Processing and quality-control strategies for consistent time-lapse seismic attributes: A case history on an internal blowout using vintage data

Geophysics ◽  
2017 ◽  
Vol 82 (4) ◽  
pp. B135-B146 ◽  
Author(s):  
Hung Nho Dinh ◽  
Mirko van der Baan ◽  
Martin Landrø
Keyword(s):  
Quality Control ◽  
Control Strategies ◽  
Time Lapse ◽  
Reflection Seismic ◽  
The North ◽  
Processing Strategies ◽  
3D Data ◽  
Site Survey ◽  
The North Sea ◽  
Legacy Data

Many vintage reflection seismic surveys exist that have nonrepeated acquisition geometries or final-stacked/migrated sections are obtained using different or nonconsistent processing flows. This may lead to derived time-lapse attributes that are not internally consistent or even conflicting. For instance, we have focused on a subsurface gas blowout that occurred in 1989 in the Norwegian sector of the North Sea. The 2D site survey data were acquired in 1988 and 1990, and the 3D data were acquired in 1991 and 2005. The various sets of legacy data are plagued by poor repeatability among data acquisitions, application of different processing strategies, missing prestack data, and the presence of multiples. All of these factors severely complicate even qualitative interpretation of the gas migration associated with the underground blowout. Careful time-lapse processing may provide useful information even from such challenging legacy data by first computing numerous attributes including instantaneous amplitude differences, time shifts, time-lapse attenuation, and impedance inversions. Then, judicious quality control, invoked by comparing the various attributes, was used to check for internally consistent results.

Time-lapse seismic surveys in the North Sea and their business impact

2000 ◽  
Vol 19 (3) ◽  
pp. 286-293 ◽  
Author(s):  
Klaas Koster ◽  
Pieter Gabriels ◽  
Matthias Hartung ◽  
John Verbeek ◽  
Geurt Deinum ◽  
...  
Keyword(s):  
North Sea ◽  
Time Lapse ◽  
Seismic Surveys ◽  
Business Impact ◽  
The North ◽  
The North Sea

Delineation of tunnel valleys across the North Sea coastline, Denmark based on reflection seismic data, boreholes, TEM and Schlumberger soundings

2016 ◽  
Vol 2016 (1) ◽  
pp. 1-10
Author(s):  
Theis Raaschou Andersen ◽  
Flemming Jorgensen ◽  
Steen Christensen
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Reflection Seismic ◽  
The North ◽  
The North Sea

scholarly journals Reconstructing North Sea palaeolandscapes from 3D and high-density 2D seismic data: An overview

2014 ◽  
Vol 93 (1-2) ◽  
pp. 31-42 ◽  
Author(s):  
S. van Heteren ◽  
J.A.C. Meekes ◽  
M.A.J. Bakker ◽  
V. Gaffney ◽  
S. Fitch ◽  
...  
Keyword(s):  
North Sea ◽  
Spatial Scales ◽  
Building Blocks ◽  
High Density ◽  
Glacial Cycles ◽  
The North ◽  
3D Data ◽  
Hunting And Gathering ◽  
Environmental Setting ◽  
The North Sea

AbstractThe North Sea subsurface shows the marks of long-term tectonic subsidence. Much of it contains a thick record of glacial and interglacial deposits and landscapes, formed during multiple glacial cycles and the associated regressions and transgressions during the past two million years. At times of lower sea level than today, areas that are presently submerged were fertile lowlands more favourable for hunting and gathering than the surrounding upland. These drowned lowlands are not captured by traditional 1:250,000 geological maps of the North Sea subsurface because the underlying seismic and core data are commonly too widely spaced to achieve this. Palaeolandscape mapping requires identification of building blocks with spatial scales in the order of 1 km or less. As high-density 2D and high-quality 3D seismics are becoming available for an increasing part of the North Sea, glacial and interglacial palaeolandscapes can be reconstructed for more and more areas. An overview of published palaeolandscape reconstructions shows that shallow time slices through 3D data provide map views that are very suitable for the identification of landscape elements. For optimal results, each time slice needs to be validated and ground-truthed with 2D seismics and with descriptions and analyses of cores and borehole samples. Interpretations should be made by teams of geoscientists with a sufficiently broad range of expertise to recognise and classify even subtle or unfamiliar patterns and features. The resulting reconstructions will provide a context and an environmental setting for Palaeolithic, Mesolithic, and Neolithic societies and finds.

