Session: 11-04-03 Well Cementing Theory & Practice

Paper Number: 122903

122903 - Long Horizontal Slim-Hole Cementing Technologies for Cost-Effective Development in a Middle East Ultra Low Permeability Reservoir 

The S ultra-low permeability reservoir accounts for more than 25% geological reserves of a giant Middle East Oilfield. 70 horizontal wells with more than 5000m MD have been planned and the infinite stage cementing fracturing technique is proposed in a 1000m horizontal section for S reservoir cost-effective development. The liner cementing quality in long horizontal sections is the key to the success of good zonal isolation and premises of effective hydraulic fracture operation. 

To improve the efficiency and performance of 4 1/2'' liner cementing, a comprehensive series of numerical simulations of cementing process and experimental research of core additives have been carried out to overcome slim-hole cementing challenges such as poor centralization, insufficient mud removal or displacement, and low cement bond quality. The cementing operation procedure was optimized including centralizer selection, cementing liquid column design, Rheological property design, and cementing operation program.  The integrity mechanical model of cement sheath was established to design the high efficiency washing space fluid and flexible cement slurry based on experimental results.

By simulating the mud removal and cement slurry placement process, an integral elastic centralizer and centralization program was recommended, sequence of cementing fluid with appropriate density and volume of spacer was determined. Lead slurry and tail slurry rheology property was determined in view of the friction pressure hierarchy concept, and the variable pumping procedure has been optimized according to the change of ECD at the bottom of the well to achieve better effective mud displacement. Meantime, the mechanical properties of the cement sheath were demonstrated by integrity analysis under the condition of multistage fracturing in horizontal section and concluded that the cement sheath shall meet the requirements of Elastic modulus＜6.5GPa, Poisson’s ratio＞0.18, Compressive strength ＞24MPa, Tensile strength ＜2MPa. In terms of cementing fluid, key additives have been introduced, a new oil displacement washing space fluid was formed by experimental screening of the high-efficiency flushing agent and suspension stabilizer. A new toughening agent was also developed. The mechanical property of cement sheath meets requirements and the new toughened slurry is characterized with good sedimentation stability, zero free water, low fluid loss, and good rheology.

Liner cementing key techniques have been developed to achieve effective zonal isolation and good cement bond quality in challenging long horizontal slim-hole cementing. The efficiency and performance of the liner cementing operation increased significantly and are expected to deliver a successfully optimized liner cementing operation for all future horizontal wells.

Presenting Author: Zhen Nie Research Institute of Petroleum Exploration & Development, CNPC

Presenting Author Biography: Zhen Nie is a technical expert in RIPED, has a Doctorate degree from China University of Geosciences(Beijing), her main research direction is drilling and completion engineering. She has published over 10 particles in international journals. She has been the director for 10 major overseas projects and the main researcher in drilling economic evaluation projects. She is also a Master's tutor at Southwest Petroleum University.

Authors:

Zhen Nie Research Institute of Petroleum Exploration & Development, CNPC
Shuzhe Shi The Research Institute of Petroleum Exploration and Development, CNPC