Chemical and physical effects of interaction between oilfield chemicals and formation rocks and integration with sand failure prediction models.

Wuyep, Elizabeth Olive

Abstract

Sand failure may result in the production of formation sand at the same time the formation fluids are being produced. Sand failure occurs when the formation stress exceeds the strength of the formation, which is derived mainly from the natural material that cements the sand grain and cohesive forces. The sand failure and production is a serious challenge that, if not properly handled, can have a drastic effect on oil and gas production rate, cause downhole and subsea equipment damage, and also increase the risk of catastrophic failure. Several models exist for the prediction of sand failure in oil and gas wells, but none of these models account for the failure effects of oilfield chemicals on the reservoir rock, which is exposed to significant amounts of these chemicals. Oilfield chemicals have many applications in the oil and gas industry, and have been used extensively as inhibitor, surfactant, biocide, stabilizer, depressant, retarder, scavenger, defoamer, demulsifier, stimulant, and so on. However, the weakening effect that the chemical/formation interaction may have on the grain fabrics has not yet been given due attention as part of the industry's current approach to geomechanical evaluation of reservoir rock for sand failure and production forecast. This thesis investigates the failure effects of some oilfield chemicals (corrosion inhibitor, scale inhibitor and biocide) on the geomechanical strength of reservoir rocks, the mechanisms of interaction and the mechanism of failure. The research used a combination of rock mechanical testing, grain size distribution analysis, analytical techniques and numerical modelling to establish and define the geomechanical and mechanical failure effects of these chemicals and the mechanisms of failure. The failure effects of the oilfield chemicals on sandstone and carbonates may be integrated within any suitable and relevant existing sand failure prediction models. Results clearly show that a dissolution/precipitation reaction took place, weakening the reservoir grain fabrics and reducing the geomechanical strength, which in turn causes sand failure/production. This work has established that volume fraction and porosity change are functions of dissolution and precipitation reactions, and that the dissolution/precipitation reaction is a function of the type of minerals in the rock.

Citation

WUYEP, E.O. 2018. Chemical and physical effects of interaction between oilfield chemicals and formation rocks and integration with sand failure prediction models. Robert Gordon University [online], PhD thesis. Available from: https://openair.rgu.ac.uk

• Thesis Type: Thesis
• Deposit Date: Aug 13, 2019
• Publicly Available Date: Aug 13, 2019
• Keywords: Petroleum engineering; Sand failure; Oilfield chemicals; Grain fabrics; Oil reservoir engineering
• Public URL: https://rgu-repository.worktribe.com/output/348722
• Award Date: Oct 31, 2018