Enhancements in Fracturing Fluid Engineering Reawakens a North Sea Giant

2022 ◽  
Author(s):  
Asif Hoq ◽  
Yann Caline ◽  
Erik Jakobsen ◽  
Neil Wood ◽  
Rob Stolpman ◽  
...  
Keyword(s):  
Quality Control ◽  
North Sea ◽  
Large Scale ◽  
High Shear ◽  
Testing Procedures ◽  
Coiled Tubing ◽  
The North ◽  
Track Record ◽  
Enhanced Production ◽  
The North Sea

Abstract The Valhall field, operated by AkerBP, has been a major hub in the North Sea, on stream for thirty-eight years and recently passed one billion barrels of oil produced. The field requires stimulation for economical production. Mechanically strong formations are acid stimulated, while weaker formations require large tip-screenout design proppant fractures. Fracture deployment methods on Valhall have remained relatively unchanged since the nineties and are currently referred to as "conventional". Those consist in a sequence of placing a proppant frac, cleaning out the well with coiled tubing, opening a sleeve or shooting perforations, then coil pulling out of hole pumping the proppant frac. For the past few years, AkerBP and their service partners have worked on qualifying an adapted version of the annular coiled tubing fracturing practice for the offshore infrastructure - a first for the industry, which has been a strategic priority for the operator as it significantly reduces execution time and accelerates production. As with all technology trials, the implementation of this practice on Valhall had to begin on a learning curve through various forms of challenges. Whilst investigating the cause and frequency of premature screenouts during the initial implementation of annular fracturing, the team decided to challenge the conventional standards for fluid testing and quality control. Carefully engineered adjustments were made with regards to high shear testing conditions, temperature modelling, and mixing sequences, these did not only identify the root cause for the unexpected screenouts, but also helped create the current blueprint for engineering a robust fluid. Since the deployment of the redefined recipe, adjusted testing procedures and changes made to the stimulation vessel, there have not been any cases of fluid induced screenouts during the executions. The fewer types of additives now required for the recipe have lowered the cost of treatments and the lower gel loading leads to reduced damage in the fractures, thereby contributing to enhanced production over the lifetime of the wells. This paper describes the investigation, findings and the resulting changes made to the fluid formulation and quality control procedures to accommodate for high shear and dynamic wellbore temperature conditions. It discusses the rationale behind the "reality" testing model and, proves that significant value is created from investing time in thoroughly understanding fluid behaviour in the lab, prior to pumping it on large-scale capital-intensive operations. The study demonstrated that there is always value in innovating or challenging pre-conceived practices, and the learnings from this investigation significantly improved the track record for annular fracturing on Valhall, redefined fluid engineering for the North Sea and will inform future annular fracturing deployments on other offshore assets around the world.

Time-Lapse Seismic Analysis of the North Sea Fulmar Field

1998 ◽  
Author(s):  
D.H. Johnston ◽  
R.S. McKenny ◽  
T.D. Burkhart
Keyword(s):  
North Sea ◽  
Seismic Analysis ◽  
Time Lapse ◽  
The North ◽  
The North Sea

A new approach to separate seismic time-lapse time shifts in the reservoir and overburden

Geophysics ◽  
2017 ◽  
Vol 82 (6) ◽  
pp. Q67-Q78 ◽  
Author(s):  
Yi Liu ◽  
Martin Landrø ◽  
Børge Arntsen ◽  
Joost van der Neut ◽  
Kees Wapenaar
Keyword(s):  
Linear Equations ◽  
Time Lapse ◽  
Velocity Model ◽  
Borehole Data ◽  
Lapse Time ◽  
Surface Reflection ◽  
The North ◽  
Reflection Data ◽  
The North Sea ◽  
Velocity Changes

For a robust way of estimating time shifts near horizontal boreholes, we have developed a method for separating the reflection responses above and below a horizontal borehole. Together with the surface reflection data, the method uses the direct arrivals from borehole data in the Marchenko method. The first step is to retrieve the focusing functions and the up-down wavefields at the borehole level using an iterative Marchenko scheme. The second step is to solve two linear equations using a least-squares minimizing method for the two desired reflection responses. Then, the time shifts that are directly linked to the changes on either side of the borehole are calculated using a standard crosscorrelation technique. The method is applied with good results to synthetic 2D pressure data from the North Sea. One example uses purely artificial velocity changes (negative above the borehole and positive below), and the other example uses more realistic changes based on well logs. In the 2D case with an adequate survey coverage at the surface, the method is completely data driven. In the 3D case in which there is a limited number of horizontal wells, a kinematic correct velocity model is needed, but only for the volume between the surface and the borehole. Possible error factors related to the Marchenko scheme, such as an inaccurate source wavelet, imperfect surface multiples removal, and medium with loss are not included in this study.

Real-Time Quality Control of Wave Observations in the North Sea

1994 ◽  
Vol 11 (6) ◽  
pp. 1611-1624
Author(s):  
María Paula Etala ◽  
Gerrit Burgers
Keyword(s):  
Quality Control ◽  
Real Time ◽  
North Sea ◽  
The North ◽  
The North Sea

Time‐lapse seismic analysis of the North Sea Fulmar Field

1997 ◽  
Author(s):  
David H. Johnston ◽  
Robert S. McKenny ◽  
Tucker D. Burkhart
Keyword(s):  
North Sea ◽  
Seismic Analysis ◽  
Time Lapse ◽  
The North ◽  
The North Sea
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