Method for predicting high-quality reservoir development zone of clastic rock buried hill

Abstract

The invention relates to the field of prediction of clastic rock buried hill reservoirs, in particular to a method for predicting a high-quality reservoir development zone of a clastic rock buried hill. A method for predicting a high-quality reservoir development zone of a clastic rock buried hill comprises the following steps: step 1, material source condition analysis: finding out the material source of each sedimentary area, dividing the material source type, and determining the relationship between each material source and the reservoir physical property; 2, sedimentary facies condition analysis, wherein sedimentary facies plane distribution of a research area is found out, and the relation between various terrestrial clastic rock sedimentary facies and reservoir physical properties is determined; 3, diagenesis condition analysis: finding out diagenesis types of the research area, determining the relationship between various diagenesis and reservoir physical properties, dividing constructive diagenesis and destructive diagenesis, and determining high-quality reservoir control factors; and 4, favorable zone prediction: comprehensively predicting a high-quality reservoir development zone according to the source, the sedimentary facies and the diagenesis.

Description

Technical Field

[0001] The invention relates to the field of oil and gas exploration and development, and in particular to a method for predicting a high-quality reservoir development zone in a clastic rock buried hill. Background Art

[0002] Clastic buried hills often have rich oil and gas resources and are important successor strata in conventional oil and gas basins. Limited by provenance, sedimentation, and tectonic action, it is difficult to predict high-quality reservoirs in clastic buried hills. Currently, most methods use experimental analysis and test data such as cores, cuttings, thin sections, X-ray diffraction, mercury injection, and scanning electron microscopy to analyze the characteristics and development control factors of high-quality reservoirs in combination with the petrological characteristics, main diagenesis, and reservoir space characteristics of the target layer clastic reservoirs. Exploration has confirmed that many major breakthroughs have been made in the exploration of clastic oil and gas in buried hills, and many wells have obtained high-yield oil and gas flows, showing great potential for oil and gas exploration.

[0003] At present, there are some technologies related to the prediction of buried hill reservoirs, such as core observation, thin section identification, fluid inclusion analysis, carbon and oxygen isotope composition analysis, etc., combined with structural and burial evolution history, to conduct systematic analysis. For example, the diagenetic evolution process, reservoir genesis and development model of the Upper Paleozoic Permian clastic reservoir in the Bohai Bay Basin, and the influence of abnormally high pressure on reservoir development can be detected by acoustic waves.

[0004] The accuracy of sedimentary facies research at this stage cannot meet the current exploration needs, and there is no clear understanding of sedimentary systems and river types. It is difficult to predict high-quality reservoirs, and most of them are based on single technical means such as geophysics and drilling analysis. For clastic rock buried hill formations with great burial depth and little drilling data, prediction is difficult and has low accuracy. Summary of the invention

[0005] The purpose of the present invention is to provide a method for predicting the development zone of high-quality reservoirs in clastic buried hills, so as to solve the problem that it is difficult to predict the clastic buried hill strata with great burial depth and little drilling data.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for predicting the development zone of high-quality reservoirs in clastic buried hills comprises the following steps: Step 1, source condition analysis: identify the source of each sedimentary area, classify the source types, and clarify the relationship between each source and reservoir properties; Step 2, sedimentary facies condition analysis: find out the planar distribution of sedimentary facies in the study area and clarify the relationship between various types of terrigenous clastic rock sedimentary facies and reservoir physical properties; Step 3, diagenesis condition analysis: identify the diagenesis types in the study area, clarify the relationship between various diagenesis and reservoir properties, divide constructive diagenesis and destructive diagenesis, and clarify the control factors of high-quality reservoirs; Step 4, prediction of favorable zones: Comprehensively predict the zones where high-quality reservoirs will develop, taking into account provenance, sedimentary facies, and diagenesis.

[0007] A further technical solution is that the provenance type in step 1 includes the lithology of the provenance, the distance of the provenance, and the size of the provenance.

[0008] A further technical solution is that the terrigenous clastic rock sedimentary phase in step 2 includes foothill-alluvial phase, river phase, lake phase, delta phase and marine-continental transition phase.

[0009] A further technical solution is that the types of diagenesis in step 3 include compaction, pressure solution, cementation and replacement.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The present invention conducts provenance analysis, sedimentary phase analysis and diagenetic condition analysis on the study area, that is, comprehensively predicts the high-quality reservoir development zone, that is, determines the sediment provenance location and properties and sediment provenance sources, and even the sedimentary structural evolution process of the entire basin through various methods, clarifies the relationship between various provenances and reservoir properties, and through sedimentary phase condition analysis, finds out the sedimentary phase plane distribution in the study area, clarifies the relationship between various phase belts and reservoir properties, and through diagenetic condition analysis, finds out the diagenesis type in the study area, clarifies the relationship between various diagenesis and reservoir properties, divides constructive diagenesis and destructive diagenesis, and clarifies the control factors of high-quality reservoirs. Finally, the provenance, sedimentary phase, and diagenesis are comprehensively predicted to comprehensively predict the high-quality reservoir development zone. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a step module diagram of the present invention. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0013] Figure 1 This is an embodiment of the present invention.

