As the critical parameter of hydraulic fracture evaluation, fracture density is significant for fracturing model optimization and production prediction. To compensate for the low response sensitivity of fracture density and the saturation of fracture evaluation in nonradioactive technology (NRT), we have developed a method based on modifying the neutron self-shielding effect to quantitatively calculate fracture density. The gamma counts of elements with content that did not change before and after fracturing are used to calculate the self-shielding correction factor. We establish the mathematical relationship between the corrected gamma counts of boron and fracture density to achieve a quantitative calculation of fracture density. Compared to NRT, the new method uses measured energy spectral information to eliminate the effect of neutron self-shielding on fracture density and improve calculation accuracy. Meanwhile, the scope or range of accurate fracture density estimation extends from the original 4% to more than 10%. Moreover, we further examine fracture response under different formations and borehole conditions using the Monte Carlo N-particle transport code. The salinity of formation water and borehole water has the most significant impact on fracture density calculation, shale content and porosity, lithology, and fluid type of formation; in contrast, borehole parameters are the least significant. Finally, in this paper, we illustrate the feasibility of the method through a continuous-depth numerical calculation.

Hydrogen gas is a promising clean-energy vector that can alleviate the current imbalance between energy supply and demand, diversify the energy portfolio, and underpin the sustainable development of oil and gas resources. This study pinpoints the factors that govern hydrogen quantification by pulsed-neutron logging. Monte Carlo simulations were performed to map the spatial distribution of capture γ-rays in formations saturated with either water or hydrogen and to systematically assess the effects of pore-fluid composition, hydrogen density, gas saturation, lithology, and borehole-fluid type. The results show that the counts of capture γ-rays are litter in hydrogen-bearing formations. For low-to moderate-porosity rocks, the dynamic response window for hydrogen-saturated pores is approximately 10% wider than that for methane-saturated pores. Increasing hydrogen density or decreasing gas saturation raises the capture-γ ratio while narrowing the dynamic range. Changes in borehole fluid substantially affect the capture-γ ratio yet have only a minor impact on the dynamic range. Lithology imposes an additional control: serpentinite, enriched in structural water, generates markedly higher capture-γ ratios that may complicate the quantitative evaluation of hydrogen.