CN-121993147-A - Method for judging inter-well connectivity based on microbial genome DNA analysis

CN121993147ACN 121993147 ACN121993147 ACN 121993147ACN-121993147-A

Abstract

The invention belongs to the technical field of dynamic monitoring of oil extraction engineering, and particularly relates to a method for judging inter-well connectivity based on microbial genome DNA analysis. The method comprises the steps of obtaining liquid samples of a production well and a water injection well and rock debris samples of a new well in the same area and stratum with the production well, carrying out microbial genome DNA analysis on the obtained samples to obtain dominant strain compositions of the production well, the water injection well and the new well, comparing the number of dominant strains shared by the production well and the water injection well and the number of dominant strains shared by the production well and the new well, and judging connectivity of the production well and the water injection well according to a comparison result. The invention provides a novel method for judging the connectivity among wells, which can effectively solve the problems that the water-filling development oil reservoir is influenced by factors such as dominant channels, natural cracks, water-filling dynamic cracks and the like, the water-filling direction of an oil production well is complex, and the judgment is difficult to be clear.

Inventors

LU HONGJUN
WANG ZHUO
WANG FEI
YAN CHANGHAO
BAI XIAOHU
LI XIANGPING
DONG QI
Xue Chunqi
LIU JIANSHENG
WANG CHEN

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260508
Application Date: 20241101

Claims (10)

1. A method for determining interwell connectivity based on microbial genomic DNA analysis, the method comprising: Obtaining liquid samples of a production well and a water injection well, and a newly drilled rock debris sample in the same area and stratum with the production well; Performing microbial genome DNA analysis on the obtained sample to obtain dominant strain composition of a production well, a water injection well and a new well; and comparing the number of dominant strains shared by the oil production well and the water injection well and the number of dominant strains shared by the oil production well and the new well, and judging connectivity of the oil production well and the water injection well according to a comparison result.
2. The method for judging the connectivity between wells according to claim 1, wherein the dominant strain is a strain with a strain concentration of not less than 10%.
3. The method for judging well-to-well connectivity according to claim 1, wherein the oil well is judged to be in communication with the water injection well when the number of dominant species in common to the oil well and the water injection well is greater than or equal to the number of dominant species in common to the oil well and the new well, and the oil well is judged to be not in communication with the water injection well when the number of dominant species in common to the oil well and the water injection well is less than the number of dominant species in common to the oil well and the new well.
4. The method for judging the connectivity between wells according to claim 1, wherein rock fragments of different depths of a new well are collected, gradient sampling is carried out according to the mode that the collection amount is increased from shallow to deep, and the rock fragments are taken as the rock fragments of the new well after mixing.
5. The method of claim 4, further comprising pulverizing the fresh drill cuttings sample, mixing with sterile physiological saline to form a suspension, and performing a microbial genomic DNA analysis on the suspension.
6. The method of claim 1, wherein the liquid samples of the oil recovery well or the water injection well are collected in multiple steps and mixed to be used as the liquid samples of the oil recovery well or the water injection well.
7. The method for judging the connectivity between wells according to claim 6, wherein liquid samples of the oil recovery well or the water injection well are collected for more than 3 months continuously, samples are taken every 2-4 weeks for 1-2 months, and samples are taken every 1 month after the third month.
8. The method for determining well connectivity according to claim 1, wherein the microbial genome DNA analysis comprises extracting total DNA of the liquid sample or the rock debris sample, performing PCR amplification by using the total DNA as a template, sequencing the DNA of the sample, and analyzing the type of the assayed microbial species and the concentration thereof.
9. The method of claim 8, wherein the PCR amplification system comprises primers, dNTPs, taq DNA polymerase, template DNA, and a PCR reaction buffer.
10. The method of claim 8, wherein the PCR amplification procedure comprises denaturation at 92 ℃ for 30s, annealing at 55 ℃ for 20s, and then extension at 70 ℃ for 30s, and cycling 25-35 times.

Description

Method for judging inter-well connectivity based on microbial genome DNA analysis Technical Field The invention belongs to the technical field of dynamic monitoring of oil extraction engineering, and particularly relates to a method for judging inter-well connectivity based on microbial genome DNA analysis. Background With the continuous deep development of oil fields, partial extremely low permeability and ultralow permeability oil reservoirs enter a high water content period (65.4%), a high extraction degree (17.0%), water flooding contradiction is aggravated, water content rises rapidly (1.9%), the water content is influenced by factors such as sand body dominant channels, natural cracks, water injection dynamic cracks and the like, the water inlet direction of an oil well is complex, the daily oil increment of a single well by conventional water shutoff and profile control measures is less than 0.8t/d, the water content rising rate is more than 10%, the water inlet direction needs to be marked urgently, the communication relation among oil-water wells is accurately judged, the measure with strong pertinence is formulated, and the water control and oil increment are realized. At present, aiming at the communication relation among oil-water wells, the conventional solution is to shut down the water injection well or reduce the water injection quantity and observe the dynamic response characteristic of the water injection well, but the method has long period and more affected factors, and is difficult to describe the complicated water injection direction. The other method is that a specific type of tracer is added into the injected water of the water injection well, an oil water sample produced by the oil well is taken periodically, the type and the content of the tracer are analyzed by assay, the tracer is compared with the injected tracer, whether water is penetrated is judged by detecting the tracer, and the water penetrating communication degree is judged by the concentration of the tracer. However, the tracer belongs to invasive work, is easy to pollute a reservoir, damages the background concentration of the reservoir, generates irreversible damage to the reservoir, and meanwhile, has higher cost and cannot realize real-time monitoring. Disclosure of Invention In view of the defects of the prior art, the invention provides a method for judging the connectivity among wells based on the microbial genome DNA analysis, which can effectively solve the problems that water injection development reservoirs are influenced by factors such as dominant channels, natural cracks, water injection dynamic cracks and the like, the water-gathering direction of oil extraction wells is complex, and the judgment is difficult to be clear. The invention adopts the following technical scheme: the invention provides a method for judging the connectivity between wells based on microbial genome DNA analysis, which comprises the following steps: Obtaining liquid samples of a production well and a water injection well, and a newly drilled rock debris sample in the same area and stratum with the production well; Performing microbial genome DNA analysis on the obtained sample to obtain dominant strain composition of a production well, a water injection well and a new well; and comparing the number of dominant strains shared by the oil production well and the water injection well and the number of dominant strains shared by the oil production well and the new well, and judging connectivity of the oil production well and the water injection well according to a comparison result. In some embodiments, the dominant species is a species having a species concentration of greater than or equal to 10%. The method comprises the steps of detecting a plurality of dominant microorganism strains with the concentration of more than or equal to 10% of a rock debris sample of a newly drilled stratum to serve as primary marker microorganism strains of the stratum, determining the layer marker microorganism flora and the concentration as a primary microorganism strain comparison template of an oil reservoir, detecting a plurality of dominant microorganism strains with the concentration of more than or equal to 10% of a water injection well injected water sample to serve as water injection well marker microorganism strains, and determining the water injection marker microorganism strains and the concentration as a surface water microorganism strain comparison template. In some embodiments, the production well is determined to be in communication with the water injection well when the number of dominant species in common with the production well and the water injection well is greater than or equal to the number of dominant species in common with the production well and the new well, and the production well is determined to be not in communication with the water injection well when the number of dominant species in common with the production well and