Volcanic Rock Reservoirs Research Articles

Characteristics and prediction of weathered volcanic rock reservoirs: A case study of Carboniferous rocks in Zhongguai paleouplift of Junggar Basin, China

Volcanic reservoirs have been overlooked for hydrocarbon exploration for a long time. Carboniferous volcanic rocks of the Zhongguai paleouplift contain proven reserves of [Formula: see text]. We have investigated the volcanic reservoirs integrating cores, well, and seismic data, and the proposed volcanic reservoir distribution is controlled by the weathering function, fractures, and lithology. The weathering process makes the originally tight igneous rocks become good-quality reservoirs, and fractures play an important role in connecting different types of pores and act as reservoir space. Isolated and ineffective pores become effective ones due to connection among fractures. Only volcanic breccia can be good-quality reservoirs without any weathering function. The nonlinear chaos inversion controlled by weathered layers shows that the good-quality reservoirs are distributed in the top of the weathering crust and the structural high. Furthermore, fluid-detection attributes and background information prove that oil and gas are distributed along the paleostructural high. The objectives of this study were to (1) describe the characteristics of volcanic reservoirs and determine the controlled rules for reservoir distribution, (2) characterize the distribution of reservoirs and hydrocarbon, and (3) propose an effective workflow for hydrocarbon exploration in volcanic rocks combining geologic and geophysical methods.

Reservoir characteristics and control factors of Carboniferous volcanic gas reservoirs in the Dixi area of Junggar Basin, China

Field outcrop observation, drilling core description, thin-section analysis, SEM analysis, and geochemistry, indicate that Dixi area of Carboniferous volcanic rock gas reservoir belongs to the volcanic rock oil reservoir of the authigenic gas reservoir. The source rocks make contact with volcanic rock reservoir directly or by fault, and having the characteristics of near source accumulation. The volcanic rock reservoir rocks mainly consist of acidic rhyolite and dacite, intermediate andesite, basic basalt and volcanic breccia: (1) Acidic rhyolite and dacite reservoirs are developed in the middle-lower part of the structure, have suffered strong denudation effect, and the secondary pores have formed in the weathering and tectonic burial stages, but primary pores are not developed within the early diagenesis stage. Average porosity is only at 8%, and the maximum porosity is at 13.5%, with oil and gas accumulation showing poor performance. (2) Intermediate andesite and basic basalt reservoirs are mainly distributed near the crater, which resembles the size of and suggests a volcanic eruption. Primary pores are formed in the early diagenetic stage, secondary pores developed in weathering and erosion transformation stage, and secondary fractures formed in the tectonic burial stage. The average porosity is at 9.2%, and the maximum porosity is at 21.9%: it is of the high-quality reservoir types in Dixi area. (3) The volcanic breccia reservoir has the same diagenetic features with sedimentary rocks, but also has the same mineral composition with volcanic rock; rigid components can keep the primary porosity without being affected by compaction during the burial process. At the same time, the brittleness of volcanic breccia reservoir makes it easily fracture under the stress; internal fracture was developmental. Volcanic breccia developed in the structural high part and suffered a long-term leaching effect. The original pore-fracture combination also made volcanic breccia reservoir more easily leached by fresh water or groundwater, leading to secondary erosion pores. Volcanic rock weathering obviously has control on reservoir properties, and while the thickness of the weathering crust is 200–300 m, the properties of volcanic rock reservoir are the best. This is attributed mainly to the period during and after the volcano eruption, in which tectonism made the brittle volcanic rock develop a large number of fractures and micro cracks. This has led to the increased permeability of volcanic rock reservoir, the weathering and leaching effect of volcanic rock diagenetic late phase (which also formed lots of secondary pores), and greatly improved reservoir conditions. The overlying Permian Wutonggou formation mudstone provided high-quality cap rock for oil and gas accumulation.

