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Copyright of Shell Global Solutions (US) Inc. 2014

COMPRESSOR COAST-DOWN EVALUATION STUDY

USING DYNSIM

Presented at the 2014 Schneider Electric Software Global

Customer Conference

September 30 - October 2, 2014

Orlando, Florida, USA

Asit Mardikar, Sonia Pusha & Ashok Dewan(*)

* Speaker, To Whom Correspondence May Be Addressed:

Shell Global Solutions (US) Inc., Shell Technology Center-Houston,

3333 Highway 6 South, Houston, TX 77082-3101, USA

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DEFINITIONS & CAUTIONARY NOTE

Reserves: Our use of the term “reserves” in this presentation means SEC proved oil and gas reserves.

Resources: Our use of the term “resources” in this presentation includes quantities of oil and gas not yet classified as SEC proved oil and gas reserves. Resources are

consistent with the Society of Petroleum Engineers 2P and 2C definitions.

Organic: Our use of the term Organic includes SEC proved oil and gas reserves excluding changes resulting from acquisitions, divestments and year-average pricing

impact.

Resources plays: our use of the term ‘resources plays’ refers to tight, shale and coal bed methane oil and gas acreage.

The companies in which Royal Dutch Shell plc directly and indirectly owns investments are separate entities. In this presentation “Shell”, “Shell group” and “Royal Dutch

Shell” are sometimes used for convenience where references are made to Royal Dutch Shell plc and its subsidiaries in general. Likewise, the words “we”, “us” and “our” are

also used to refer to subsidiaries in general or to those who work for them. These expressions are also used where no useful purpose is served by identifying the particular

company or companies. ‘‘Subsidiaries’’, “Shell subsidiaries” and “Shell companies” as used in this presentation refer to companies in which Royal Dutch Shell either directly

or indirectly has control, by having either a majority of the voting rights or the right to exercise a controlling influence. The companies in which Shell has significant influence

but not control are referred to as “associated companies” or “associates” and companies in which Shell has joint control are referred to as “jointly controlled entities”. In this

presentation, associates and jointly controlled entities are also referred to as “equity-accounted investments”. The term “Shell interest” is used for convenience to indicate

the direct and/or indirect ownership interest held by Shell in a venture, partnership or company, after exclusion of all third-party interest.

This presentation contains forward-looking statements concerning the financial condition, results of operations and businesses of Royal Dutch Shell. All statements other

than statements of historical fact are, or may be deemed to be, forward-looking statements. Forward-looking statements are statements of future expectations that are

based on management’s current expectations and assumptions and involve known and unknown risks and uncertainties that could cause actual results, performance or

events to differ materially from those expressed or implied in these statements. Forward-looking statements include, among other things, statements concerning the

potential exposure of Royal Dutch Shell to market risks and statements expressing management’s expectations, beliefs, estimates, forecasts, projections and assumptions.

These forward-looking statements are identified by their use of terms and phrases such as ‘‘anticipate’’, ‘‘believe’’, ‘‘could’’, ‘‘estimate’’, ‘‘expect’’, ‘‘intend’’, ‘‘may’’, ‘‘plan’’,

‘‘objectives’’, ‘‘outlook’’, ‘‘probably’’, ‘‘project’’, ‘‘will’’, ‘‘seek’’, ‘‘target’’, ‘‘risks’’, ‘‘goals’’, ‘‘should’’ and similar terms and phrases. There are a number of factors that could

affect the future operations of Royal Dutch Shell and could cause those results to differ materially from those expressed in the forward-looking statements included in this

presentation, including (without limitation): (a) price fluctuations in crude oil and natural gas; (b) changes in demand for Shell’s products; (c) currency fluctuations; (d) drilling

and production results; (e) reserves estimates; (f) loss of market share and industry competition; (g) environmental and physical risks; (h) risks associated with the

identification of suitable potential acquisition properties and targets, and successful negotiation and completion of such transactions; (i) the risk of doing business in

developing countries and countries subject to international sanctions; (j) legislative, fiscal and regulatory developments including potential litigation and regulatory measures

