Comprehensive Multiple Fracture Pressure Analysis Tests to Appraise and Develop Unconventional Organic-Rich Carbonaceous Shales in North Kuwait

Abstract

A comprehensive diagnostic data-fracturing campaign (Fracture Pressure Analysis: FPA) was undertaken by the Gas Fields Development Group (GFDG) of North Kuwait in January-March 2013. The campaign involved executing FPAs on the primary zone of interest (Organic-rich Carbonaceous Shale: OCS) as well as underlying and overlying carbonates to establish "fraccability" and in particular the hydraulic frac vertical containment aspect, which are much needed for the successful planning of an appraisal program. This paper summarizes the resuts of those FPA tests and how the acquired data is used to calibrate the wellbore geomechanical model. This initial FPA campaign is the onset of a more comprehensive evaluation program planned for 2013 onwards. FPA sequences were executed on the OCS, underlying and overlying formations with encouraging results. The main concern was whether the OCS would yield hydraulic fracture (fracture initiation) below surface treatment pressure limitation of 13,500 psi (Maximum allowable surface pressure). The fracture initiation was successfully established in all three zones. In addition, multiple "fracture re-opening tests" were performed to evaluate the ranges of the fracture closure stresses during the leak-off. Multiple down-hole memory gauges were utilized to ensure elimination of wellbore effects on treatment pressure. KCl-laden incompressible water-based fluid system enhanced with friction reducer was utilized in all three stages to ensure minimal friction loss and damage. This formation suite has very complex mineralogical attributes as it is a mixture of clastics, carbonates and hydrocarbons, with reservoirs that can be very tight (possibly at micro-Darcy). This campaign will lead to an optimal selection among the vertical completion options (hydro-fracturing design), and will help to successfully plan for horizontal well completions.

Влияние Петрофизических Параметров Рифогенных Карбонатных Коллекторов Нефтяных Месторождений Турнейско-Фаменских Отложений Верхнего Прикамья На Продуктивность Добывающих Скважин

“…Исследования, проведенные в трещинно поро вом типе коллектора, обладающем открытой тре щиноватостью, выделяются особым видом кривой восстановления давления (КВД). Кривые восстано вления и падения давления, в соответствии с мо делью Уоррена-Рута, графически представлены двумя параллельными линиями вместо однойкак в случае порового коллектора [18][19][20][21][22]. Тре щинно поровый пласт в модели Уоррена-Рута представляет собой одинаковые прямоугольные параллелепипеды (моделирование матричных бло ков), которые разделены трещинами.…”

Increasing Production and Reserves in a Mature Field with Hydraulic Fracturing by Combining Fracture Pressure Analysis, Pressure Transient Analysis, and Rate Transient Analysis

“…Most of the injected fluid is believed to be slowly transferred from the dominant fractures into a network of dynamically activated fissures long after the fluid injection stops, and any diffusion into the matrix itself (with permeability ranging from 10 to 100s nanodarcies) would require a well to be shut-in for an unrealistically long period of time to see any recognizable reservoir response. Although it may be possible to have more confidence in the evaluation of in-situ stresses by combining classical FPA with repeated cycles of injection and depressurization (Fidan et al 2014), proper characterization of the reservoir transmissibility and pressure is still hindered by the inerrant complexity of the fracture/fissure interactions and the theoretical time required to reach a transient flow regime in a tight reservoir.…”