Characteristics and petroleum origin of the Carboniferous volcanic rock reservoirs in the Shixi Bulge of Junggar Basin, western China

Shixi Bulge of the central Junggar Basin in western China is a unique region that provides insight into the geological and geochemical characteristics of large-scale petroleum reservoirs in volcanic rocks of the western Central Asian Orogenic Belt. Carboniferous volcanic rocks in the Shixi Bulge mainly consist of striped lava and agglomerate, as well as breccia lava and tight tuff. Volcanic rocks differ in porosity and permeability. Striped lava exhibits the highest porosity (average: 14.2%) but the lowest permeability (average: 0.67 × 10−15 m) among the rock types. Primary gas pores are widely developed and mostly filled. Secondary dissolution pores and fractures are two major reservoir storage spaces. Capillary pressure curves suggest the existence of four pore structure types of reservoir rocks. Several factors, namely, lithology, pore structure, and various diagenesis, govern the physical properties of volcanic rocks. The oil is characterized by a high concentration of tricyclic terpane, a terpane distribution of C23 < C21 > C20, and sterane distributions of C27 < C28 < C29 and C27 > C28 < C29. Oil and gas geochemistry revealed that the oil is a mixture derived primarily from P2w source rock and secondarily from P1j source rock in the sag west of Pen-1 Well. The gases are likely gas mixtures of humic and sapropelic organic origins, with the sapropelic gas type dominant in the mixture. The gas mixture is most likely cracked from kerogen rather than oils. The Carboniferous volcanic reservoirs in Shixi Bulge share some unique characteristics that may provide useful insights into the various roles of different volcanic reservoir types in old volcanic provinces. The presence of these reservoirs will undoubtedly encourage future petroleum exploration in volcanic rocks up to the deep parts of sedimentary basins.

Fluid-rock interactions in a geothermal Rotliegend/Permo-Carboniferous reservoir (North German Basin)

Comprehensive data on the chemical composition of reservoir rocks and geothermal brines from the geothermal well doublet Groβ Schönebeck (North German Basin) drilled into a Rotliegend sedimentary and Permo-Carboniferous volcanic rock reservoir were sampled over the past years. They were characterized with respect to their major and minor elemental composition including various isotope ratios. The study considered the impact of drilling and reservoir operations on fluid composition and aimed at determining fluid–rock interactions to gain information on fluid origin and hydraulic pathways.The highly saline fluids (up to 265 g/L TDS) show δ18O and δD of water (2.7–5.6 and −3.1–15, respectively) as well as δ34S of sulfate (3.6–5), and 87Sr/86Sr ratios (0.715–0.716) that resemble Rotliegend brines from an area located around 200 km in the west (the Altmark). Halogen ratios indicated that brines developed predominantly by evaporation of meteoric water (primary brine) together with halite dissolution brine (secondary brine). Indication for mixing with Zechstein brine or with younger meteoric water was not found.No geochemical distinction was possible between fluids deriving from different rock formations (dacites or sedimentary rocks, respectively). This is due to the evolution of the sediments from the effusive rocks resulting in a similar mineralogical and chemical composition and due to a hydraulic connectivity between the two types of rock. This connection existed probably already before reservoir stimulation as indicated by a set of faults identified in the area that could connect the Rotliegend formation with both, the volcanic rocks and the lower units of the Zechstein. Additional geochemical indication for a hydraulic connectivity is given by (1) the very high heavy metal contents (mainly Cu and Pb) in fluids and scaling that derive from the volcanic rocks and were that were also found in increased amounts up at the Zechstein border (Kupferschiefer formation). (2) The 87Sr/86Sr isotope ratios of fluid samples correspond to the ratios determined for the sedimentary rocks indicating that initially the fluids developed in the sedimentary rocks and circulated later, when faults structures were created by tectonic events into the volcanic rocks.

