The definition of a production strategy is one of the most important tasks in reservoir management, since it will affect the reservoir behavior, which influences future decisions, economical analysis and, consequently, attractiveness of projects. It involves variables like well placement, number and type of wells, operational conditions, reservoir characteristics and economic scenario. The analysis becomes more complex when horizontal wells are considered in production strategy, due to their interaction with reservoir, which demands tools to assist the decision-making process by discarding less attractive alternatives and providing analysis of a reduced number of solutions.
This paper proposes the use of a Quality Map, which is a two dimensional representation of regions with production potential in a reservoir, to guide horizontal wells placement, in order to reduce time-consuming and analysis efforts. The major factors that affect horizontal wells location and productivity will be identified and three methods of Quality Map construction will be presented and compared. Applications of Quality Map will also be discussed.
The main activity in reservoir engineering is the planning of strategies for the development and management of petroleum fields. The determination of well location is one of the most important aspects in production strategy definition, and the optimization procedure related this problem is complex. The analysis becomes harder when horizontal wells are considered, due to its interaction with the reservoir. The process of choosing the best location for horizontal wells demands time-consuming and computational efforts, since its productivity depends on many variables related to reservoir and fluid properties, and well characteristics. Optimum reservoir management is an important theme in petroleum industry. Most of the studies related to reservoir performance optimization focus the well placement.
Aanonsen et al1 proposed a method to optimized well locations under geological uncertainties based on response surfaces and experimental design. Multiple regression and kriging were used to reduce the number of simulation runs.
Optimum horizontal well location with respect to water-oil and gas-oil contacts was proposed by Wagenhofer and Hatzigmatiou2. Their work deals with simultaneous water and gas breakthrough time prediction to define the distance that corresponds to the optimum horizontal well location, which maximizes the prebreakthrough cumulative oil production free of water and gas-cap production. Oil flow rate, oil viscosity, oil formation volume factor, water-oil density difference, perforation interval length, oil water mobility ratio and water column height are the major factors that affect the horizontal well location.
Bittencourt and Horne3 developed a hybrid algorithm based on direct methods such as genetic algorithm, Polytope search and Tabu search to obtain the optimal solution for problems related to reservoir development. Simulator was used as a data generator for the evaluation of the objective function, which involved an analysis of cash flow. G?yag?ler and Horne4 have also used genetic algorithm to reduce computational burden in a well placement optimization problem upon uncertainties.
Cruz et al5 introduced the concept of quality map which was applied to evaluate the well location and scheduling of vertical wells, to compare reservoirs, to classify stochastic realizations and to include uncertainties related to reservoir characteristics.