Effect of Clay Minerals in Oil and Gas Formation Damage Problems and Production Decline: A Case Study, Gulf of Suez, Egypt.

Abstract

Formation damage can be observed from the production decline and injection rates, the diagnosis of formation damage required integrated data from the geological and engineering side,clay minerals has high impact in the formation damage studies. In this paper, two studied wells in the gulf of suez offshore was investigated to define the root causes of formation damage encountered problems, a detailed study about the studied reservoirs mineralogy and cementation, the scanning electron microscope used for studying the configuration, texture, and fabric of minerals, especially clays, in addition X-ray diffraction analysis used to detect the amount and types of clays in the studied reservoirs, revising of the used fluids and interaction between fluids and minerals investigated also. In general, the XRD results for the well A show high amounts of kaolinite reached up to 17% accompanied with the high quartz percentage of the whole samples, other clays are present also as illite with percentage ranged from 3 to 5%, chlorite also present from traces to 1% percent, while in well B Clays are present also as illite with percentage ranged from 4.4 to 8.2, Scanning electron microscopy analysis shows the presence of kaolinite, illite and chlorite in the studied wells. The study revealed that, the formation damage in the well A may results from deflocculatabl kaolinite clay by non-equilibrium water-based fluids with the potential to severely reduce near wellbore permeability, or clay particle dispersion and pore plugging by movement with production, where the movement of fines affects on the production performance of a well, especially in the sandstone formation reservoirs. Salinity chock may be responsible for the clays dispersion. the formation damage in the well B may results from the used stimulation fluid, where Hcl react with illite and break it to fines and this will block the pore throats and cause a severe permeability reduction in the studied well. In general, it's recommended a Core flooding test for the best stimulation for more understanding of the problem. Otherwise, the following mitigations should be considered in these formations; 1. Carefully control the concentration, size and type of solids in the completion or drilling mud if any plan for next wells drilling., 2. Minimize fluid invasion into the formation by controlling the overbalance., 3. Long time of completion fluid in the borehole is not recommended. Key words: core flooding, acid stimulation, xrd.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018