Horizontal Well Performance Evaluation and Fluid Entry Mechanisms

Abstract

Abstract In this paper, the use of various measurements is presented for performance evaluation of horizontal wells. The importance of formation evaluation and the challenges of testing in horizontal wells are reviewed. Factors affecting the productivity of horizontal wells are explored. The difficulties in horizontal well productivity estimation due to their long length in the formation compared with vertical wells and inadequacy of measurements during drilling and production are shown. It is also shown that how reservoir heterogeneity affects the reservoir pressure distribution and hence fluid entry profiles and well productivity. Using field examples, we show that the new integrated production logging measurements can be used to assess horizontal well productivity by identifying productive zones, fluid entries, and determining the fluid distribution (oil, gas, and water) in the well- bore. A range of fluid entry mechanisms from over twenty recently logged wells are described and classified. The continuing development of production logging technology for horizontal wells is described. The field examples indicate that horizontal wells have permanent water sumps, regard- less of whether they produce water or not, which leads to reduced oil entry. Performance simulations have shown that for these horizontal wells a 30 to 50 percent productivity (PI) reduction is found when they are compared with their full potential. P. 365