New Alternative to Optimize Cyclic Steam Injection: Field Pilot

Abstract

Abstract This paper presents a technical evaluation of the results obtained in a field pilot to optimize the cyclic steam stimulation (CSS) by evaluating the performance of the indicator of oil steam ratio (OSR). The pilot was based on numerical simulation, where several alternatives or strategies were identified to improve the current technique applied for wells with more of 15 cycles as a method of improved or enhanced recovery in a madure heavy oil field. In a heat transfer process, in this case used by cycle steam injection, once it has maximum use, the next step in most of the termal process is to apply or move to steam flooding tecnic, but the implementation of it requires high investments that currently are not viable. However, it is necessary to provide solutions that contribute to improve the CSS efficiency of the field. The following workflow was developed: (1) research of literarature and field experiences of different alternatives to increase the actual CSS efficiency by only changing the steam injection strategy, without including additional costs related to additives or technologies. (2) selection of the pilot area based on the current petrophysical, production, steam injection conditions and supported by a numerical reservoir simulation model with different sensitivities to define the base case to be developed in the field and (3), the optimal case was implemented in the field during one year. Results are discussed in this paper. An area of the field under study was selected, considering the following conditions: low pressure, high water cut, number of CSS per well greater than 15, inefficient CSS response. (4) alternatives for the optimization of the CSS were identified; these were evaluated by numerical simulation and it was found the optimal development strategy the intermittent injection. With these results, a field pilot was implemented which consisted of 3 injection wells in 3 different patterns, for a period of 12 months of evaluation. During this period, it was possible to reduce the strong decline in oil production presented in the area from 23% to increase to −25% A.e., saving 20,000 mmbtu/ of steam in a year, generating an increase in the OSR of 0.12 BBl / MMBTU; and a decreasing the number of well services jobs from 51 to 27. This result was achieved because areas with oil saturation that had not been previously stimulated in the conventional process of CSS were contacted under this new scheme. The current conditions of the field, low pressure and high saturation of unconnected remaining oil during the conventional cyclic steam injection until now applied in the field, led to propose new cyclic stimulation alternatives such as the one presented in this paper; highlighting the technical results of the pilot developed without additional cost, just changing the injection strategy to optimize the current state of the field.