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Geomodeller’s Forum Newsletter #1

In this issue:

What is the this

stationarity analysis

How can this

analysis help?

Which data type can

be used in this

analysis?

Examples of

analysis

December 14, 2014Stationarity Analysis

Stationarymeans the spatially separated parts of the data that iseffectively controlled by the same underlying system,or come from the same probability distribution.

If the reservoir has multiple stations, it implies thatcertain parts of the data should be treated differentlywith respect to the other parts in property modelingworkflow. A certain statistical analysis would revealstations in the dataset of interest.

Benefit of the analysis

Stationarity analysis is used to identify continuity of geological features and

the presence of lateral and/or vertical trends in data set. The importance of

this behavior can be reflected in the method for predictions.

Q: What is the right time to perform this analysis?

A: After loading all data, modeler has to perform this analysis

Q: What kind of data can be used?

A: Any and all static properties and even some of the dynamic data can be

used for this analysis.

Q: What is the consequence of missing this step?

A: Property modeling results would be more uncertain especially in those

area that should be treated differently.

“Successful property

prediction system relies on

the accuracy of input data and

existence of captured

stations. When the

investigation of stationarity is

performed, the results may

show spatially existing trends

in entire reservoir or in certain

direction and region...”

You win, we win

Methodology to perform stationary analysis:

Spatial distribution of properties indicates the existence of stationary characteristics

of the data. Areal distribution of the input data reveal the evidence. You can

generate following plots to make stationarity analysis:

Map view of average porosity values at well location per sub-zones

Cross plot of

porosity vs depth

Porosity vs X-location

Porosity vs Y-location

Permeability vs depth and locations

Calculating or generating local mean of property distribution

In this map view, circles with colorcoding demonstrate the distributionof porosity and the triangles showspermeability. The average values ofwell data from red to pink decreasesfor both properties. Polygons showgas oil contact in green and oilwater contact in blue.East side of the field manifest higherproperties than the west side.Moreover a depth trend from crestto flank decimates the rock quality.Yet, the trend is different in differentdirection. In such a case a singletrend can not be used for modeling.

Reservoir property variations exhibiting certain features over a wide range of

scales are crucial to be identified from the macro-scale of well log up to inter well

locations and finally to field scale. Connectivity, isotrophy, volumetrics and local

sweep efficiency are investigated generally through static modeling and dynamic

simulation work. Early indications of both transmissibility and storage capacity of

the rock around the field can be obtained through stationarity analysis.

Above log porosity versus depth plot color coded by the location (pink to red

designates north to south direction) indicates that the data in the south part of the

field (red points) shows totally different behavior then the north part (pink to blue).

Areal distribution of the input data reveals the evidence for the stationary

characteristics of the data. Distribution of average porosity values at well location in

each sub-zones demonstrates the fact about the stations. Different areas and

directions (North, Middle Flank and South) obviously show different trends

Average permeability map on the

left indicates existence of no trend

or stationaries. Low and high

permeability points are scattered

around the field. This might be due

to faults and fractures or abrupt

facies change. Instead of spatial

relation, for permeability modeling,

another correlation has to be used

Stationary analysis can be applied various data in various domain. General practice

in the industry is to analyze static data spatially to define stations. Data set mixing

both the spatial and the time dimensions can be also used in this type of analysis.

Stationarity assumptions along the spatial plane do not translate into time domain.

Special care is therefore necessary when dealing with dynamic data. For instance,

production data constitute a 2-dimensional spatial plane per well and also varies

timely.

Instead of mapping production data to understand the reservoir, mapping change in

production or pressure drop would be more meaningful to manifest depletion of the

reservoir at well locations. The ability to define connectivity, sweep and potential

areas of improvement, change in dynamic parameters can be displayed on 2D

special geometry.

The result of average values for a given zone can be displayed as continues value

points or discrete colored blocks which might help more to see stations with same

colors. This can be achieved to generate large size grids then upscaling the logs into

3D model grids.

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Disclaimer

The technical offer, recommendations and conclusions contained in this proposal are based on the data provided to us and our understanding. The proposal was prepared according to the standard of skill and care that is expected of a professionally qualified and experienced experts. However, Grenergy LLC does not warrant the accuracy or correctness of any results, conclusions or recommendations and accept no liability for any loss, damage or costs that may be incurred or sustained through the use of the results, conclusions or recommendations of this proposal.

Grenergy LLC is dedicated to develop greentechnologies for the oil and gas industryworldwide, specializing on the treatment of oil,water, gas, gas conditioning and renewableenergy resources.

Including reduction of high TAN crude oil andzero emission oil & gas flaring technologies wehave developed are all patented. Our productsare designed to meet the requirements ofenvironmental standards and local legislations.

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info@grenergyllc.com

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