对五八区佳木河组沉积特征和储层特征的整体认识

准噶尔盆地西北缘五八区佳木河组地层厚度较大，火山岩和碎屑岩共存。研究区发育有5个相，分别是冲积扇相、扇三角洲相、喷溢相、爆发相和再搬运火山碎屑岩相。佳木河组一段发育火山岩相和扇三角洲相以及冲积扇的扇中亚相，而火山岩分布范围广，且多岩断层分布。佳木河组一段物性较好，I、II类储层较多，且多发育在火山相中，而碎屑岩多为III类储层。佳木河组二段和三段以扇三角洲为主，三段的火山岩相比二段发育。佳木河组二段和三段以III类储层为主，同样发育有I、II类储层。佳木河组多为好储层，且试油量较高，因此佳木河组可作为油气勘探开发的重点层位。佳木河组的I、II类储层主要发育在喷溢相的下部亚相和爆发相的热碎屑流亚相，火山岩储层值得重视，重点对裂缝和溶蚀带进行预测。 The stratum of Jiamuhe Formation in northwestern margin of the Junggar basin is very thick, which consists of volcano rock and clastic rock. There are 5 facies in the study area including alluvial fan facies, fan delta facies, effusive facies, eruption facies and retransported volcano clastic facies. The first member of Jiamuhe Formation, in which volcanic rock widely distributes along the fault, develops volcano facies, fan delta facies and middle alluvial fan sub-facies. The physical property of the first member of Jiamuhe Formation is better, which develops I or II class reservoir in the volcano clastic rock facies while the class III reservoir mostly develops in the clastic rocks. The fan delta facies are widely developed in the second member and third member of Jiamuhe Formation, and the volcanics in the third member are much more than the second member. The mainly reservoir type in the second member and third member of Jiamuhe Formation is III class reservoir, while I, II class reservoirs are also developed in it. Jiamuhe Formation is a good reservoir, the oil content is high, and soit can be taken as a key position for oil & gas exploration and development. The I class and II class reservoirs in the Jiamuhe Formation are mainly developed in the lower subfacies of effusive facies and hot detrital flow subfacies of outbreak facies. Volcanic rock reservoir is worth paying attention to and focusing on the prediction of fractures and dissolution zone.

Organofacies and paleoenvironment of lower Carboniferous mudstones (Dishuiquan Formation) in Eastern Junggar, NW China

The sedimentary rocks of the Dishuiquan Formation represent an important potential source for volcanic rock reservoirs and record the transition of the depositional environment from marine to terrestrial during paleo-Junggar oceanic subduction. The source rock potential and paleoenvironment of mudstones from Dishuiquan Formation in Eastern Junggar, were determined by organic petrography, Rock-Eval, molecular and stable carbon (δ13C) analyses. TOC, S2, and hydrogen index (HI) values suggest a fair to good organic richness in mudstone samples from the C-2 well. Moreover, an early mature to mature state for all the samples is inferred based on the Rock-Eval and biomarker parameters. The maceral composition, molecular geochemistry and carbon isotopic results for kerogen reveal that all the mudstone samples are characterized by a mixed organic matter assemblage (Types II–III) with relatively high percentages of terrigenous organic matter. The low to intermediate values of Pr/Ph and the high abundances of β-carotene and gammacerane indicate the presence of a dysoxic, reducing, high-salinity sedimentary environment during the deposition of the Dishuiquan Formation. Numerous parameters derived from the organic geochemical analyses indicate that the terrigenous organic matter increased with decreasing salinity and oxidation in the sedimentary environment. This study concludes that a warm, wet climate provided a continuous fluvial input of terrigenous plant debris and fresh water. The organic geochemical data, combined with the tectonic setting, reveal a restricted, semi-closed marine depositional environment during the deposition of the Dishuiquan Formation in the early Carboniferous.

Petroleum geology of Carboniferous volcanic weathered crust in northern Xinjiang, China

Abstract Previous studies on volcanic rock reservoirs were focused on lithology, lithofacies and fractures. Primary processes may lead to high porosity and permeability, and secondary processes tend to decrease primary porosity. However, this is not the case in northern Xinjiang, where Carboniferous volcanic rocks covered an area of 378×103 km2 dominated by intermediate-basic rocks of low porosity. At the end of the Carboniferous, these rocks were uplifted, underwent denudation and weathering, and then formed a weathered crust. All types of volcanic rocks might form favorable reservoirs after long-term weathering. The reservoir properties of the crust were controlled by weathering degree and fault development. Four types of reservoir porosity developed: dissolutional pore, pore-fracture, fracture and fracture-cave. Dissolutional pores and fractures are the main reservoir spaces. Under the influence of fractures and an enhanced fracture dissolution environment, the volcanic reservoirs have improved physical properties in deeper burial settings. The depth range of effective reservoirs under the unconformity, either close to, or far from fracture zones, is between 1100 m and 550 m, with maximum porosities of 32% and 24%, respectively. Hydrocarbons have accumulated close to the effective source rock zone due to strong heterogeneities of the volcanic reservoir. The overlying Carboniferous mudstone formed effective caprock. The current structural highs and slope zone coincided well with the paleogeomorphology and form traps for hydrocarbons. Faults and fractures control hydrocarbon enrichment. This is contrary to the view that the Carboniferous is simply impermeable basement in this region, and not capable of hydrocarbon generation.

