Crosswell seismic imaging for deep gas reservoir characterization

Abstract

A gas discovery in the Shengping area of the Daqing Oilfield in China was made recently in a large-scale volcanic depositional environment. Because gas in the heterogeneities of formations broken by tectonic activity and localized volcanic eruptions is not common, researchers sought a more detailed reservoir characterization before developing the field. Crosswell seismic data were used to augment existing 3D surface seismic, log, and core data. This provided data at five times the resolution of the surface seismic data to bridge the gap in resolution between surface seismic and well data. Crosswell seismic data were acquired in two wells, 832 m apart, and processed to provide images of reflectivity, velocity, and formation properties from sections produced by amplitude-versus-angle ͑AVA͒ inversion. The state of the art in crosswell seismic is summarized briefly, reviewing progress in data acquisition and data processing over several decades of crosswell technology development. A detailed description of the data acquisition and data processing applied to the data from the Shengping area is also given. An integrated interpretation of the crosswell images with the surface seismic and log data was used to produce a more detailed geologic model. The enhanced geologic model is being used to plan strategic development of the reservoir and to evaluate possible infill well locations. REVIEW OF THE STATE OF THE ART IN CROSSWELL SEISMIC Crosswell seismic technology has been under development since the early 1980s with many research groups inside major E & P companies involved in early experiments ͑Lines et al., 1993͒. Initially re

Controlling factors of acoustic properties in continental carbonates: Implications for high-resolution seismic imaging

“…Such method aims to image inter-well areas using high frequency acquisitions (between 100 and 2000 Hz), resulting in the imaging of reflectors representing meter-scale geological contrasts which bridge the gap between sonic log measurements and conventional seismic (e.g. Harris et al, 1995;Leiceaga et al, 2015;Yu et al, 2008). For instance, Parra et al (2003) used a combination of nuclear magnetic resonance, sonic and density well logs with inverted impedance section based on crosswell seismic for characterizing the geometry of heterogeneous vuggy carbonates.…”

Controlling potential far‐field brine leakage from CO2 storage formations using deep extraction wells: Numerical and experimental testing

“…These findings suggest that the extraction well locations can be determined prior to CO 2 injection using high‐resolution data on storage zone heterogeneity collected during site investigation. Such high‐resolution data can be obtained by applying techniques like cross‐well seismic imaging between the injection and monitoring wells before operation 114,115 . However, the extraction rates can be initially estimated using the available data prior to CO 2 injection, but such rates would need to be revisited and adjusted based on the leakage pathways’ permeabilities.…”

Crosswell seismic applications for improved reservoir understanding

“…Other crosswell seismic applications start with the integration of rock physics and then inverting the crosswell data from interface properties to layer properties such as acoustic impedance, V P /V S , or Poisson's ratio and density (Yu et al, 2008). The key steps in the process are well calibrations, wavelet extraction, prior model building, and prestack inversion.…”