[0014] Example 1 A method for predicting the development zone of high-quality reservoirs in clastic buried hills comprises the following steps: Step 1, source condition analysis: identify the source of each sedimentary area, classify the source types, and clarify the relationship between each source and reservoir properties; Step 2, sedimentary facies condition analysis: find out the planar distribution of sedimentary facies in the study area and clarify the relationship between various types of terrigenous clastic rock sedimentary facies and reservoir physical properties; Step 3, diagenesis condition analysis: identify the diagenesis types in the study area, clarify the relationship between various diagenesis and reservoir properties, divide constructive diagenesis and destructive diagenesis, and clarify the control factors of high-quality reservoirs; Step 4, prediction of favorable zones: Comprehensively predict the zones where high-quality reservoirs will develop, taking into account provenance, sedimentary facies, and diagenesis.

[0015] Example 2 Based on Example 1, the provenance type in step 1 includes the lithology of the provenance, the distance of the provenance, and the size of the provenance.

[0016] Example 3 Based on Example 2, the terrigenous clastic rock sedimentary phases in step 2 include foothill-alluvial phase, river phase, lake phase, delta phase and marine-continental transition phase.

[0017] Furthermore, the foothill-diluvial phase is composed of large and small alluvial fans and the slope deposits and sedimentary deposits filling them. Among them, the sandstone and conglomerate of the middle fan subphase of the alluvial fan phase has moderate grain size, slightly better sorting, loose cementation, good porosity and permeability, and with the development of faults, it can serve as a good reservoir for storing oil and gas.

[0018] Furthermore, the lithology of river sand bodies in the fluvial phase changes rapidly. Vertically, the oil storage properties of the side beach or center beach sandstone in the lower riverbed subphase of the fluvial sedimentary cycle are the best, which gradually deteriorate upwards. Laterally, the oil storage properties are good in the lens body and deteriorate on both sides.

[0019] Furthermore, the lake phase often has good conditions for oil and gas generation and storage. With the uplift and contraction of the lake basin and the supply of exogenous debris, oil-bearing sand bodies such as delta sand bodies, deep-water turbidite fan sand bodies, and shallow lake beach and bar sand bodies are gradually formed. The grain size changes from coarse to fine from the shore to the center of the lake. The rock types are mainly claystone and siltstone, and the sandstone cement is mainly mud and calcareous, with good sorting and rounding. If the lake bottom terrain is gentle, sheet-like sandy shoals or local sandy accumulation and thickened sandbar deposits can develop. They have a wide distribution range and moderate overall grain size, and can serve as good reservoirs.

[0020] Furthermore, the delta front subfacies in the delta facies is distributed with estuarine sand bars, distal sand bars and sheet sand bodies, with strong hydrodynamic effects, pure sand quality and good sorting. In addition, it is closely adjacent to the pro-delta subfacies that is conducive to oil generation, and is a phase belt with favorable reservoir conditions. During the transgression process, the transgressive sand layers of the destruction phase formed also have good reservoir conditions. At the same time, due to the large differences in the properties of delta sediments, under the condition of uneven pressure, salt dome structures can be formed as plastic and easy-to-flow sedimentary bodies, which are good places for oil and gas accumulation.

[0021] Furthermore, in the marine-continental transition phase, different types of sand bodies are developed in the barrier islands, tidal flats, and estuary bay phases. The sandy debris has moderate particle size, good sorting, and uniform lithology. It is laterally adjacent to favorable oil-generating phases such as lagoons and shallow seas, and has favorable conditions for oil and gas enrichment.

[0022] Example 4 Based on Example 3, the diagenesis types in step 3 include compaction, pressure solution, cementation and replacement.

[0023] Furthermore, the compaction effect is affected by the composition, particle size, shape, roundness, sphericity, and sorting of rock particles. For example, a high quartz content makes it difficult to compact during burial. The better the roundness and sorting of the particles, the denser the original sediment filling. However, poor sorting, mixed sizes, and high matrix content also reduce the primary porosity. External factors unrelated to sediments, such as early rapid burial depth, weak cementation or strong dissolution, and the absence of abnormally high pressure, enhance the compaction effect, thereby reducing porosity.