Internal structure and sealing properties of the volcanic fault zones in Xujiaweizi Fault Depression, Songliao Basin, China

Abstract Through outcrop observation of the internal structure of volcanic fault zone and in combination with fault sealing mechanism research and lithology juxtaposition evaluation, this paper analyzes the internal structure and lateral fault sealing of a volcanic fault zone of the Xujiaweizi Fault Depression. The “binary structure” of damage zone and fault core is developed inside the volcanic fault zone. The fault does not have the sealing property basically at the juxtaposition of volcanic rock. Lithologic juxtaposition sealing is formed at the juxtaposition of the volcanic rock reservoir stratum and the overlying conglomerate bed and mudstone bed. By improving the traditional Knipe diagram (single-well triangle diagram), a dual-well triangle map is drawn to indicate the influence of strike-slip fault on the lithology juxtaposition. Modeling is established with the dual-well triangle diagram and in combination with the fault lithology juxtaposition diagram to evaluate the fault sealing property. Research showed that the gas pools in the Xujiaweizi Depression are almost in the upside of faults; in the longitudinal, gas-water contract is almost at the most shallow position of volcanic juxtaposition and the horizontal distribution of gas pools around faults is just like the curve “sine” as the result of the “dolphin effect” of the Xuzhong strike fault.

火山岩储层构造–成因分类探讨

火山岩传统分类强调岩类学内涵，与储集空间联系不紧密，不能满足油气勘探中储层研究的需要。基于火山岩储集空间类型、组合及其成因分析，归纳了6种与储集空间联系最紧密的因素，结合传统岩类学方案和前人认识，建立了油气勘探中火山岩储层分类新方案。 Traditional classifications of volcanic rock emphasize the connotation of petrography and poorly relate to reservoir spaces, which cannot meet the need for reservoir studies with respect to the oil and gas exploration. Based on the analyses of reservoir space types, combinations and genetics of volcanic rock, six factors that are closely related to reservoir spaces are summed up. Combining with the traditional classification schemes and previous knowledge, a new classification scheme of volcanic rock reservoir in oil and gas exploration is set up.

Huoshiling Formation Volcanic Reservoir Control Factors Analysis of Wangfu Fault Depression in Southern Songliao Basin

Wangfu fault depression Huoshiling Formation in southern Songliao Basin volcanic rocks with larger gas potential, but the volcanic reservoir control factors is not clear, the author take Well Wangfu 1 for example, explore the Huoshiling Formation of volcanic rock reservoir control factors. Well Wangfu 1 main lithology is andesite, volcanic breccia and tuff;on the lithofacies is given priority to with the overflow facies, followed by eruption facies, a small amount of volcanic sedimentary facies; denudation, devitrify and tectonism have the significance on improving reserving space; gaps in the tuff to improve large reservoir, it is more obvious that andesite and volcanic breccia improving permeability; volcanic breccia of Well Wangfu 1 is the relatively favorable reservoir space.

Volcanic Rock Diagenesis and Characteristics Analysis of Yingcheng Formation in Yaoyingtai Area

Research on volcanic rock diagenesis have important reference value in volcanic rock secondary pore formation, evolution and reservoir prediction. Using the core data, flakes, imaging logging, geochemicals analysis and lithologies-lithofacies characteristics of Yaoyingtai area in Yingcheng Formation, Changling fault depression, we research on the volcanic rock diagenesis, reservoir space types, characteristics and relationships. The results are shown that: The research area mainly develop volcanic rock mantle thermal liquid alkali metasomatism and other 11 diagenesis types, and base on diagenesis formation mechanism and the effects of the reservoir spaces, which is divided constructive and destructive.

