ADNOC Best Practice, Water Saturation Modeling Short-Cut

The main purpose of this work is to present new approach “short-cut” that can be implemented to build water saturation model “Sw Model” in the static model while honoring Sw_log data and allowing to smoothen transition zone at nearby OWC/FWL depth.

The new concept, which is called “RRT’s Ratio Concept”, is basically linked to numbers of cells that defined based on FZI’s ranges then by utilize those group to re-adjustment the transition zone accordingly.

This work can be applied in case of existing few number of wells in the model with large well-spacing and reservoir STOOIP size, which might required then to use large radius of investigation to distribute Sw_log data between wells weighted on either RRT’s or PORO parameters. By applying this work, at cut-off depth of OWC/FWL depth, all the cells showed high oil saturation will be re-adjustment to be more smoothen to present graduate Sw change with depth as shown in slide-4.

This concept has been tested over many models and the output showed encourage results.

Once the Sw model is be created in the static model, ADNOC new concept to design saturation tables for the dynamic model then can be applied, which would replicate SW static model into dynamic model at high resolution and presents excellent match between Sw_log vs. Sw_pc profiles.

RRT’s Ratio Concept (Sw model adjustment nearby OWC/FWL depth, Case Example)

Radius of investigation =500m Radius of investigation =1000m Radius of investigation =5000m

Radius of investigation =7000m Radius of investigation =10000m

By using short radius of investigation to distribute Sw_log data, there will be allot of gaps developed between the wells due to short distribution distance.

By using large radius of investigation to distribute Sw_log data, there will be overlap of Sw matrix which would exceed OWC/FWL surface depth.

RRT’s Ratio Concept (Basic Workflow 1/3)

Create “FZI” model using PERM & PORO parameters If the layer is barrier, then FZI = 0.0

Filter the static model to show only cells above OWC/FWL depths Assume the numbers of cells is 12,500 active cells

The proposed total numbers of target RRT’s group to be = 5 RRT’s (this number can be defined from 3 to 7 based on target resolution) Good RRT = 1 & Tight RRT = 5

Use RRT Ratio model to identify numbers of cells and FZI ranges per each RRT as the following example:

Remove the filter and generate RRT model per each case scenario using FZI ranges You can create as many cases are needed with different setup of RRT’s ratio

Use deterministic approach to distribute Sw_log data weighed on RRT’s model per each case scenario At this stage, you don’t need to cut-off the Sw values below FWL/OWC depth i.e. ( just leave it)

Case-1 Case-2 Case-3

RRT’s Ratio Concept (Basic Workflow 2/3)

Review and plot: (1) PORO vs. PERM per RRT’s Per each generated case scenario, (2) Sw_log data vs. Height above FWL per RRT’s

Calculate R2 value per each case scenario and select the case with highest R2 value The selected case scenario should reflect and represent the best RRT’s classification setup that support better tie-in with Sw_log

Use deterministic approach to distribute Sw_log data weighed on RRT’s model 2 since its show the highest R 2 score At this stage, just use cut-off the Sw values below FWL/OWC depth i.e. (Sw = 1.0 below OWC/FWL depth)

Case-1

Case-2

Case-3

PORO

PERM

PORO

PERM

PORO

PERM

Sw_log

Hei

ght a

bove

FW

L

Sw_log

Hei

ght a

bove

FW

L

Sw_log

Hei

ght a

bove

FW

L

R2 = 0.75

R2 = 0.87

R2 = 0.71

RRT’s Ratio Concept (Basic Workflow 3/3)

In order to adjustment Sw model at OWC/FWL depth from low Sw to reasonable Sw trend per each RRT’s classification to introduce simple transition zone, a new parameter “COR” to be generated as the following example:

Assume that the FWL depth at 9900 TVDss. Create FWL model:

FWL = 9900 – Depthif FWL<0.0 then FWL=0.0 endif

Create parameter “COR” = 0.0 Filter Sw model to show only RRT1 cells then

COR = 1/(1+(FWL/A)^B) 0.0 <= COR <= 1.0where A & B are variables per RRTA* can be ranged between 0.1 to 50.0 (recommended low value)B ** can be ranged between 0.5 to 7.0 (recommended high value)

Repeat Filter Sw model for RRT2 and calculate “COR” with A & B parameter for RRT2, until complete for all RRT’s Create Swnew = Sw + ( Sw x COR )

If Swnew > 1.0 the Swnew = 1.0 endifThis step can be repeated as many time to improve Sw trend per RRT at transition zone by Sw = Sw new and thenrecalculate Swnew2 = Sw + ( Sw x COR )

Once Sw model is been accepted, another workflow to generate Sw_pc will be discussed in the near future. The adjustment of Sw values will be applied only at cells nearby FWL and no change of Sw values for cells in oil pool.

RRT1,Good RRT5, Tight

COR CORH

eigh

t abo

ve F

WL

Hei

ght a

bove

FW

L

RRT’s Ratio Concept (Sw model adjustment nearby OWC/FWL depth, Case Example)

Iteration # 1 Iteration # 3

Iteration # 5 Iteration # 7

RRT’s Ratio Concept (additional RRT’s classification to be considered)

Different classifications, groups and range of RRTs can be defined and

selected to correct and adjustment Sw only at nearby FWL and in transition

zone