as a result of climate changes; (k) economic and financial market conditions in various countries and regions; (l) political risks, including the risks of expropriation and

renegotiation of the terms of contracts with governmental entities, delays or advancements in the approval of projects and delays in the reimbursement for shared costs;

and (m) changes in trading conditions. All forward-looking statements contained in this presentation are expressly qualified in their entirety by the cautionary statements

contained or referred to in this section. Readers should not place undue reliance on forward-looking statements. Additional factors that may affect future results are

contained in Royal Dutch Shell’s 20-F for the year ended 31 December, 2013 (available at www.shell.com/investor and www.sec.gov ). These factors also should be

considered by the reader. Each forward-looking statement speaks only as of the date of this presentation, Oct 2, 2014. Neither Royal Dutch Shell nor any of its subsidiaries

undertake any obligation to publicly update or revise any forward-looking statement as a result of new information, future events or other information. In light of these risks,

results could differ materially from those stated, implied or inferred from the forward-looking statements contained in this presentation. There can be no assurance that

dividend payments will match or exceed those set out in this presentation in the future, or that they will be made at all.

We use certain terms in this presentation, such as discovery potential, that the United States Securities and Exchange Commission (SEC) guidelines strictly prohibit us from

including in filings with the SEC. U.S. Investors are urged to consider closely the disclosure in our Form 20-F, File No 1-32575, available on the SEC website www.sec.gov.

You can also obtain this form from the SEC by calling 1-800-SEC-0330.

Oct 2, 2014 2


AGENDA

Background

Study Objectives

Methodology

Model Scope

Scenarios

Scenario Results

Analysis

Conclusions

Other Observations

Oct 2, 2014 3


BACKGROUND (1 OF 5)

Centrifugal compressors are subject to transient events, such as

emergency shutdowns, which can cause high energy surges.

The rate at which a compressor spins down after a trip (Coast-

down rate) can have a significant impact on whether the

compressor enters a high energy surge situation or not.

Oct 2, 2014 4


BACKGROUND (2 OF 5)

Difference in initial coastdown rate predictions

Oct 2, 2014 5


BACKGROUND (3 OF 5)

Leads to very different compressor surge behaviour

Oct 2, 2014 6


BACKGROUND (4 OF 5)

Fast initial coastdown prediction can result in significant

oversizing Oct 2, 2014 7


BACKGROUND (5 OF 5)

Compressor Coastdown rate after a trip can be an important

determinant in

Anti-surge valve sizes and their open/close timings

Design issues like hot/cold gas bypass arrangements

Suction/Discharge Volumes and other parameters

Hence it was decided to evaluate DYNSIM’s capabilities in this

aspect.

The study also took the opportunity to evaluate Cascade Control

via Selector Block (multiple Master Controllers) in DYNSIM.

Oct 2, 2014 8


STUDY OBJECTIVES

Behaviour of compressor during Coastdown Trip

Run scenarios where Compressor is tripped at given operating conditions.

Review predicted Compressor speed Coastdown rates and compare with

actual plant data.

Evaluation of Back Initialization option for cascade controllers in

DYNSIM

Run Scenarios where Cascade Controller with Selector is put in Local Auto

mode and then put back in Cascade.

Review whether backtracking of selected output is correctly transmitted to non-

selected controllers.

Verify whether Set Point (SP) correctly tracks Present Value (PV), for specified

controller during above transition.

Oct 2, 2014 9


METHODOLOGY

A model of a Compressor Facility in an upstream asset was built

in DYNSIM 5.1.

This model was validated for Steady State predictions and

Dynamic behaviour against plant data and also against a

previously validated model built for engineering studies.

The DYNSIM 5.1 model was then used to run several scenarios

for compressor coastdown.

Oct 2, 2014 10


MODEL SCOPE (1 OF 2)

The dynamic simulation study scope included the following:

Export Gas Compressor Suction Scrubber V-101

Export Gas Compressor K-101

Export Gas Compressor Discharge Cooler E-101

Export Gas Compressor Anti-surge Valve XV- 101

Export pipeline

The model also included associated piping within the compressor

platform, bridge piping, control valves, shut down valves, and

blow down valves.

