On a sprawling abandoned sugar estate by the coast of Guyana, the scale of the changes sweeping across the country is immediately visible. In just a few years, enormous warehouses and office buildings servicing international oil companies have sprung up amid the shrub land, irrigation canals and fields of wild cane. People are “moving from cutting cane to businessmen,” said Mona Harisha, a local shop owner. “It changed so fast.” Guyana is giving up its past as an agricultural economy and speeding toward its near-term future as an oil-producing giant. And so Ms. Harisha has renovated her general goods shop, redolent of Indian spices, which she runs from a side of her cottage in the Houston neighborhood of Georgetown, the county’s capital. She said oil companies have brought jobs and better roads, and have raised home values — […]