Laboratory Studies of Chemicals for Sand Consolidation (Scon) in the Niger Delta Fields

Abstract

ABSTRACT Sanding during oil production causes severe operational problems in the oil and gas industry. Several techniques have been used for sand production control in sandstone reservoirs. Consolidating materials, such as, crude oil coke and nickel plating have been used in the past by researchers. At present, the chemical binders, such as; phenol resin, phenol-formaldehyde, epoxy, and furan or phenol-furfural provides cementation. This work is centered on the laboratory studies of selected sand consolidating resins that would be suitable for application in the Niger Delta (ND) oil fields. Considering the available resins for consolidation process, six types of chemical resins namely; Epoxy (A&B), Novalak Phenol-Formaldehyde, Furan Phenol Acrylic, Furan and Phenol resins were selected for studies. Three other locally made resins: Rubber Latex, Evo Stik and Polystyrene gum were reviewed alongside for comparison and test for their applicability. Different core samples were made by mixing these resins and their hardening agents with sand sample obtained from a sand producing oil field in the Western Niger Delta. The core samples made were subjected to laboratory qualitative and quantitative analysis in order to obtain individual permeability and porosity under different overburden pressures from 500psi through 3500psi. Results from experimental data show that Epoxy A&B resins ranked best followed by Furan resin and then, the local resins. This was adjudged based on minimal variation in the permeability and porosity of the core samples retained in acceptable values after curing and by analytical result from measurements at various overburden pressures. INTRODUCTION Unconsolidated sandstone reservoirs are most susceptible to sand production, especially those with permeability between 0.5 to 8 Darcies. Sand production in such reservoir may start during first flow or later when reservoir pressure has fallen or water breaks through. Most of the world's hydrocarbons are located in unconsolidated reservoirs(1,2). These rocks are usually relatively young in geologic age, and are unconsolidated because natural processes have not cemented the rock grains together by mineral deposition(3,4,5). Sand production occurs with varying degree of severity, not all of which require action anyway. The rate of sand production may decline with time at constant production conditions and is often associated with cleanup after stimulation. Very soft formations may exhibit sand production at the time of initial discovery; the so called "sloughing?? sands can lead to great difficulties during completion operations when bore-hole collapse can become a major problem. Many others, normally somewhat more consolidated formations begin to show sand production after a considerable period of production - due to reservoir pressure depletion (decrease in minimum in-situ stress), water production, increased fluid velocities etc.