Julien Meunier

Reservoir monitoring using permanent sources and vertical receiver antennae The Céré-la-Ronde case study

Arguably, the cheapest and safest place to store gas is inside a reservoir. Over the years, Gaz de France has developed a unique expertise in this field. A brine-filled reservoir is used to store imported gas during summer and pump it out in winter according to market demand. Monitoring bubble expansion, field pressure, and gas saturation is critical to optimize field management and gas recovery. Several seismic monitoring experiments have been carried out over Cere-la-Ronde test site, with varying degrees of success.

Harmonic Noise Reduction Opens the Way For Array Size Reduction In VibroseisT Operations

To compensate for the reduced number of vibrators per shot point required by reductions in group interval and array size, either the recording time per surface unit must be increased or high order simultaneous recording techniques such as the slip sweep technique should be used. Yet these techniques suffer from distortion, which contaminates the data in proportion to the productivity increase generated. A method to significantly reduce this contamination is presented. . Introduction

Seismic Repeatability – Is There a Limit?

The results of a 13-day seismic monitoring experiment are presented. It consists in 2 permanent piezoelectric sources, one cemented in depth and the other attached to a surface concrete pad and 28 sensors, 14 at the surface and 14 cemented below the weath

Continuous High-Resolution Seismic Monitoring of SAGD

We used a pre-existing buried geophone array located on a heavy oil SAGD (Steam-Assisted Gravity Drainage) pilot project in Alberta. This array has been used to evaluate the ability of a new seismic technique based on permanent sources and receivers to provide a fast indicator of steam motion. The high repeatability of this technique enabled observation of the steam’s progression over a period of one month.

V1: Implementation and application of single-vibrator acquisition

In land seismic operations, there is a strong drive to improve both quality and performance to meet the increasing demand for high-density and wide-azimuth recording.

Pseudo-random coded simultaneous vibroseismics

Simultaneous recording is coming back as a center of interest for acquisition teams, for productivity (Rozemond, 1996) or quality improvement (Baeten et al, 2000) or for multi-source monitoring (Meunier et al, 2001). Methods involving phase encoded sweeps are limited, due to harmonics and correlation side lobes. Such problems could be overcome using the ability to submit digital signals offered by new vibrator electronics.

Evaluation and handling of positioning differences in 4D seismic

Introduction In a presentation given earlier this year at the EAGE conference in Stavanger, we concluded that 1-m accuracy was needed to keep 4D noise below the 20-dB limit in the presence of low apparent velocity. We also noticed that, in some severe cases, changes in the arrays themselves could significantly increase 4D noise. It became natural to think of possible ways not only to evaluate but also to compensate for positioning differences.

Analysis of the slip sweep technique

A 2D slip-sweep simulation experiment was recorded in the Mabruk field in Libya. In order to prepare this experiment, a preliminary analysis was conducted using synthetic data. Various types of noise were isolated and the corresponding data contamination analyzed. Signal-tonoise ratio maps were generated for various slip-sweep configurations. The same analyses were conducted on the actual data after slip sweep simulation, correlation and standard processing. Considering a 10 second slip time, the noise added to the data was lower than -20 dB.

Efficient Wave Field Sampling in Vibroseis Operations.

Summary It has been observed on multiple occasions that after full processing, residual organized noise depends on source and receiver line intervals. An explication of this observation is proposed and illustrated by a recent single vibrator experiment in Egypt.

Automatic Quantified Seismic Quality Control in Land Acquisition

Summary Since the beginning of the 90’s, quality control systems have been routinely used on all land acquisition crews. These systems are designed to validate seismic and support data in the field in order to deliver error-free data to the processing centers. This paper illustrates the use of a new type of control. Its aim is to quantify the seismic quality in land field operations in order to help define the best parameters at the beginning of a survey, and compute automatically quantitative attributes and monitor them throughout the acquisition phase. These attributes can be mapped and saved on files for transfer to the processing center to reduce turnaround times. They could also be used, in the future, for appropriate attribute-dependent routines, especially when using preserved amplitude processing.