Oct 2, 2014 11


MODEL SCOPE (2 OF 2)

SCHEMATIC FOR EXPORT GAS COMPRESSOR

Oct 2, 2014 12


SCENARIOS

The following scenarios were run and evaluated

Compressor K-101 Trip with Blow down (300 MMSCFD, 10266 rpm)

Compressor K-101 Trip without Blow down (300 MMSCFD, 10266

rpm)

Cascade Control Output (OP) Back Initialization Evaluation

Oct 2, 2014 13


SCENARIO1: RESULT

Oct 2, 2014 14


SCENARIO 2: RESULT

Oct 2, 2014 15


ANALYSIS OF COASTDOWN SCENARIOS (1 OF 2)

RPM Plant Data DYNSIM - No Blow down DYNSIM - with Blow

down

Time (s) Time (s) % Abs. Error Time (s) % Abs. Error

9000 3.3 3 9.09 3 9.09

8000 5.6 5 10.71 5 10.71

7000 6.8 7 2.94 7 2.94

6000 8.1 9 11.11 9 11.11

5000 9.4 10.9 15.96 11.1 18.09

Comparison of Predicted Coastdown rates and actual plant

data

Oct 2, 2014 16


ANALYSIS OF COASTDOWN SCENARIOS( 2 OF 2)

DYNSIM prediction of initial Coastdown prediction is close to

observed plant data

The initial coastdown rate is critical in design for surge

mitigation Oct 2, 2014 17


SCENARIO 3: RESULT & ANALYSIS (1 OF 2)

Correct backtracking of selected output to the 2 non-selected

controllers Oct 2, 2014 18


SCENARIO 3: RESULT & ANALYSIS (2 OF 2)

Correct SP tracking PV behaviour for FC101 during switch from

Cascade to Local Auto and back

Oct 2, 2014 19


CONCLUSIONS (1 OF 3)

Initial Compressor Coastdown prediction in DYNSIM is close to

actual plant data (about 10% difference). Much higher differences

were observed in some studies in the past.

Coastdown rate prediction from 50% of operating speed to zero

speed is slightly slower than plant data.

Time predicted to reach zero speed is within 10-12% of plant

data.

Oct 2, 2014 20



Better match of Coastdown rate at lower speeds could be

achieved if performance curves at lower speeds were available. In

their absence, the model uses Fan Laws for extrapolation. This is

a less accurate method.

However as seen before, it is the initial Coastdown rate that is

important in sizing of anti-surge valves and for decisions on

hot/cold gas bypass.

Oct 2, 2014 21



For Cascade Control via a selector, the DYNSIM controllers

correctly backtracked the selected output for reference to the 2

non-selected controllers. Correct SP Tracking PV behaviour for

the Compressor Flow controller FC101 was also confirmed.

DYNSIM Shaft unit operation makes it easier to model

Compressor Inertia and Speed behaviour. It also helps in better

modelling and representation of drivers like Motors, Gas Turbines

and Steam Turbines.

Oct 2, 2014 22


OTHER OBSERVATIONS

Anti-Reset Windup as suggested in the DYNSIM FAQ manual

results in non-selected controllers having the same output as

selected controller.

Actually non-selected controller outputs should be higher(for Low-

Select) or lower(for High-Select) than the selected output.

Implementation was modified to achieve Correct Anti-Reset

Windup behaviour.

Oct 2, 2014 23


Q & A

Oct 2, 2014 24


REFERENCES

Botros, K.K. and Ganesan, S.T., 2008,“Dynamic Instabilities in

Industrial Compression systems with Centrifugal Compressors,”

Proceedings of the Thirty-Seventh turbo machinery Symposium,

Turbo machinery laboratory, Texas A & M University, College

Station, Texas, pp. 119-132

Moore, J.J., Garcia-Hernandez, A., Blieske, M., Kurz, R., Brun, K.,

2009’, Transient Surge Measurements of a

Centrifugal Compressor Station during Emergency Shutdowns,

38th Turbo machinery Symposium, Houston, Texas.

Oct 2, 2014 25

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