Seismic Soundoff: Exploring land seismic case studies

In this episode, Öz Yilmaz discusses his latest book, Land Seismic Case Studies for Near-Surface Modeling and Subsurface Imaging. Written for practicing geophysicists, the book is the culmination of land seismic data acquisition and processing projects conducted by Yilmaz over the last two decades. His expertise and experience are highlighted in detail in this revealing and essential conversation. Hear the full episode at https://seg.org/podcast/post/12564 .

Innovation and Integration: Exploration History, ExxonMobil, and the Guyana-Suriname Basin

Exploration in the Guyana-Suriname Basin has been a decades-long endeavor, including technical challenges and a lengthy history of drilling with no offshore success prior to the Liza discovery. The 1929 New Nickerie well was the first onshore well in Suriname, and was followed by 30 years of dry holes before the heavy-oil Tambaredjo field was discovered in the 1960s. In the 1990s, nearly 40 years after the Tambaredjo discovery, ExxonMobil utilized the 1970s-vintage, poor-to moderate-quality, 2D seismic and gravity data available to create a series of hand-drawn, level-of-maturity (LOM) source and environments-of-deposition (EOD) maps over the basin to move their exploration efforts forward. This work established the genetic fundamentals necessary for understanding the hydrocarbon system and led to negotiation for and capture of the Stabroek Block in 1999. The Liza-1 success in 2015 spurred extensive activity in the Basin by ExxonMobil and the Stabroek Block co-venturers, Hess Guyana Exploration Limited and CNOOC Petroleum Guyana Limited (Austin et al. 2021). The collection of extensive state-of-the art seismic data has been leveraged to enable successful exploration of multiple play types across the Guyana-Suriname Basin. Further data collection, including over 2 km of conventional core and additional seismic data acquisition and processing, has enabled ExxonMobil to adopt interpretation techniques that are applied across the entire basin to characterize and understand the subsurface better. From initial hand-drawn maps to the use of advanced technology today, ExxonMobil's work in the Guyana-Suriname Basin has relied on integration of geologic and geophysical understanding as well as the ability to leverage new technology to continue a successful exploration program with 8 billion barrels discovered to date.

Wireless Geophone Networks for Land Seismic Data Acquisition: A Survey, Tutorial and Performance Evaluation

Seismic data acquisition in oil and gas exploration employs a large-scale network of geophone sensors deployed in thousands across a survey field. A central control unit acquires and processes measured data from geophones to come up with an image of the earth’s subterranean structure to locate oil and gas traps. Conventional seismic acquisition systems rely on cables to connect each sensor. Although cable-based systems are reliable, the sheer amount of cable required is tremendous, causing complications in survey logistics as well as survey downtime. The need for a cable-free seismic data acquisition system has attracted much attention from contractors, exploration companies, and researchers to lay out the enabling wireless technology and architecture in seismic explorations. This paper gives a general overview of land seismic data acquisition and also presents a current and retrospective review of the state-of-the-art wireless seismic data acquisition systems. Furthermore, a simulation-based performance evaluation of real-time, small-scale wireless geophone subnetwork is carried out using the IEEE 802.11 g technology based on the concept of seismic data acquisition during the geophone listen or recording period. In addition, we investigate an optimal number of seismic samples that could be sent by each geophone during this period.

A Seismic Data Acquisition System Based on Wireless Network Transmission

A seismic data acquisition system based on wireless network transmission is designed to improve the low-frequency response and low sensitivity of the existing acquisition system. The system comprises of a piezoelectric transducer, a high-resolution data acquisition system, and a wireless communication module. A seismic piezoelectric transducer based on a piezoelectric simply supported beam using PMN-PT is proposed. High sensitivity is obtained by using a new piezoelectric material PMN-PT, and a simply supported beam matching with the PMN-PT wafer is designed, which can provide a good low-frequency response. The data acquisition system includes an electronic circuit for charge conversion, filtering, and amplification, an FPGA, and a 24-bit analog-to-digital converter (ADC). The wireless communication was based on the ZigBee modules and the WiFi modules. The experimental results show that the application of the piezoelectric simply supported beam based on PMN-PT can effectively improve the sensitivity of the piezoelectric accelerometer by more than 190%, compared with the traditional PZT material. At low frequencies, the fidelity of the PMN-PT piezoelectric simply supported beam is better than that of a traditional central compressed model, which is an effective expansion of the bandwidth to the low-frequency region. The charge conversion, filtering, amplification, and digitization of the output signal of the piezoelectric transducer are processed and, finally, are wirelessly transmitted to the monitoring centre, achieving the design of a seismic data acquisition system based on wireless transmission.