Application of Integrating Seismic Attribute with Simulation in Volcanic Rock Reservoir

The conventional reservoir simulation is only reasonably consistent with history matching. An application will be presented in this paper by integrating seismic data and production data to achieve history matching. It is hard to accurately describe the reservoir and fracture modeling due to lack of fracture logging data in volcanic rock reservoir area of Bin 3. The study found that it has a close relationship between the distribution characteristics of volcanic rock and seismic attributes.The high-value region of coherence cube attribute usually correspond to tight basalts, so it is very like a fracture broken zone. With denser lithology and higher impedance value, the high-angle fractures will be better abundant. Great deals of intensive fracture and comprehensive effect have been simulated through volcanic rock reservoir simulation restricted by seismic data. By improving history matching, the approach also deepens the possible distribution pattern of fracture-developed zone in 3D space. On the basis of that, stable and high production wells have been designed and put forward.

Research Progress on Volcanic Rock Reservoirs Based on Properties of Energy Materials in Songliao Basin

Properties of Energy Materials (oil and gas) is very complex and important. In recent years, in Chinese eastern, western and mid continental basins, multiple rock oil and gas fields are found, such as Songliao Basin, Bohai Bay Basin, Erlian Basin, Tuha Basin, Junggar Basin, Sichuan Basin. Volcanic rock reservoir with its rich oil and gas resources, tremendous development potential, has aroused the domestic and foreign experts and scholars attention, volcanic rock oil and gas exploration theory and technology has been rapid development. In order to understand volcanic rock reservoir from the origin, further exploration target and guide the exploration deployment, the Properties of Energy Materials (oil and gas), main factors affecting of the development and comprehensive evaluation have become the research hot spots and the focus, there are many research techniques and results.

Optimization Proration Research in Volcanic Reservoir in Songnan Gas Field

Volcanic Reservoir in Songnan gas field is now in the early development, the scale of the single well and stable development put forward important requirements, reasonable match is efficient in gas reservoir development of the key. According to the geological conditions of volcanic rock reservoirs special, in the full analysis of the dynamic and static data, and on the basis of preliminary mastered the gas, water relations; And the use of gas production method, the method of curve, economic boundary method and the improvement of horizontal Wells method of the gas line technology reasonable production optimization and argument, high efficient and economical for gas field development.

Geochemistry of coal-measure source rocks and natural gases in deep formations in Songliao Basin, NE China

The natural gases developed in deep volcanic rock reservoirs of the Songliao Basin, NE China are characterized by enriched δ13C value for methane and frequently reversal carbon isotopic distribution pattern. Although many researchers consider such gas type as an abiogenic origin, we believe the natural gases have a biogenic origin mainly except little inorganic gases and the reversal carbon isotopic distribution pattern of gases is caused by mixing of different origin gases.

Petroleum secondary migration and accumulation in the central Junggar Basin, northwest China: Insights from basin modeling

The timing of petroleum generation, migration, and accumulation in the central Junggar Basin has been evaluated using basin modeling technology to decipher the processes of petroleum secondary migration and accumulation in the Jurassic carrier beds during the Yanshan and Himalayan orogenies. During the early Yanshan orogeny (J2–J3), crude oils, sourced mainly from the Permian source rocks, migrated laterally from depocenters to adjacent structural high points. During the late Yanshan orogeny (Cretaceous–Eocene), the hydrocarbon secondary migration pattern changed significantly. Specifically, in the Cretaceous, a large-scale regional second phase of generation and migration occurred in the western part of the central Junggar Basin; in the eastern part of the central Junggar Basin, crude oils emplaced in the depressions migrated mainly to the eastern uplifts. In the early Tertiary, oils in the source kitchens generally began migrating to the north and mixed with the Jurassic-generated hydrocarbons. During the Himalayan orogeny (Neogene–Quaternary), this migration was strengthened continually. The modeled results agree with migration-associated geochemical information of the Jurassic accumulations. Integration of the regional geological setting and some petroleum geology data suggest that the Jurassic tectonic high points and facies-change- and unconformity-associated subtle traps are of crucial importance for current oil exploration. Both overpressured bodies in the Triassic and Permian systems and volcanic rock reservoirs of the Carboniferous basement in the uplifts have important implications for future natural oil and gas exploration. This work should help reduce exploration risk in this region.

