Abstract

Reservoir productivity and profitability can be optimized through careful design of non-damaging drilling and completion programs, Determination of primary and diagenetic reservoir characteristics via petrologic techniques can provide the necessary criteria to design such programs. Petrology is a valuable tool in maximizing performance of both conventional fields and areas subjected to thermal enhanced recovery projects.

Petrologic techniques utilized in reservoir evaluation include thin section petrology, scanning electron microscopy and x-ray diffraction analysis. Useful results can be obtained through examination of either core, sidewall Core or Chip samples. Reservoir quality or fluid sensitivity problems which may be anticipated include:

  1. fines migration

  2. acid sensitivity

  3. fresh water sensitivity

  4. sand production,

  5. fluid incompatibility

  6. mineral transformations (under thermal EDR)

  7. the formation of damaging scales, emulsions Or other precipitates.

Identification of zones which would benefit from carefully designed acid or fracture stimulation programs is another practical application. Semi quantitative analysis of the degree of anticipated damage during completion or improvement during clean-up can be obtained through supplementary tests such as core flooding at reservoir conditions.

Optimum well productivity and maximum resource recovery depends on a thorough understanding of reservoir characteristics. Primary lithology and subsequent diagenetic modifications control the distribution of porosity and permeability and the type of reservoir quality or sensitivity problems which may be encountered. Identification of potential problems prior to well completion, field development and enhanced recovery techniques allows design of non-damaging drilling, completion and stimulation programs. In addition, analysis of damaged zones may allow development of successful clean-up programs.

Introduction

The decline in world oil prices necessitates implementation of relatively inexpensive tools to facilitate resource characterization and development. Optimum well productivity and maximum resource recovery depends on a thorough understanding of reservoir characteristics. Determination of primary and diagenetic reservoir properties via petrology can assist in design of non-damaging drilling and completion programs. resulting in increased reservoir productivity and profitability.

PETROLOGIC TECHNIQUES ANO APPLICATIONS

Petrology provides an inexpensive evaluation tool that can yield useful results through examination of core, sidewall core, or chip samples. Standard petrologic techniques utilized in reservoir evaluation include thin section petrology, scanning electron microscopy and x-ray diffraction analysis. The application of petrology in reservoir evaluation has been documented extensively (1).

Thin section petrology forms the basis of any petrologic study and involves transmitted light microscope examination of thin slices of recovered reservoir material. This information is used in the interpretation of potential reservoir sensitivity or quality problems. Preparation of thin sections involves impregnation of porosity with a coloured epoxy, mounting of the impregnated sample on a glass slide and planning of the sample to a 30 micron thickness. Both conventional and oil sand samples can be prepared for thin section examination. Thin section petrology can provide information on primary lithology, diagenetic modifications and controls on porosity and permeability. Other related techniques include impregnation with a fl

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