PTQ Q2 2025 Issue

onsets, were included for comparison. The non-linearity in the blend onsets was very well predicted by the model. Such validation was conducted for more than 40 crude blends, including binary (two-source) and ternary (three- source) blends. The onset data for the source oils covered different titration solvents and temperatures ranging from 20°C to 150°C. Overall, MFCCT reported a high predictive accuracy with an average absolute deviation (AAD) of 0.17 mL/g. This result demonstrated its effectiveness in captur- ing the asphaltene phase behaviour of blends. Compatibility assessment guidelines Beyond onset predictions, a normalised measure called Blend Compatibility Index (BCI) has been developed to assess blend stability. This index provides a measure of non-linearity. Specifically, the index illustrates the blends’ uniqueness when compared to the source oils in terms of asphaltene solubility. It is dimensionless and calculated at 60°F and 1 atm as the ratio of predicted onsets to the weight-averaged onset. A BCI value greater than zero indicates a stable blend, while a value of zero signals an unstable blend. Table 1 provides an interpretation of BCI for blends. By analysing crude blend stability using a structured compatibility index, the refineries can identify problematic combinations and optimise blending proportions. Further, BCI may offer insights into the preferred blending order of source crudes, though this aspect has not been assessed due to a lack of data. Following are general compatibility assessment guide- lines based on the tested datasets. These guidelines are subject to refinement as more data becomes available. • Low risk (onset ≥ 0.6; BCI > 0): stable blend with com- patible source oils. • High risk (0.2 < onset < 0.6; BCI > 0): potentially sta- ble blend and requires BCI analysis to identify problematic source oils • Not recommended (onset ≤ 0.2; BCI ≥ 0): unstable blend and not advisable for processing.

3.5

Measured Weighted-average based on source oils Predicted

3.0

2.5

2.0

1.5

1.0

0.5

Blend: Oil 1 + Oil 2 75

100

wt% of Oil 2 in the blend

Note that the onset values for the assessment are expressed in mL of n-heptane/g of sample. These guidelines are not established for other titrating solvents. However, BCI analysis can still be performed. To illustrate the effectiveness of the MFCCT, the follow- ing case studies highlight different scenarios where crude compatibility assessments are evaluated by the refiners. Case study 1 This case study involves data from a refiner who provided detailed source oil information, including the P-Value as the onset data. The dataset also included the proportions of six blends and their respective P-Values. The refiner’s assess - ment classified these blends into three categories: • Blend 1 was deemed acceptable for processing. • Blends 2-5 were categorised as ‘business-to-risk’. • Blend 6 was determined unsuitable for processing. MFCCT was used to independently evaluate these blends based on P-Value and the BCI. Note that P-Value = 1+onset in mL/g. As illustrated in Table 2 , the tool’s predictions aligned perfectly with the refinery’s initial classification, Figure 2 Predicted onsets compared against the measured onsets for Oil 1 and Oil 2 blends

MFCCT predictions of P-Values alongside client data, demonstrating alignment between predicted and actual outcomes

Volume %

Source crude

P-Value

Blend 1

Blend 2

Blend 3

Blend 4

Blend 5

Blend 6

Crude 1 Crude 2 Crude 3 Crude 4 Crude 5 Crude 6 Crude 7 Crude 8

1.68 1.39 2.95 1.28 1.08 1.64 2.66 1.63

12.5 12.5 12.5 12.5 12.5 12.5 12.5 12.5 1.64

5 5

35 35

8 0 0 8 0 0 8

3 0 2 0 7 0

12 0.5 25 50 10 0.5

1.5

5 8

1.5 1.5

10 1.5 64

5 2

P-Value

1.58

1.40

1.46

1.40

1.18

Refinery client

Proceed

Business-to-risk

Not recommended

Assessment

P-Value

1.57 0.69

1.62 1.03

1.36 0.60

1.42 0.66

1.40 0.59

1.09 0.35

BCI

KBC (MFCCT)

Low risk

High risk

Not recommened

Assessment

Compatible

Potentially incompatible crude proportions

Table 2

PTQ Q2 2025