Located in offshore South China, Panyu oil field has entered into mature development phase after a decade of intensive production the water cut of the field had raised to 91%. It was then decided to start targeting less than 5m thin heavy oil reservoirs with density 0.93 - 0.96 g/cm3, 14-17API Gravity and with dynamic viscosity of 275 cP to increase the production and reserve recovery of the overall field. The only way to extract heavy oil from these reservoirs was from drilling horizontal wells.

However, exploiting these targets presents operational challenges with increasing complexity with heterogeneous formation, presence of bottom water and heavy oil property. To overcome, need strategic well planning, the horizontal well needs to be optimally placed within complex target zone, the lateral also needs to be placed as close as possible to the reservoir top to keep it away from the unknown current fluid contact and design a completion to minimize water conning.

This paper features the best practices of making strategic planning and spacing of horizontal wells in the field for efficient draining of the reservoir, drilling of horizontal wells close to top of reservoir to optimize the distance between horizontal section and oil water contact that is very sensitive to well performance and reserve recovery. This includes precise landing with low incident angle and lateral placement within less than 0.5m window below the reservoir top utilizing the directional electromagnetic and wellbore imaging applications for detail reservoir profiles description and current OWC level identification while drilling and further designing a completion in a combination of step screen and stinger to balance the pressure drawdown along the lateral for minimizing the water coning.

Multiple wells' field cases will be discussed in the paper based on 16 horizontal wells completed during the course of the project. Several key outcomes that have been observed during the execution and upon the completion of the well will be highlighted, including:

  • Clear identification of the reservoir geo-bodies and their interfaces including the current fluid contact level

  • Optimum lateral placement in the best position to drain the reservoir

  • Completion design for optimal production

The authors conclude that heavy oil reserve recovery enabled through horizontal wells drilling and completion program. The implementation of the best practices in operation is the key to drain the heavy oil effectively and optimally.

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