2D/3D/4D Seismic Interpretation
Our proprietary reverse engineered seismic interpretation methods and techniques are very unique to LEAN GeoSolutions. If your company is actively exploring in AVO plays, there is no need for you to interpret every anomaly you see on seismic. We are here to help you very quickly identify the low hanging fruits, to save you time and money. Our interpretation strategy is based on advanced rock physics and AVO modelling and deep understanding of different basins, coupled with automation to quickly identify the most critical ones.
Rock Physics Diagnostics
Rock physics can do magic for you, only if you know which buttons to push! For conventional deep-water plays, we can show you how to construct the basin's depositional model/history from a cross plot! Not only that, but also tell you what seismic anomalies you should interpret and which one you should avoid, following a proven sorting criteria.
From Mineralogy, compaction (mechanical or chemical), sorting, porosity, stiffness of the rock frame and fluid type we can tell you what AVO response you should expect on seismic and as a function of depth. We can also help you differentiate between a genuine AVO response and a likely false positive!
LEAN GeoSolutions has the capabilities to do a full rock physics evaluation using log data. This includes petrophysical evaluation, QC of logs, fluid substitution including those in challenging environments such as thin beds, AVO forward modelling, cross plotting, trend derivation, rock physics modelling, which provides the link between the reservoir rock and fluid properties and the elastic properties. At LEAN GeoSolutions, we believe rock physics is undoubtedly the key to unlock the potential of any AVO play, worldwide, only if you use our secret recipe.
For unconventional reservoirs we can help you construct a methodology for characterizing such reservoirs using rock physics, through the understanding of the effects of organic matter, mineralogy, micro fractures, porosity, etc. We can then integrate the findings from rock physics into seismic inversion workflows or attributes to help you identify hydrocarbon sweet-spot.
Pre-Stack Interpretation, AVO, DRhI
We provide a wide range of services for pre-stack seismic data conditioning and interpretation. This includes random and coherent noise removal, velocity analysis, gather flattening, multiple removal, spectral balancing, wavelet shaping, bandwidth extension, amplitude scaling and many more.
We also provide a wide range of AVO products such as creating angle substacks for AVO interpretations, intercept and gradient volumes, AVO class volume, A/B volumes and many more . We can also generate AVO synthetic gathers from well data for comparison with data gathers, to ensure consistency between the expected AVO response from well data and that observed on seismic gathers. This will give you more confidence when de-risking your prospects.
LEAN GeoSolutions has the in-house compute power to handle tens of Terabytes of data with no issues.
Seismic Inversion
From colored inversion to petro-elastic seismic inversion where we invert for elastic properties (e.g. acoustic impedance, Vp/Vs and density) and petrophysical parameters (e.g. porosity, volume of clay and water saturation). LEAN GeoSolutions has the capabilities to invert all input seismic stacks simultaneously for the best fitting earth model. Not only that, but we can also handle all the preparation work including gather conditioning and the generation of a closely spaced angle substacks to be used as input for the pre-stack inversion.
Play Analysis (Leads, Prospects)
Using rock physics, we can help you screen for leads and rank your prospects, especially in AVO plays. We can also put a confidence number on your subsalt prospects with amplitude response.
Acquisitions & Farm-out Opportunities
We can join you to evaluate an opportunity in a data room and help you evaluate the data presented to you.
3D Close-the-Loop
In a 3D Close-the-Loop workflow, we demonstrate how rock physics, when coupled with seismic interpretation, can lead to building geologic models that are consistent with seismic data. In this case, a series of geologic model scenarios (no limit on number) can be converted into elastic models (P-velocity, S-velocity, Density, Acoustic Impedance, Shear Impedance, Velocity ratio) using a rock physics model derived from well log data. The elastic models are then used as input for generating synthetic seismic volumes using the standard AVO approximations such as the Aki-Richards, for comparison against the seismic data. The main objective here is to validate and ensure consistency between the geologic model scenarios and the seismic data.
4D Seismic Feasibility & Interpretation (Streamer, OBC & OBS)
In a 4D feasibility study, we take the dynamic simulation models at different time steps, post the projected first oil date as input, and convert them into volumes of elastic properties (P-velocity, S-velocity, Density, Acoustic Impedance, Shear Impedance, Velocity ratio) from which synthetic seismic volumes using a rock physics model are calculated.
The well-based rock physics model accurately predicts the changes in elastic properties as a function of changes in effective stress and fluid saturations. The outcome of this feasibility study will help us decide on the optimum time for acquiring the first monitor survey designed to capture the 4D changes due to production effects. There is always a critical window of opportunity which should not be missed for acquiring a repeat survey.
