Dispersion and migration of clay fines have been recognized as a source of permeability impairment and production decline in many reservoir formations. This paper discusses the results of laboratory experiments which indicate that the frequently observed permeability loss from fines movement appears to be a function of fluid dynamics in porous media. The results of the study confirm previous findings that fines movement is rate sensitive. Further, it is shown that for every reservoir rock and its gross properties, there appears to be a threshold or critical hydraulic flow rate beyond which particle movement becomes a pore-plugging problem. The onset of fines movements probably occurs before the critical rate and pore-plugging starts after the attainment of the critical rate. A careful determination of the said critical volumetric rate for each reservoir member can be used to program production operations which can be free of serious fines movement problem and productivity decline. Field tests are currently being implemented to evaluate the validity of this laboratory procedure.
References and illustrations at end of paper.
Reservoir rocks contain varying amounts of very small particles of loose solid materials such as quartz grains, feldspars and migratable clay minerals (authigenic kaolinite, dickite, illite). These particles which are commonly located on the interior surfaces of porous matrix are called "formation fines". Dispersion and migration of these particles have been recognized as a source of permeability impairment and production decline in many reservoir formations (1–10). The frequently observed permeability decline appears to be a function of fluid dynamics in porous media. The fluid velocity, in turn, is highly dependent upon gross properties of the reservoir rock, including wettability, pore geometry, particle morphology and interstitial fluids and their ionic environments. Prevention or control of permeability impairment induced by mechanical-hydraulic flow forces has not been seriously addressed by the industry, and hence, the necessity for this paper. The case for kaolinite and illite fines movement occasioned by high liquid velocities is examined in this study.
Large field stimulation data (11–15) support the claim that millions of dollars are spent annually on "clay stabilizers" that may not offer effective control of certain fines movement problems.
This paper presents the results of clay stabilization experiments which show the ineffectiveness of some chemical stabilization methodologies for kaolinite, illite and quartz fines.
This paper discusses an effective method of fines movement control based on the principles of flow dynamics and proper production engineering procedures. The conclusions of this study are based on certain theoretical deductions and analysis of laboratory experimental core flow tests. These results are easily scaled to realistic field rates and serve as a strong basis for completion designs.
The results of the study confirm the findings of previous researchers that fines movement and associated pore plugging are rate sensitive. For every reservoir rock, there is a threshold (critical) volumetric flow rate beyond which particle movement becomes a pore-plugging problem. This paper discusses how this rate can be established as well as how sustained production can be achieved by this simple fluid dynamics control.
