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SLB Software Engineer Interview Guide

SLB Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

At SLB (formerly Schlumberger), software engineering is not just about writing code; it is about powering the global energy transition and optimizing complex physical operations through digital technology. As a Software Engineer, you will build and scale high-performance applications, cloud-native platforms, and intelligent edge systems that directly interface with massive physical machinery, IoT drilling devices, and real-time subsurface data pipelines. The software you develop at SLB has a direct, real-world impact. Whether you are working on the DELFI cognitive exploration and production environment, developing real-time data ingestion pipelines for horizontal drilling operations, or building advanced physical simulation tools, your code will help optimize resource extraction and reduce carbon footprints.

This guide is scoped to a Software Engineer candidate at SLB.

Focus areas

  • DSA (Data Structures & Algorithms)
  • Java
  • Object-Oriented Programming (OOP) concepts

The SLB interview process

SLB candidates report 7 rounds over 4-6 weeks. The stages below are what candidates describe, not a published process.

Online Application

Begin the process by submitting an online application or participating in campus recruitment.

What to demonstrate

  • Begin the process by submitting an online application or participating in campus recruitment
  • Depth in DSA (Data Structures & Algorithms)

How to prepare

  • Answer aloud and timed: Write an efficient algorithm to find all possible palindromic substrings within a given string.
  • Answer aloud and timed: Implement a function to convert a Roman numeral string to its corresponding decimal integer.

Online Assessment

Complete an automated assessment evaluating cognitive abilities, logic, mathematics, physics, and programming skills.

What to demonstrate

  • Complete an automated assessment evaluating cognitive abilities, logic, mathematics, physics, and programming skills
  • Depth in DSA (Data Structures & Algorithms)

How to prepare

  • Answer aloud and timed: Given a directed graph representing a network of sensor nodes on a drilling rig, write a program using Depth-First Search (DFS) or Breadth-First Search (BFS) to detect cycles or find the shortest path.
  • Answer aloud and timed: Write a program to check if two strings are anagrams of each other.

Group Discussions

Participate in group discussions and collaborative exercises to assess communication and leadership potential.

What to demonstrate

  • Participate in group discussions and collaborative exercises to assess communication and leadership potential
  • Depth in DSA (Data Structures & Algorithms)

How to prepare

  • Answer aloud and timed: Implement an algorithm to remove all vowels from a string in-place or with minimal space complexity.
  • Answer aloud and timed: How would you design a REST API to stream real-time sensor data from an offshore rig to a centralized cloud database?

Live Coding Screen

Engage in a live coding session through third-party platforms to demonstrate technical skills.

What to demonstrate

  • Engage in a live coding session through third-party platforms to demonstrate technical skills
  • Depth in DSA (Data Structures & Algorithms)

How to prepare

  • Answer aloud and timed: Explain the core concepts of Object-Oriented Programming (OOP) and how you would design a system of classes to represent different types of drilling tools.
  • Answer aloud and timed: What are the differences between relational databases (SQL) and NoSQL databases, and which would you choose for storing high-frequency time-series sensor data?

Technical Interviews

Attend deep-dive virtual or onsite interviews with engineering managers to discuss technical expertise.

What to demonstrate

  • Attend deep-dive virtual or onsite interviews with engineering managers to discuss technical expertise
  • Depth in DSA (Data Structures & Algorithms)

How to prepare

  • Answer aloud and timed: Explain the role of Cloud Computing in modern software architectures. How would you deploy and scale microservices using containerization?
  • Answer aloud and timed: How do network protocols (such as TCP/IP vs. UDP) impact real-time data transmission in remote, low-bandwidth environments?

Project Presentation

Present past projects to a technical panel to showcase your experience and skills.

What to demonstrate

  • Present past projects to a technical panel to showcase your experience and skills
  • Depth in DSA (Data Structures & Algorithms)

How to prepare

  • Answer aloud and timed: Why do you want to work at SLB rather than a traditional tech-only company?
  • Answer aloud and timed: Tell me about a time you had to work with a difficult teammate. How did you resolve the conflict and ensure the project succeeded?

Behavioral Rounds

Participate in behavioral interviews focusing on safety, inclusion, and cultural fit within the company.

What to demonstrate

  • Participate in behavioral interviews focusing on safety, inclusion, and cultural fit within the company
  • Depth in DSA (Data Structures & Algorithms)

How to prepare

  • Prepare three examples from your own work, each with a decision you made and an outcome you can quantify.
  • Re-read the description of the behavioral rounds above and write down what you would ask to confirm before it.

Where candidates lose points

Master your resume projects

SLB engineers will grill you extensively on your past projects. You must be able to explain the "why" behind every technology choice, architecture decision, and protocol you used. Be ready to explain how you deployed your applications.

Project a strong, collaborative personality

In group assessments, show that you are an active listener and an encouraging team player. Avoid being overly aggressive, but do not fade into the background. Take on structured roles like timekeeper or coordinator if appropriate.

Prepare your technical presentation thoroughly

If you are asked to present a past project, choose a topic you understand deeply. Do not pick an overly complex topic just to impress the panel if you cannot defend the underlying math, physics, or architectural trade-offs during Q&A.