As for the 4D interpretation, first we ensure that the 4D surveys meet the basic criteria required for 4D interpretation, by calculating a series of QC attributes such as the NRMS. We then relate the observed changes between the baseline and monitor surveys either in seismic amplitudes, time-shifts, time-strains and inverted elastic properties (e.g. acoustic impedance, shear impedance and velocity ratio) to changes in reservoir properties (e.g. pressure, porosity and fluid saturations).
4D Close-the-Loop
Forward-looking 4D seismic feasibility studies, determine whether an observable future time-lapse signal, due to production effects will likely be caused by pressure depletion, saturation change, or both combined. However, in a 4D CtL study, the forward-modeled synthetic time-lapse seismic response is directly compared to time-lapse seismic data for evaluation and interpretation.
In both cases, synthetic time-lapse seismic volumes are generated using a reservoir dynamic simulation model as input. Rock and fluid property relations derived from appropriate well logs and core measurements are combined in a single rock-physics model. The rock-physics model is used to establish the link between static and dynamic reservoir rock and fluid properties and their corresponding elastic properties.
Uniaxial strain core laboratory measurements are used to determine the relationship between the rock’s bulk and shear moduli and the changes in effective stress. A reasonable repeatability of the synthetic baseline survey, similar to that achieved in real seismic data, is assumed. Seismic amplitudes and/or elastic attributes, such as P-impedance and S-impedance at the reservoir level, are then extracted from the baseline and monitor synthetic data. The baseline and monitor synthetic data differences are then compared against real-data 4D differences for interpretation. Assuming a representative rock-physics model has been established, any mismatch between the synthetic and real 4D signal reflects the inaccuracy of the dynamic simulations and prompts an update of the reservoir dynamic model and potentially the static model. Pressure and saturation changes are adjusted until a reasonable match is achieved. A 3D CtL is a pre-requisite for a 4D feasibility study and 4D Ctl.
LEAN GeoSolutions experts have significant experience in building 3D & 4D CtL workflows as well as 4D interpretation.
De-Risking Stratigraphic Traps
Unlike Structural traps which are typically formed as a result of changes in the structure of the subsurface, due to tectonic, diapiric, gravitational and compaction related processes, stratigraphic traps are formed from changes in rock type or pinch-outs, unconformities, or other sedimentary features such as reefs or buildups. Stratigraphic traps can be very risky unless they are in an AVO play, where AVO, potentially coupled with a DHI are good indicators of a fluid type and sand quality. That’s where rock physics diagnostics and LEAN GeoSolutions experts can help you de-risk these prospects. We don’t chase anomalies on seismic data, we quickly screen for a specific seismic response that is inline with the fundamental laws of nature. Moreover, the AVO response should be consistent with a predictive rock physics model, valid for a combination of rock and fluid scenarios, and at all depths points in the subsurface.
Subsalt DHIs
Subsalt DHIs is a subject that is not talked about that often these days in oil & gas companies or at conferences. It is considered today’s dim zone of geophysics! However, LEAN GeoSolutions has developed a methodology that will help you de-risk such prospects, where an amplitude response is observed under salt. The outcome of this technique becomes even more reliable, especially if there are wells nearby to be used in the study. The outcome of a study as such will tell you whether the amplitude you see on seismic is indeed genuine or simply false. It will also help you decide whether your data requires reprocessing. We can simply help you put a confidence number on the amplitudes associated with your subsalt prospect. This integrated workflow is compute-intensive and requires deep knowledge in rock physics and seismic imaging. Moreover, not only LEAN GeoSolutions has the capabilities to help you de-risk your amplitude supported subsalt prospects, but also has the in-house compute power to handle heavy computations.
Acoustic Logs (QC - Editing to Interpretation - Modeling)
Lean GeoSolutions can help you with your acoustic logs (sonic, shear sonic, and density logs), from QC/editing (company repositories are full of good but unedited log data, and that includes logs from modern tools such as Sonic Scanner; not only old BHC sonic logs) to interpretation/modeling, and we are here to help! A good acoustic logs database is essential for geophysics and geomechanics. Acoustic data cleaning/recovery by experts is cheaper and faster than reprocessing. And it only needs to be done once.
We can also do standard petrophysical evaluations for you, using log and core data, where we calculate porosity, fluid saturations, lithology logs, mineral logs and more.
