Abstract

The objective of this paper is to present a process for improving the planning of gas field development. We discuss how seismic amplitudes and dynamic characterization can be combined to help optimize gas field development. The main concepts, methodologies, and tools, as results obtained are shown for an actual Mexican gas field. A series of amplitude seismic maps were constructed by using 3D seiesmic interpretation. These maprs were the essential part for detecting significant volumes of gas in place. Afterwards, calibrations of these maps with production data used in reserve evaluation studies, resulted in a low risk development strategy for the field. The example gas field is comprised of three producing sandstones at different depths (E, G, and M), and has 20 producing wells. Hydraulic communication and the drainage areas for each reservoir, in both E and M sandstones, were evaluated by using a combination of the amplitude in the seismic anomalies and production data analysis. A good agreement between the seismic amplitude and dynamic characterization of the pressure and production data was obtained, which improved the evaluation of the reservoir quality and the estimation of drainage area, original gas in place, and proved reserves. In E and M sandstones, four and three independent reservoirs have been detected, respectively. The E sandstone has an estimated value of 62 Bscf of originalgas in place and the M sandstone has an estimated value of 110 Bscf of original gas in place. By using the reservoir dynamic model in combination with information of logs, cores, and production data, the economic optimum strategy for the field development was designed, that included the drilling of wells in areas with the best seismic amplitude.

Introduction

The gas field is located in the central area of the Veracruz basin at the southeast of the Port of Veracruz in Mexico. The field was discovered in 1921 with the exploratory well 1, which was perforated by a foreign company.

The field is formed by many lenticular sandstones with gas and abnormal pressures.

The first producer well (well-3) was completed in 1962 on the sandstones from the tertiary. In the field, it has been perforated a total of twenty five wells including well-1. Fourteen wells resulted being gas producers (3, 4, 5, 6, 201, 402, 403, 404, 405, 406, 412, 415, 420, and 436 wells), nine wells resulted being invaded with salt water (10, 12, 13, 15, 101, 407, 414, 428, and Ma-1 wells) and one well resultedplugged up by a mechanic accident (well-102).

In 1999 several works of 3D seismic were performed covering an area of 240 km2 (or 59,305-acre). The interpretation of 3D seismic allowed the construction of diverse amplitude seismic maps. These maps were essential for detecting significant volumes of gas with relation to high amplitude seismic areas, while establishing geological models and delimiting stratigraphic features.

The amplitude seismic maps were calibrated with reservoir and fluid properties as well as production data obtained throughproductive wells from different sandstones, allowed the decrease of economical risk in the development of the gas field and the generation of new exploration opportunities.

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