CN-122017200-A - Downhole core substitution method based on mudstone outcrop of pattern plate

CN122017200ACN 122017200 ACN122017200 ACN 122017200ACN-122017200-A

Abstract

The invention discloses a shale outcrop underground core replacing method based on a drawing plate. The method comprises the following steps of S1, collecting open-air mudstone outcrop and preparing a core, obtaining existing core experimental data, manufacturing a plate according to the existing core experimental data and combining logging sound waves and density, S2, measuring initial density of the mudstone outcrop under normal pressure, carrying out initial burial depth homing and density numerical correction of the exposed core under the plate, S3, calculating rock parameters of a mudstone outcrop homing point under the plate, carrying out overpressure correction of the mudstone outcrop homing point stratum if target stratum has overpressure, and S4, judging whether relevant parameters after the mudstone outcrop core correction meet quality requirements. The method has the beneficial effects that logging, underground rock cores, experiments and a pattern plate are comprehensively utilized, the outcrop of the mudstone at the same layer is reset through the depth correction of the pattern plate, the density, the speed and the mechanical properties of the mudstone at different depths are obtained, and the three-dimensional geomechanical fine modeling of the underground stratum is realized.

Inventors

ZHANG MING
YANG XINHAO
HUO HONGBO
LIN HAI
SUN LIANPO
SONG CHUANG
LI WENBO
CHEN ZHUO
ZHANG YUCHEN
SUN DALIN

Assignees

中海石油(中国)有限公司
中海石油（中国）有限公司天津分公司

Dates

Publication Date: 20260512
Application Date: 20260303

Claims (8)

1. The downhole core substitution method based on the mudstone outcrop of the pattern plate is characterized by comprising the following steps of: S1, acquiring existing core experimental data, and manufacturing a plate according to the existing core experimental data and combining logging sound waves and density; S2, carrying out initial density measurement of the mudstone outcrop under normal pressure, and carrying out initial burial depth homing and density numerical correction of the outcrop core under the plate; s3, calculating rock parameters of the mudstone outcrop return point under the plate, and correcting the stratum overpressure of the mudstone outcrop return point if the target stratum has overpressure; and S4, judging whether the parameters after the mudstone outcrop core is corrected meet the quality requirements.
2. The method for replacing underground rock core with mudstone outcrop based on the pattern of claim 1, wherein in step S1, the existing rock core experimental data comprises lithology, depth, density, rock velocity, uniaxial compressive strength and Young' S modulus, and the pattern comprises a mudstone density-burial depth intersection pattern, a mudstone density-velocity intersection pattern, a burial depth-surrounding pressure intersection pattern, a pressure-mudstone density variation intersection pattern, an overpressure-mudstone density variation intersection pattern and an overpressure-mudstone velocity variation intersection pattern.
3. The method for replacing underground rock core of mudstone outcrop based on pattern plate as set forth in claim 1, wherein in step S2, the initial density of the mudstone outcrop under normal pressure is determined by obtaining the initial density of the outcrop rock through rock electric experiment 。
4. The downhole core replacement method based on mudstone outcrop of the plate as claimed in claim 3, wherein in step S2, the method of initial burial depth homing of the lower outcrop core of the plate is: In the mudstone density-burial depth intersection plate, the initial density of the mudstone outcrop is used For indicating, reading the first homing depth value of the original burial depth of the mudstone outcrop Reading the first homing depth of the mudstone outcrop in the burial depth-confining pressure intersection plate Corresponding confining pressure value Reading the confining pressure value on the pressure-mudstone density variation intersection plate The corresponding mudstone density variation is the first-time density correction value of the mudstone outcrop Corresponding density after first original burial depth correction of mudstone outcrop Reading in the mudstone density-burial depth intersection plate Corresponding depth value Namely the original buried depth homing depth value of the mudstone outcrop 。
5. The method for replacing underground rock core of mudstone outcrop based on the pattern plate according to claim 2, wherein in the step S2, the density value correction method is that the original burial depth of the mudstone outcrop is reset Corresponding stratum confining pressure Reading the confining pressure according to the intersection plate of the pressure and the mudstone density variation Corresponding mudstone outcrop density variation correction quantity value Further utilize = Obtaining the mudstone density under the correction of the original burial depth of the mudstone outcrop 。
6. The downhole core replacement method based on mudstone outcrop of the plate according to claim 5, wherein in the step S3, the rock parameters include poisson 'S ratio, young' S modulus, and rock strength, and the calculation method of the mudstone outcrop-returning point rock parameters under the plate is as follows: Density corrected by mudstone outcrop The original burial depth can be read by the clay rock density-speed intersection plate And obtaining poisson ratio, young modulus and rock strength according to the mudstone density and the mudstone speed.
7. The downhole core replacement method of shale outcrop based on the pattern as claimed in claim 6, wherein in step S3, the shale outcrop return site formation overpressure correction method is: re-correcting the mudstone density under the formation overpressure under the condition of the mudstone overpressure-density variation intersection plate, and reading the mudstone density correction amount by using the formation pressure gradient Density of mudstone outcrop under original burial depth and formation pressure The method comprises the following steps: Wherein, the And correcting the mudstone density under the original burial depth of the mudstone outcrop.
8. The method for replacing the underground rock core of the mudstone outcrop based on the graphic plate as claimed in claim 1, wherein in the step S4, the quality inspection is carried out by utilizing the uniaxial compressive strength of the existing underground rock core experimental result, and when the uniaxial compressive strength of the mudstone outcrop rock core after initial burial homing correction is more than 90% in comparison conformity with the rock core with the same depth, the quality requirement is met.

