Super-Large Scale Horizontal Well Position Optimization Method and Infilling Practice in High Water-cut Large Complex Fluvial Reservoir Based On Multidisciplinary Innovative Techniques

Abstract

Tapping the remaining oil with horizontal wells is routinely used in high water-cut oilfields. However, it faces serious challenges in complex fluvial reservoirs with stacked sand body, horizontal interlayers, lateral barrier and complex water flooding conditions. Moreover, the depth uncertainty of the target interval, limited number of offset wells, rapid change of thickness, thin target intervals, and variable fluid contact have also increased the risks of the horizontal well placement. In order to locate the optimal positions of the horizontal wells, get the maximum recovery, reduce the risk of water flooding, minimize the drilling time, we propose a comprehensive well planning and optimization method based on multidisciplinary innovative techniques. New techniques from geology, geophysics, and drilling engineering are assembled to efficiently perform the challenging task. Firstly, an improved interwell 3D correlation technique was proposed to characterize the single sand body. The technique can depict the vertical hierarcy of reservoir. Secondly, we propose a lateral boundary delineation technique based on seismic geometrical attribute. Combined with ant tracking algorithm, we are able to extract the 3D lateral discontinuous surfaces. Based on above technique, we can build detailed architecture model fast and optimize the positions of horizontal wells. Considering the geological uncertainty, the boundary mapping tool is used to optimize the well trajectories in real time to avoid the water flooded zone and shale zone, and to stay in the sweet zone. We applied the integrated workflow in Q oilfield in Bohai Bay basin, East China. 112 horizontal wells are drilled. The drilling results proved that boundary mapping tool can achieve smooth landing of well path and delineate the accurate geometry and thickness variation of sand body which reduces the depth uncertainty of seismic horizon explanation, and keeps the horizontal well trajectories away from oil-water contact. The production results show that 86% horizontal wells have achieved low water-cut and high oil production rate. The total production rate of Q oil field has increased by 2.5 times.

Seismic-driven geocellular modeling of fluvial meander-belt reservoirs using a rule-based method

“…The central point-bar body was modeled for scopes of development planning, and in particular to guide decisions on well configurations. The adoption of horizontal wells is an increasingly common strategy for producing meander-belt reservoirs (Carter et al 1998;Balke & Rosauer 2002;Svanes et al 2004;Wu et al 2008;Harr et al 2011;Pakdeesirote et al 2016;Wang et al 2016). In heterogeneous point-bar deposits, whether such a strategy is viable and preferable over vertical drilling, and what the ideal well orientation and position might be, are likely determined by accretion geometries and the relative distribution of sand and mud, in addition to the presence and spacing of mud plugs (Colombera et al 2017).…”

Geometry and compartmentalization of fluvial meander-belt reservoirs at the bar-form scale: Quantitative insight from outcrop, modern and subsurface analogues

“…In particular, given that perforation of horizontal wells has been suggested and implemented as a way to tackle stratigraphic compartmentalization in meander-belt reservoirs (Schenk 1992;Carter et al 1998;Pranter et al 2007;Wu et al 2008;Harr et al 2011;Pakdeesirote et al 2016;Wang et al 2016), the empirical characterization presented above provides information that is useful for defining the optimal spacing and length of horizontal wells. When dealing with multi-lateral channel bodies, horizontal wells oriented orthogonally to the channel-belt axis (i.e., in the overall cross-stream, or strike, direction) might be suggested, given that point-bar lengths are larger than widths (Figure 2), as this will result in a larger proportion of bars and compartments intersected for a given borehole density.…”