A Comparative Analysis for Optimal Fracture Design Between the Crest and Flank Wells. Examples from Saih Rawl, Oman Tight Gas Field

Abstract

Saih Rawl gas is located in the South Oman Salt Basin. There are two main formations targeted for gas production; Barik & Miqrat Formations. These formations are tight and exhibit low permeability. In order to enhance gas production, these formations have to be hydraulically stimulated. The main objectives of this paper is to demonstrate the petrophysical properties of the hydraulically fractured zones. Assess gas flow contribution thru the individual zones measured by production logging and comparing with the amount of proppant placed in the formation. In addition, the paper discusses reservoir properties and characteristics obtained from logging, post stimulation operations results and post stimulation gas production. The paper discusses 20 wells; 10 from the crest and 10 from the flank. The two formations Barik and Miqrat cover approximately 17 sub reservoir units. The total overall placement ratio is 95% and 78% for the crest and flank respectively with 156 hydraulic stimulation stages. It was observed that five sub reservoir units proved to be challenging to place the desired proppant. The maximum operating pressure is reached before achieving the desired proppant concentration leading to a screen out; concentrations of 2 – 3 pounds per gallon. Petrophysical evaluation of porosity and permeability cross plots showed a linear relationship in the wells in the crest. While there was no clear relationship was seen in the flank. Radioactive tracers used are to understand if there is any proppant propergation into the higher or lower zones. Not all the five challenging sub reservoir units showed propergation to other units. The wells located in the crest showed a better production rate as compared to the flank. The paper highlights the importance of the using petrophysical evaluation to optimize hydraulic fracturing design for successful operations.