Acid Stimulation Learnings from an Unconventional Reservoir

Abstract

The California's Monterey formation is thought to hold significant hydrocarbon potential and is looked upon as a long term opportunity for development. Given its unique depositional environment, digenesis and very low permeability the hydrocarbon bearing formations have been referred as unconventional reservoirs. Since early 1900's the San Joaquin Valley's Monterey formation has been targeted and produced by several determined and ambitious operators. Still today, these operating companies are trying to develop an understanding of how to best develop and economically unlock this potential to further exploit the resource. Different stimulation techniques, such as hydraulic fracturing and acid treatments, have been used in an attempt to unlock the resource. It was observed that, while hydraulic fracturing was to some extent effective in several fields, other reservoirs have been found to respond very well to acidizing treatments. The wealth of acid treatment data and corresponding production response from the Monterey formations present a great analysis opportunity to identify best practices and optimize well completions to maximize production. This paper presents a study undertaken to analyze the acid stimulation treatments in one of the structures of the Monterey formation and consists of two parts. The first part covers the descriptive analysis and involves the use of supervised and unsupervised clustering techniques to evaluate the relationship between acid treatments and production data. Its objective is to understand the success of the treatments and to identify acid job best practices. In the second part, using only the available information and cluster knowledge extracted, an attempt was made to develop a predictive tool to forecast the performance of new/infill wells and re-stimulation treatments. The study revealed a relatively good understanding of the factors affecting the production response of individual wells and also the variations observed in the different parts of the field. Shortly after the completion of the study, the operating company executed similar activities to what the study found, unbeknownst to the authors. The positive results achieved were not only a validation of the recommendations but also demonstrated the business value created by such analyses.

Development of Acid Nanocapsules with Tailored Breaking Reservoir Temperature for the Removal of Formation Damage by Fines Migration

“…The concentration of HF was defined according to the literature. Research has established that HF at concentrations between 1.0 and 3.0% w·v –1 guarantees strongly acidic solutions with pH values below 3.0, considering the HF dissociation constants equal to 6.7 × 10 –4 , which improve the dissolving power of acid treatments. ,,, …”