Understand the energy sector

Show that you have researched SLB's transition toward digital energy services and sustainability. Being knowledgeable about how software optimizes physical energy operations will immediately set you apart from candidates who only apply to traditional tech companies.

Questions & practice

Write an efficient algorithm to find all possible palindromic substrings within a given string.

Medium · Coding & Algorithmic Problem Solving

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Implement a function to convert a Roman numeral string to its corresponding decimal integer.

Medium · Coding & Algorithmic Problem Solving

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Given a directed graph representing a network of sensor nodes on a drilling rig, write a program using Depth-F

Medium · Coding & Algorithmic Problem Solving

Given a directed graph representing a network of sensor nodes on a drilling rig, write a program using Depth-First Search (DFS) or Breadth-First Search (BFS) to detect cycles or find the shortest path.

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Write a program to check if two strings are anagrams of each other.

Medium · Coding & Algorithmic Problem Solving

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Implement an algorithm to remove all vowels from a string in-place or with minimal space complexity.

Medium · Coding & Algorithmic Problem Solving

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

What are the differences between relational databases (SQL) and NoSQL databases, and which would you choose fo

Medium · System Design & Core CS Fundamentals

What are the differences between relational databases (SQL) and NoSQL databases, and which would you choose for storing high-frequency time-series sensor data?

Approach

  1. Name the grain you start from and join outward from it.
  2. Check whether any join is one-to-many before aggregating, or the sums inflate.
  3. Say which index the query would use, and what makes it unusable.
  4. Handle the rows that do not match: that is usually the actual question.

Follow-up

  • How does the query change if that join becomes one-to-many?
  • What happens to this when the table is ten times larger?

Denormalise tenant onto revisions and backfill it live

Hard · denormalisation · online migration · backfill

resource_revision (revision_id, resource_id, version, actor_user_id, change_kind, patch, request_id, created_at) has 400M rows and no tenant column; tenant_id lives only on resource. Two reads need it: a tenant-scoped audit feed ordered by created_at DESC, and an offboarding purge. Both join back to resource today. Justify adding tenant_id to resource_revision against those two reads, name the anomaly the copy introduces and the constraint that prevents it, then give the ordered migration for a live table taking 1.2k writes/second — the lock each step takes, how the backfill is batched, and where each step stops being reversible. PostgreSQL 16.

Approach

  1. Justify from the access path rather than from taste. Without the column, the audit feed either scans resource_revision by created_at and discards other tenants' rows, or resolves the tenant's resource_ids first and probes with them — both proportional to the tenant's whole history rather than to one page. With (tenant_id, created_at DESC, revision_id DESC) it is a seek that stops at 50 rows, and the purge becomes a ranged delete instead of a join.
  2. Name the cost exactly: a second copy of a fact can disagree with the first. Make the disagreement unwritable rather than documented — add UNIQUE (resource_id, tenant_id) on resource so it can serve as a foreign-key target, then FOREIGN KEY (resource_id, tenant_id) REFERENCES resource (resource_id, tenant_id) on the revision table. A revision can then only ever carry its parent's tenant.
  3. Step one, expand: ALTER TABLE resource_revision ADD COLUMN tenant_id BIGINT NULL, with no default, so it is a catalogue change and no rewrite. It still needs ACCESS EXCLUSIVE for an instant, and that instant queues behind the longest open transaction on the table while every later query queues behind it — set lock_timeout to 2s and retry rather than wait.
  4. Step two, dual-write: deploy the writer that populates tenant_id on every new revision while reads still use the join. Reversible by redeploying the previous build, because nothing reads the column yet.

Follow-up

  • The backfill is half finished and a rollback is required. What state is the table in, and what does the previous build do with a half-populated column?
  • How do you verify the backfill actually finished, given rows are still being inserted while it runs?

How would you design a REST API to stream real-time sensor data from an offshore rig to a centralized cloud da

Medium · System Design & Core CS Fundamentals

How would you design a REST API to stream real-time sensor data from an offshore rig to a centralized cloud database?

Approach

  1. Say who the caller is and what they do when the call fails halfway.
  2. Define the identity of a request so a retry cannot double-apply it.
  3. Separate accepted, pending, failed and confirmed; they are different facts.
  4. Design the error taxonomy before the success shape; callers branch on it.

Follow-up

  • What happens if the caller retries after a timeout?
  • How does a client discover it is on an old version of this contract?

Explain the core concepts of Object-Oriented Programming (OOP) and how you would design a system of classes to

Medium · System Design & Core CS Fundamentals

Explain the core concepts of Object-Oriented Programming (OOP) and how you would design a system of classes to represent different types of drilling tools.

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Explain the role of Cloud Computing in modern software architectures. How would you deploy and scale microserv

Medium · System Design & Core CS Fundamentals

Explain the role of Cloud Computing in modern software architectures. How would you deploy and scale microservices using containerization?

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

How do network protocols (such as TCP/IP vs. UDP) impact real-time data transmission in remote, low-bandwidth

Medium · System Design & Core CS Fundamentals

How do network protocols (such as TCP/IP vs. UDP) impact real-time data transmission in remote, low-bandwidth environments?