Theory on logging interpretation of igneous rocks and its application

Abstract Based on the summary of theories and methods of well logging interpretation for igneous rock at home and abroad, a complete interpretation process of well logging is formed, which includes lithology identification, quantitative matrix porosity calculation, quantitative saturation calculation, and fluid nature identification. This paper presents a theory and an application model of porosity and saturation calculation for heterogeneous and complex reservoirs, and establishes a framework for interpreting complex volcanic rock reservoirs; proposes a new method combining ECS with FMI logging for 3-D lithology identification of igneous rocks. Based on the study of the micro-fracture simulation well, this paper puts forward a practical quantitative calculation method for calculating the fracture porosity of heterogeneous reservoirs. By experimenting with core of whole diameter under high temperature and high pressure, the authors studied the influence of fracture on saturation calculation through numerical simulation, and proposed a new method of quantitative saturation calculation. The results of the Xujiaweizi area in the Daqing Oilfield and the Ludong-Wucaiwan area in the Xinjiang Oilfield show that the theory and the method are correct and effective.

Volcanic rocks as prolific gas reservoir: A case study from the Qingshen gas field in the Songliao Basin, NE China

The Qingshen gas field, with over 100 billion cubic meters (bcms) of proven gas reserves, was discovered recently in the Upper Jurassic–Lower Cretaceous strata of the Songliao Basin, northeastern China. The stratigraphic relationships and gas chemical compositions indicate mixed gas sources, dominantly from the Upper Jurassic–Lower Cretaceous coals and associated dark mudstones underlying the gas reservoirs, with minor contribution from deep inorganic sources. The gas reservoirs consist mainly of volcanic rocks (rhyolite and tuff), with some production also from the conglomerate. Gas charge into these largely volcanic rock reservoirs appears to coincide with the peak gas generation in the deep Upper Jurassic–Lower Cretaceous coal measures. The presence of several thick lacustrine mudstone beds in the Upper Cretaceous strata as regional caprocks and relatively mild structural deformation since the late Cretaceous are among the favorable conditions for the preservation of large volume of natural gases in these relatively deep gas reservoirs. The gas yields are the highest in the paleomorphological highs where fractures and secondary porosity are well developed in the gas reservoirs.

Controls on the quality of Archean metamorphic and Jurassic volcanic reservoir rocks from the Xinglongtai buried hill, western depression of Liaohe basin, China

The common belief among many petroleum geologists that regions of volcanic and metamorphic rocks are generally to be avoided as potential hydrocarbon reservoirs has greatly slowed the research and exploration efforts on hydrocarbon potential in volcanic and metamorphic rocks. However, many hydrocarbon-bearing basins containing volcanic and metamorphic rocks have been found in convergent margin settings and in rift basins. This article describes the reservoir lithofacies and wire-line logs and elucidates the parameters controlling reservoir-quality evolution of Archean metamorphic and Jurassic volcanic rocks from the Xinglongtai buried hill, western depression of the Liaohe basin, China. Four lithofacies (pyroclastics, lavas, volcaniclastics, and volcaniclastic-epiclastics) have been identified in the Jurassic volcanic reservoir rocks, each having different pore types and variable porosity and permeability values and, thus, different reservoir potentials. Pore types in the volcanic rocks include voids, fractures, fissures, weathering cracks, interstices, and vesicles. The volcanic-rock reservoir evolution is primarily controlled by the burial-thermal diagenesis. Plastic deformation and alteration of the biotite during the eogenetic phase led to the considerable loss of primary pores. Destruction of the primary porosity by compaction was limited by the presence of eogenetic carbonate and zeolite cement formation. Dissolution during the deep-burial mesogenetic phase and during near-surface leaching and erosion in the intervening volcanic eruptions enhanced the permeability and increased reservoir quality. The pore types in the Archean metamorphic reservoir include fractures, dissolution voids, and weathering fissures. Where the Jurassic volcanic rocks or the Paleogene source rocks directly cover the weathered zone, the fissures and fractures have remained open, but where the metamorphic rocks are covered by the Mesozoic mudstones, most fissures are filled with mud and iron oxides. Reservoir quality of the Archean metamorphic and Jurassic volcanic rocks is also partly related to the paleogeomorphology of the area. Rocks in the paleohighs and in adjacent transitional areas have enhanced reservoir properties greater than those in paleolows because of more extensive weathering and the development of vugs and fissures.

低浸透性火山岩貯留層に対する水圧破砕法の技術課題

低浸透性火山岩貯留層に対する水圧破砕法の技術課題