Problem Solving of Flow Assurance due to Viscosities Issue in the Oil Well Flowline of Field-X Using Surface Chemical Injection

Abstract

Several wells in X Field have problems related to high pressure in the flowline due to high viscosities which are related with X-crude pour point properties. Current practice to solve the problem is by chemical stimulation to the wellbore using solvent. The chemical is proposed since it can create oil water emulsion, which hypothetically may have lower viscosity than the crude oil itself.

Historically, opportunity to utilize viscosity reducing chemical agent already identified and laboratory tested in 2017 and 2018 from two company providers. The Operation Laboratory conducted rheology tests at various chemical concentrations to determine whether chemical injection will give better flowability of the crude oil. One of the recommendations from the laboratory test is to conduct a field trial to see the real effectiveness and also compatibility with field operation. Project team decided to implement a different methodology to reduce viscosity through surface chemical injection.

This pilot project started with selection candidates in which congeal wells are mostly located in Area A, B, C, and D in X field. After candidates are fixed, the project team measures the oil properties (viscosity, water cut, pour point, and oil well test) for each well (before chemical injection). Parallel with candidate selection, the project team also executed a procurement process to purchase chemical and injection equipments.

After preparation completes, continuous chemical injection takes place in the surface pipeline. So, the producer well is still ON while the chemical pump keeps injecting solvent chemicals. During continuous chemical injection, the project team measures the oil properties and well tests to see the impact from solvent chemicals. This pilot project took two weeks of continuous injection for each well and after that injection stopped and the project team evaluated the result.

After doing surface chemical injection for 5 wells, it is concluded that chemical X gives a positive impact to oil viscosity that flows in the surface pipeline. Oil viscosity is reduced 30 – 50% after injecting solvent chemicals (4 out of 5 wells). This ultimately will increase oil production. Viscosity reductions happen effectively at 3-5 days after injection starting and higher injection rate from chemicals will result in larger viscosity reduction. Viscosity reduction result also varied by well depending on initial oil production, water cut, congeal severity, and wellhead temperature.