[0024] Furthermore, during pressure solution, if there is a water film on the surface of the quartz particles, especially if there is a clay film between the particles, it can promote the preferential dissolution of the contact between the quartz particles and the diffusion of dissolved substances, the solubility of the contact between the particles increases, lattice deformation and dissolution occur, and the morphology of the compressed part of the particles evolves from point contact to line contact, concave-convex contact and suture contact. Pressure solution provides a large amount of silicon oxide for siliceous cement, which is the main factor for the secondary growth of minerals such as quartz and feldspar and the interpenetration and contact between particles.

[0025] Furthermore, cementation is mainly calcareous, siliceous, ferruginous, sulfate and argillaceous, which plays an important role in transforming sediments into sedimentary rocks and is one of the main reasons for the reduction of porosity and permeability in sedimentary layers. The type of cement is related to the composition of sandstone particles. Most quartz sandstones are cemented by siliceous and carbonates, while lithic sandstones, graywackes and volcaniclastic sandstones are mainly composed of altered matrix and chemical precipitates. Clay minerals are important filling materials in sandstones, which are divided into authigenic and allogeneic. Clay cements change with burial depth. Authigenic clay minerals play a role in reducing the pore space of sandstones. For example, in the process of feldspar kaolinization, potassium ions and silica are removed, and the volume is reduced, so a certain amount of pore space is generated. The damage of authigenic clay minerals to the permeability of sandstone is far greater than the damage to porosity. Illite, chlorite, montmorillonite and illite-montmorillonite mixed clay are mostly produced in the form of particle coatings and pore linings, which are easy to block the pore throats of sandstones and have a significant destructive effect on the permeability of sandstones. Iron oxide and sulfate cements also often appear in some sandstone types. Under the premise of a large amount of cement precipitated in the pores, the saturated fluid is continuously replenished. As the precipitation proceeds, the pore space decreases, the permeability decreases, and the rate of mineral precipitation gradually slows down. At the same time, the cementation of fine-grained sandstone is faster and stronger than that of coarse-grained sandstone. As the cementation proceeds, the material precipitation rate generally decreases exponentially.

[0026] Furthermore, metasomatism refers to the phenomenon that one mineral replaces another mineral. The metasomatizing mineral can replace the edge of the particle. When the metasomatism is thorough, the replaced mineral trace can completely disappear, and the rock structure also changes. At the same time, the porosity and permeability of the rock also change accordingly. Common metasomatisms include silica metasomatism with calcite, calcite metasomatism with feldspar, calcite metasomatism with clay minerals, clay mineral metasomatism with feldspar, and clay minerals metasomatism with each other. Among them, in the case of clay mineral metasomatism with feldspar, plagioclase is buried at a deeper depth and may come into contact with acidic pore water produced from organic-rich mud layers, resulting in kaolinization, which generally occurs along the cleavage plane first, which is of great significance to the formation of secondary pores in clastic rocks.

[0027] Although the present invention is described herein with reference to a number of illustrative embodiments of the present invention, it will be appreciated that those skilled in the art may devise many other modifications and implementations that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the drawings and claims disclosed herein, a variety of variations and modifications may be made to the components and / or layout of the subject combination layout. In addition to the variations and modifications made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A method for predicting the development zone of high-quality reservoirs in clastic buried hills, characterized by: The following steps are involved: Step 1, source condition analysis: identify the source of each sedimentary area, classify the source types, and clarify the relationship between each source and reservoir properties; Step 2, sedimentary facies condition analysis: find out the planar distribution of sedimentary facies in the study area and clarify the relationship between various types of terrigenous clastic rock sedimentary facies and reservoir physical properties; Step 3, diagenesis condition analysis: identify the diagenesis types in the study area, clarify the relationship between various diagenesis and reservoir properties, divide constructive diagenesis and destructive diagenesis, and clarify the control factors of high-quality reservoirs; Step 4, prediction of favorable zones: Comprehensively predict the zones where high-quality reservoirs will develop, taking into account provenance, sedimentary facies, and diagenesis.

2. The method for predicting the development zone of high-quality reservoir in clastic buried hill according to claim 1, characterized in that: The provenance type in step 1 includes the lithology of the provenance, the distance of the provenance, and the size of the provenance.

3. The method for predicting the development zone of high-quality reservoir in clastic buried hill according to claim 1, characterized in that: The terrigenous clastic rock sedimentary phases in step 2 include foothill-alluvial phase, fluvial phase, lacustrine phase, delta phase and marine-continental transition phase.

4. The method for predicting the development zone of high-quality reservoir in clastic buried hill according to claim 1, characterized in that: The types of diagenesis in step 3 include compaction, pressure solution, cementation and replacement.

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