Description

Downhole core substitution method based on mudstone outcrop of pattern plate Technical Field The invention relates to the technical field of oil and gas drilling engineering, in particular to a shale outcrop underground core substitution method based on a plate. Background In geological research, oil and gas exploration or mineral resource evaluation, a downhole core is an underground rock sample obtained through drilling, the downhole core is a core carrier for directly obtaining underground rock stratum information, and the core data of stratum lithology, physical property, oil and gas content and structural characteristics can be directly analyzed. However, the method is limited by the factors of high drilling cost, high acquisition cost of the underground rock core, limited coring proportion, severe underground rock core preservation condition, difficult coring of partial areas due to technical limitations and the like, and in some cases, the method is difficult to acquire the complete or high-quality underground rock core. At the moment, the outcrop core, namely the natural rock stratum sample exposed on the surface and the rock blocks artificially or naturally exposed in the natural rock section, can be used as important substitutes, and can provide key supplementary information for the underground core research under similar geological conditions through scientific selection and reasonable analysis. The underground core substitution technical method of the outcrop core is relatively few in the present stage, the outcrop core substitution technical method comprises the steps of obtaining the outcrop rock sample through a specific drilling method, analyzing the characteristics of gravel quantity, particle size, sorting coefficient and the like, defining a gravel characteristic coefficient S, comparing the similarity of the underground core and the outcrop core, selecting an outcrop core plunger matched with the physical property of the underground core, and being used for supplementing an indoor experiment, mainly solving the problem that the underground core of a sand stratum is difficult to obtain, being suitable for reservoir research in petroleum and natural gas exploration and development, and the technical characteristics are that the outcrop core is used for preparing a heterogeneous core model by mixing the outcrop core with quartz sand and epoxy resin, simulating the vertical heterogeneity of a reservoir, being used for a physical sediment simulation experiment, realizing the accurate preparation of a plurality of layers of heterogeneous cores by controlling the permeability of adhesives, and being suitable for researching the sediment process and reservoir evolution. However, the conditions are strictly required, and rock elastic properties, related mechanical parameters and the like under the underground conditions cannot be effectively simulated. Aiming at the conditions of lack of underground mudstone cores and insufficient existing core substitution table technology in oil-gas field development, logging, underground cores, experiments and plates are comprehensively utilized, the mudstone outages at the same layer are subjected to depth correction homing through the plates, the density, speed and mechanical properties of the mudstones at different depths are obtained, and the three-dimensional geomechanical fine modeling of the underground stratum is realized. Disclosure of Invention The invention aims to provide a downhole core replacement method for mudstone outcrop based on a plate, which comprehensively utilizes logging, downhole core, experiments and the plate, and the mudstone outcrop at the same layer is subjected to depth correction homing through the plate to obtain density, speed and mechanical properties of the mudstone at different depths, so as to realize three-dimensional geomechanical fine modeling of a subterranean stratum. In order to achieve the above purpose, the invention adopts the following technical scheme that the method comprises the following steps: S1, acquiring existing core experimental data, and manufacturing a plate according to the existing core experimental data and combining logging sound waves and density; S2, carrying out initial density measurement of the mudstone outcrop under normal pressure, and carrying out initial burial depth homing and density numerical correction of the outcrop core under the plate; s3, calculating rock parameters of the mudstone outcrop return point under the plate, and correcting the stratum overpressure of the mudstone outcrop return point if the target stratum has overpressure; and S4, judging whether the parameters after the mudstone outcrop core is corrected meet the quality requirements. Preferably, in step S1, the existing core experimental data comprises lithology, depth, density, rock velocity, uniaxial compressive strength and Young' S modulus, and the plates comprise mudstone density-burial depth intersection plate,