Migration using sea surface-related multiples: Challenges and opportunities

In marine seismic exploration, it has been well known that sea surface-related multiples can be treated as signals to image the subsurface and provide extended illumination. Previous studies on imaging of multiples have been mainly focusing on its algorithm development and implementation. This paper serves as a tutorial where we systematically investigate the fundamental challenges in the process of imaging of multiples. We first examine the impacts of marine seismic data acquisition parameters: such as offset, trace spacing and streamer towing direction, which are all key elements that control the quality of the images of multiples, and illustrate that 3D towed streamer and OBS surveys are preferable acquisition geometries to apply imaging of multiples. In addition, we investigate the challenges in jointly imaging primaries and multiples and the crosstalk problem in the process, and demonstrate that a Least-Squares inversion based algorithm is effective to address these issues. With the proper handling of all those challenges, imaging of multiples can help to mitigate shallow acquisition footprints, improve salt boundary illumination and enhance the imaging resolution, which allow the identification of drilling hazards and reduction in drilling risks. To apply imaging of multiples in practice, the objective is not to replace but to augment imaging of primaries by providing extra illumination.

Borehole-Driven 3D Surface Seismic Data Processing Using DAS-VSP Data

A 3D surface seismic data acquisition project was conducted simultaneously with 3D DAS-VSP data acquisition in one well in Jilin Oilfield of Northen China. The 3D surface seismic data acquisition project covered an area of 75 km2, and one borehole (DS32-3) and an armoured optical cable with high temperature single mode fiber were used to acquire the 3D DAS-VSP data simultaneously when the crew was acquiring the 3D surface seismic data. The simultaneously acquired 3D DAS-VSP data were used to extract formation velocity, deconvolution operator, absorption, attenuation (Q value), anisotropy parameters (η, δ, ε) as wel as enhanced the surface seismic data processing including velocity model calibration and modification, static correction, deconvolution, demultiple processing, high frequency restoration, anisotropic migration, and Q-compensation or Q-migration. In this project, anisotropic migration, Q-migration was conducted with the anisotropy parameters (η, δ, ε) data volume and enhanced Q-field data volume obtained from the joint inversion of both the near surface 3D Q-field data volume from uphole data and the mid-deep layer Q-field data volume from all available VSP data in the 3D surface seismic surveey area. The anosotropic migration and Q-migration results show much sharper and focussed faults and and clearer subsutface structure.

Investigation of geophysical challenges in land seismic data acquisition in Nigeria: case study of parts of the Niger Delta region

Geophysical analysis was carried out to evaluate the challenges encountered in land seismic exploration within the study area. This analysis cuts across various stages in land seismic acquisition. These stages include the following: the availability of the prospect map as originally planned by the prospect owners—the client, the desk study and planning of this map by the seismology section (planning seismologist) for acquisition convenience and the field implementation of the acquisition which the survey, drill and recording (preloading, shooting, swath move, line check, LAUX crew and recording platform) sections carried out. The challenges observed included environmental challenges, noise interference, weather conditions (statics or electrostatics interference), line break, faulty equipment, wrong detailing, cake or expired explosives, poor or compromised supervision, security and permit challenges. These challenges are peculiar to Nigeria due to inadequate implementation of policies that guide human settlements and activities. Nigeria is within the climate region where most at times it is very impossible to control natural events like cloudy weather, rainfall, thundering and lightening. As such, the problem of static charges interfering with acquired seismic data becomes inevitable, mostly during the rainy season. Almost total dependency on imported technology and lack of readily available experienced manpower also contribute to these challenges, most especially when it has to do with proper inspection of equipment and materials required for the acquisition and supervision processes. Approaches to follow to minimize the observed challenges were equally highlighted.