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

If you had to build a physical structure (like a tower) using limited materials (skewers, paper, adhesives) wi

Medium · Presentations & Case Studies

If you had to build a physical structure (like a tower) using limited materials (skewers, paper, adhesives) with a team under a tight deadline, how would you organize the tasks?

Approach

  1. Clarify what is being asked and what a complete answer contains.
  2. State your assumptions explicitly before working the problem.
  3. Say what you would check first and why it is the highest-information step.
  4. Work from the requirement backwards to the design.

Follow-up

  • What assumption would you test first?
  • How would you know your answer was wrong?

Discuss the pros and cons of online marketing vs. traditional marketing, or debate whether artificial intellig

Medium · Presentations & Case Studies

Discuss the pros and cons of online marketing vs. traditional marketing, or debate whether artificial intelligence will completely replace human intelligence.

Approach

  1. Clarify what is being asked and what a complete answer contains.
  2. State your assumptions explicitly before working the problem.
  3. Say what you would check first and why it is the highest-information step.
  4. Work from the requirement backwards to the design.

Follow-up

  • What assumption would you test first?
  • How would you know your answer was wrong?

Present a 10-minute overview of a complex technical project you completed. What were the trade-offs you made,

Medium · Presentations & Case Studies

Present a 10-minute overview of a complex technical project you completed. What were the trade-offs you made, and how did you debug the hardest issues?

Approach

  1. Establish what changed and when, before forming any theory.
  2. Pick a bisection that eliminates candidates whichever way it turns out.
  3. Check the instrumentation before believing the symptom.
  4. Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

  • What would you look at first, and what would it rule out?
  • How would you tell a cause from a coincidence here?

Suggested practice checklist

Built from the rounds and topics SLB candidates report.

Day 1 — Map the SLB loop

  • Write out the reported sequence: Online Application, Online Assessment, Group Discussions, Live Coding Screen, Technical Interviews, Project Presentation.
  • For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 7 reported rounds, with the weakest marked.

Day 2 — Work DSA (Data Structures & Algorithms)

  • Spend the session on DSA (Data Structures & Algorithms), which SLB candidates report being tested on.
  • Write one worked example in DSA (Data Structures & Algorithms) and time yourself on it.

Deliverable: One timed worked example in DSA (Data Structures & Algorithms).

Day 3 — Work Java

  • Spend the session on Java, which SLB candidates report being tested on.
  • Write one worked example in Java and time yourself on it.

Deliverable: One timed worked example in Java.

Day 4 — Work Object-Oriented Programming (OOP) concepts

  • Spend the session on Object-Oriented Programming (OOP) concepts, which SLB candidates report being tested on.
  • Write one worked example in Object-Oriented Programming (OOP) concepts and time yourself on it.

Deliverable: One timed worked example in Object-Oriented Programming (OOP) concepts.

Day 5 — Answer out loud: Coding & Algorithmic Problem Solving

  • Answer aloud, timed: Write an efficient algorithm to find all possible palindromic substrings within a given string.
  • Answer aloud, timed: Implement a function to convert a Roman numeral string to its corresponding decimal integer.

Deliverable: Spoken answers to 2 reported Coding & Algorithmic Problem Solving question(s), under time.

Day 6 — Answer out loud: System Design & Core CS Fundamentals

  • Answer aloud, timed: How would you design a REST API to stream real-time sensor data from an offshore rig to a centralized cloud database?
  • Answer aloud, timed: Explain the core concepts of Object-Oriented Programming (OOP) and how you would design a system of classes to represent different types of drilling tools.

Deliverable: Spoken answers to 2 reported System Design & Core CS Fundamentals question(s), under time.

Day 7 — Answer out loud: Behavioral & Cultural Fit

  • Answer aloud, timed: Why do you want to work at SLB rather than a traditional tech-only company?
  • Answer aloud, timed: Tell me about a time you had to work with a difficult teammate. How did you resolve the conflict and ensure the project succeeded?

Deliverable: Spoken answers to 2 reported Behavioral & Cultural Fit question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Why do you want to work at SLB rather than a traditional tech-only company?

Medium · Behavioral & Cultural Fit

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

Tell me about a time you had to work with a difficult teammate. How did you resolve the conflict and ensure th

Medium · Behavioral & Cultural Fit

Tell me about a time you had to work with a difficult teammate. How did you resolve the conflict and ensure the project succeeded?

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

Are you open to working in the field or visiting offshore rigs to understand how software is deployed in deman

Medium · Behavioral & Cultural Fit

Are you open to working in the field or visiting offshore rigs to understand how software is deployed in demanding environments?

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

Describe a situation where you had to implement or advocate for safety protocols in your past work or academic

Medium · Behavioral & Cultural Fit

Describe a situation where you had to implement or advocate for safety protocols in your past work or academic experience.

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

Where do you see yourself in five years, and how does your career aspiration align with the energy sector's di

Medium · Behavioral & Cultural Fit

Where do you see yourself in five years, and how does your career aspiration align with the energy sector's digital transformation?

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?