Hydrocarbon development from tight gas sandstone reservoirs is revolutionizing the current oil and gas market. The most effective development strategy for ultralow- to low-permeability reservoirs involves multistage fracturing. A cemented casing or liner completed with the plug-and-perf method allows nearly full control of fracture initiation depth. In uncemented completions equipped with fracturing sleeves and packers, clearly identifying the fracture initiation points is difficult due to lack of visibility behind the completion and long openhole intervals between packers. Also, the number of fractures initiated in each treatment is uncertain. A lateral was completed with access to 3,190 ft of openhole section across five fracturing stages in a high-temperature and high-pressure tight-gas interval. All stages were successfully stimulated, fracture cleanup flowback was conducted, and entry ports were milled out. A high-definition spectral noise log (SNL) was then conducted along with numerical temperature modeling. Additional logging was done with a set of conventional multiphase sensors. A multi-array production log suite was also performed. Finally, the bottom four stages were isolated with a high-temperature isolation plug based on the integrated diagnosis. The SNL helped to analyze the isolation packer integrity behind the liner. The initiation of multiple fractures was observed, with as many as nine fractures seen in a single-stage interval. A correlation was found between the openhole interval length and the number of fractures. A correlation of fracture gradient (FG) and initiation depths was made for the lateral in a strike-slip fault regime. The fractures were initiated at depths with low calculated FG, confirming the conventional understanding and increasing confidence in rock property calculations from openhole log data. SNL and temperature modeling aided quantitative assessment of flowing fractures and stagewise production behind the liner. Multi-array production logging results quantified the flow and flow profile inside the horizontal liner. The production flow assessments from both techniques were in good agreement. The integration of several datasets was conducted in a single run, which provided a comprehensive understanding of well completion and production. High water producing intervals were isolated. Downstream separator setup after the isolation showed a water cut reduction by 95%. The integration of the post-fracturing logs with the openhole logs and fracturing data is unique. The high-resolution SNL provided valuable insight on fracture initiation points and the integrity of completion packers. Fracturing efficiency, compared to the proppant placed, provides treatment optimization for similar completions in the future.

Near-wellbore fracture diversion is a common means of achieving uniform stimulation in long wellbores through heterogeneous reservoirs. A novel sequenced fracturing technique using self-degradable, nondamaging, multimodal particulate pills was deployed for the first time in a clastic rock formation in the Middle East. Application of an advanced design and evaluation workflow to stimulate two perforated intervals in a single continuous pumping operation is presented. Sequenced fracturing with two-step diversion was combined with channel fracturing to increase the chance of successful placement and reduce the inherent risk of screenout. Two proppant ramps were pumped, separated by a diverter pill composed of a multimodal particulate blend and fibers. The size distribution and volume of particles were optimized to create a low-permeability plug in the entry of the primary fracture. The pills were designed so that large particles would intercept the fracture entrance and smaller ones would reduce the permeability of the formed plug, while the fibers would help to maintain the plug integrity both during pumping and once it formed in the near wellbore region. Diversion was confirmed by a pressure increase of 800 psi during the placement of the pill, followed by a new breakdown signature and a treating pressure increase of 500 psi at the same pumping rate. The diversion design was optimized based on the temperature log before fracturing to evaluate the preferential fracture geometry. The evaluation was conducted with a nonradioactive traceable proppant that was pumped in the second proppant ramp to assess the proppant placement using a neutron log. Consequently, a production log was conducted followed by pressure diagnostics. Since the diagnostic results indicated some ambiguity, for a way forward in the field development, the upper interval was refractured and showed high pressures and early treatment termination. The entire flowback timeline was compared, and the productivity index showed no change before and after refracturing. Therefore, multiple pressure diagnostics, post-fracturing flowback enhancement, and the overall intense evaluation verified proppant placement in both perforated intervals using the sequenced fracturing technique. The technique has the potential to save up to 10 days of completion time, which was calculated to yield approximately 40% time and cost savings. This paper presents a complex stimulation treatment analysis that can be utilized to apply the lessons learnt in design and evaluating the success of diversion treatments to aid future treatments. This proven technology enhances efficiency and economics, especially in multistage fracturing, where the efficiency could be enhanced by three- to fivefold.

The main objective of the acoustic logging in 15K openhole multistage fracturing completions (OH MSFs) is to identify the fracture initiation points behind pipe and contributing fractures to gas production. The technique will also help to understand the integrity of the OH packers. A well was identified to be a candidate for assessment through such technique. The selected well was one of the early 15K OH MSF completions in the region that was successfully implemented with the goal of hydrocarbon production at sustained commercial rates from a gas formation. The candidate well was drilled horizontally to achieve maximum contact in a tight gas sandstone formation. Similar wells in the region have seen many challenges of formation breakdown due to high formation stresses. The objective of this work is to use the acoustic data to better characterize fracture properties. The deployment of acoustic log technology can provide information of fractures initiation, contribution for the production and the reliability of the isolation packers between the stages. The candidate well was completed with five stages open-hole fracturing completion. As the well is in an open hole environment, a typical PLT survey provides the contribution of individual port in the cumulative production but provides limited or no information of contributing fractures behind the pipe. The technique of acoustic logging helped to determine the fracture initiation points in different stages. If fractures can be characterized more accurately, then flow paths and flow behaviors in the reservoir can be better delineated. The use of acoustic logging has helped to better understand the factors influencing fracture initiation in tight gas sandstone reservoirs; resulting in a better understanding of fractures density and decisions on future openhole length, number of fracturing stages, packers and frac ports placement.