shallow-to-deep water carbonate facies. Lagoon, rudist banks/barriers, and open marine/basinal facies and six microfacies types have been distinguished. In the Genau section, the upper formation contains shallow rudistid limestone separated from the orbitolinid limestone of the lower formation by a deep pelagic unit. The pelagic sets disappear toward the Anguru section, but the rudistid unit remains. Abrupt changes were observed from shallow rudist facies to deep planktonic foraminifer facies. Comparison of the surface and subsurface sections (wells) suggests an intrashelf carbonate depositional model for the Dariyan Formation in the eastern Fars area. The term "Genau intrashelf" is proposed for this intrashelf basin surrounded by a shallow ramp. This intrashelf appears to be a northern subbasin of the Bab basin of the southern Persian Gulf. Extension of the Genau intrashelf subbasin and development of rudists around the margins of this intrashelf can be defined by tracing changes in the lateral facies of the Dariyan Formation.

The first record of an ornithomimosaurian dinosaur from the Upper Cretaceous of Japan

Ornithomimosaurs have unusual characters among theropod dinosaurs, and many records of these animals have been reported previously from Asia and North America. However, the fossil record of ornithomimosaurs is limited and was not known from the Upper Cretaceous in Japan despite its many dinosaur discoveries. Here, the first fossil of an ornithomimosaurian dinosaur from the Upper Cretaceous in Japan is described from the Upper Formation of the Mifune Group in Kumamoto Prefecture, Southwest Japan. This new discovery indicates the existence of ornithomimosaurs in the Late Cretaceous coastal areas of East Asia under a semi-arid climate. The occurrences of ornithomimosaur fossils described here are consistent with the presence of many fossil records from a dry climate rather than the humid conditions in the Cretaceous deposits of Asian mainland today.

A New Assisted History Matching Approach for Complex Reservoirs

This article describes the integration of mathematical models (Simplex and steepest descent algorithm) with global modification (through deeply geological studies) to increase the efficiency of history matching. This method can take full advantage of the gradient-based method (fast rate of convergence) and guarantee of finding a global minimum for inverse problems. The above method is applied to the Lower Miocene reservoir at White Tiger field, a highly heterogeneous reservoir, which has been producing under a naturally edge-water mechanism. A model that covers the upper formation of White Tiger field with 27 production wells and 8 injection wells is conditioned to 23 years of production history. The new assisted history matching approach provides an excellent match between simulation results and production data.

Estimating porosity and solid dielectric permittivity in the Miami Limestone using high‐frequency ground penetrating radar (GPR) measurements at the laboratory scale

AbstractSubsurface water flow in South Florida is largely controlled by the heterogeneous nature of the karst limestone in the Biscayne aquifer and its upper formation, the Miami Limestone. These heterogeneities are amplified by dissolution structures that induce changes in the aquifer's material and physical properties (i.e., porosity and dielectric permittivity) and create preferential flow paths. Understanding such patterns are critical for the development of realistic groundwater flow models, particularly in the Everglades, where restoration of hydrological conditions is intended. In this work, we used noninvasive ground penetrating radar (GPR) to estimate the spatial variability in porosity and the dielectric permittivity of the solid phase of the limestone at centimeter‐scale resolution to evaluate the potential for field‐based GPR studies. A laboratory setup that included high‐frequency GPR measurements under completely unsaturated and saturated conditions was used to estimate changes in electromagnetic wave velocity through Miami Limestone samples. The Complex Refractive Index Model was used to derive estimates of porosity and dielectric permittivity of the solid phase of the limestone. Porosity estimates of the samples ranged between 45.2 and 66.0% and showed good correspondence with estimates of porosity using analytical and digital image techniques. Solid dielectric permittivity values ranged between 7.0 and 13.0. This study shows the ability of GPR to image the spatial variability of porosity and dielectric permittivity in the Miami Limestone and shows potential for expanding these results to larger scales and other karst aquifers.

Characteristics of Deep Abnormal High Pressure and its Controlling on Hydrocarbon Accumulation in Zhanhua Sag

Study on abnormal pressure of sedimentary basin is of great significance. According to the ultrasonic time difference method and measured practical data, some sectional and planar pressure distribution of Zhanhua Sag are obtained while most belong to overpressure, and the pressure distribution and the formation mechanism of high pressure are also analyzed. It is showed that the pore fluid pressure of Es3 and the upper part of Es4 members are higher in Bonan subsag and Gubei subsag and the distribution of abnormal high pressure reached a maximum at the early Es3. The disequilibrium compaction, hydrocarbon generation and some clay mineral dehydration are suggested to contribute to the formation of normal high pressure, including the rapid deposition as one of the most key factor. The lower part of Es3 and Es4 themselves within the deep high pressure system, as good lithologic reservoirs, can transport oil to the upper formation by episodic release to form allochthonous atmospheric hydrocarbon reservoirs.

Research and Application of Gas-lift Reverse Circulation Drilling Technology to Geothermal Well Construction in Dalian Jiaoliu Island

This paper describes the principle of air-lift reverse circulation drilling, and its process feature, equipment selection, drilling assembly, drilling parameters and technical measures. Using the air-lift reverse circulation drilling, combined with geothermal well construction project in Dalian, a good solution was presented to the hole wall's stability problem that cannot be resolved by the conventional normal circulation and technology casing in that complex formation where are water bursting in the upper formation and collapse and falling in the lower strata.